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1 //! The renderer-agnostic half of the make-family design system.
2 //!
3 //! <!-- wiki: makeover-layout -->
4 //!
5 //! `makeover` answers *what colour*, and varies by theme. `makeover-geometry`
6 //! answers *how much space*, and varies by density and surface. This crate
7 //! answers *what the thing is*, and varies by nothing.
8 //!
9 //! # The deferral rule
10 //!
11 //! A description names intents and relationships, never values. Say
12 //! [`Fill::Raised`], never `#D9DDF4`. Say `Gap::Peer`, never `6px`. What is
13 //! left once colour and spacing are deferred is **composition**: which edges
14 //! are lit, what inverts on press, what nests in what.
15 //!
16 //! The constraint that shapes all of it: a renderer that can only paint
17 //! rectangles has to be able to express the result. egui has no
18 //! `box-shadow: inset` and one stroke per widget with no per-side control; a
19 //! terminal has box-drawing characters and one cell of resolution, and cannot
20 //! draw a two-tone lit edge at all. A description that assumes per-side edges
21 //! is a CSS description wearing a neutral name. So this crate names the
22 //! *intent* — this region is a well — and each renderer chooses an expression
23 //! it can actually produce, including dropping half of one.
24 //!
25 //! # Scope
26 //!
27 //! Depth came first: the bevel and the surfaces it shapes. That much was
28 //! settled the hard way — the vocabulary here was read off audiofiles'
29 //! `ui::theme` and `ui::widgets`, which are the only implementation written
30 //! by a consumer with no CSS, then checked against both webview apps. All
31 //! three agreed once Balanced Breakfast's fills were corrected.
32 //!
33 //! 0.2.0 adds the rest of the description, each member drawn the same way,
34 //! from what the three apps already hand-write rather than from a taxonomy:
35 //!
36 //! - Components. [`Token`] (badge against chip), [`Notice`] (toast against
37 //! banner), [`RowPart`], [`Heading`], [`Selector`], [`Readiness`], and
38 //! [`Tone`], which is the one intent family they share.
39 //! - Schemas. [`Field`] for forms and [`Column`] for lists and tables.
40 //! - Structure. [`Region`] for the parts of a screen, [`Arrangement`] for how
41 //! a screen is put together.
42 //!
43 //! **Validation** was absent on purpose here, on the grounds that neither app
44 //! had a shared story. That reasoning is retired — see 0.11.0 below, which is
45 //! where the constraints arrived and why the argument did not survive contact
46 //! with what the apps were measured to do.
47 //!
48 //! 0.3.0 closes a gap the first real adoption found, which is what adopting
49 //! against goingson first was for. [`Selector`] described only the *chosen*
50 //! option, so an unchosen one fell through to [`Depth::Flat`] and no renderer
51 //! drew it; goingson's tab strip recesses its unchosen tabs by hand and could
52 //! not delete the line, because being recessed is *why* the chosen tab reads as
53 //! coming forward. So [`Selector::unchosen`] joins `chosen`, and saying it
54 //! needed [`Fill::Sunken`] and [`Depth::Sunken`]: a surface set back by colour
55 //! with no edge, which is neither a well nor level-with.
56 //!
57 //! 0.7.0 adds [`State`], the interaction axis, closing the gap that adopting
58 //! against three apps rather than one made visible. The description named
59 //! rest and, through [`Depth::pressed`], pressed. It named neither focus nor
60 //! disabled, so `makeover-webview` emitted a hover rule and stopped, and each
61 //! consumer completed the primitive from outside by out-specifying a rule it
62 //! did not own: 19 such rules in goingson, 21 in the MNW server, a further set
63 //! in Balanced Breakfast, and three focus rings that do not match. The axis is
64 //! deliberately two members wide, because hover and pressed belong where they
65 //! already are. [`State`]'s own docs carry that argument.
66 //!
67 //! 0.8.0 finishes [`Field`], which described a field well enough to label it and
68 //! not well enough to draw it. Writing `makeover-webview`'s form emitter found
69 //! three things missing and the renderer supplied all three from outside: the
70 //! current value, a select's options, and the placeholder. Two of those move
71 //! here and one does not.
72 //!
73 //! - [`Field::placeholder`] is user-facing text sitting beside `label` and
74 //! `hint`. There was never a reading on which it was renderer state; it was
75 //! outside only because adding a field to a published struct is breaking.
76 //! - [`Field::options`] moves because every renderer needs them and each was
77 //! going to invent its own shape. [`Choice`] is the shape `makeover-webview`
78 //! already arrived at, taken as-is rather than redesigned.
79 //! - The current value stays renderer-side and is not coming here. It is the
80 //! one of the three that is genuinely state: a webview reads it out of the
81 //! DOM, an immediate-mode renderer holds a `&mut` to the app's own field, and
82 //! a description that carried it would be a form model.
83 //!
84 //! 0.9.0 opens [`RowPart`], which was the last closed enum in the vocabulary,
85 //! and adds [`RowPart::Tokens`]. Both halves come from the same finding, made
86 //! by the first two real screens described through the router rather than by
87 //! reading a stylesheet.
88 //!
89 //! A goingson project card carries two trailing badges, a type and a toned
90 //! status; a contact card carries a primary email *and* a strip of tags. `Meta`
91 //! is one slot and one string, so both ports joined their facts with a
92 //! separator and lost what the second one was: a status reads as text where it
93 //! used to read as colour. [`Token`] already says exactly the right thing — a
94 //! small labelled thing with a kind, a tone and an optional action — and could
95 //! only ever be a node in its own right, never inside a row.
96 //!
97 //! So the missing thing was permission rather than a concept. `Tokens` is that
98 //! permission, and `#[non_exhaustive]` arrives with it so the next member is not
99 //! a lockstep event across three renderers. The pairing is the point: this
100 //! enum's own consumer in `makeover-webview` carried a comment predicting it
101 //! would stop compiling one day, which is a lockstep break written down and
102 //! waited for rather than prevented.
103 //!
104 //! Balanced Breakfast was checked before the member was added, because one
105 //! consumer wanting something is not evidence. It packs a count and two icon
106 //! buttons into the same single `Meta` slot while leaving `Actions` empty, so
107 //! the slot was already straining under a second consumer for a different
108 //! reason.
109 //!
110 //! 0.10.0 adds [`Meter`], a proportion carried as a pair rather than as a
111 //! percentage. Its own docs carry the argument; the short form is that the
112 //! percentage shape had already been tried in goingson and had already needed a
113 //! companion flag to recover what rounding and clamping threw away.
114 //!
115 //! 0.11.0 is four members from the quasi proving ground, batched into one
116 //! release because pre-1.0 a minor is breaking and a cascade is nine repos.
117 //! Three findings that arrived with them turned out not to belong here at all:
118 //! this crate has no notion of an action, a route or a destination, so anything
119 //! asking what a control *calls* was never the vocabulary's to say.
120 //!
121 //! - [`Figure`], a value with a caption. goingson had five of them across five
122 //! screens with five class vocabularies for the one shape, which is the
123 //! divergence this crate exists to end, sitting in plain sight and counted for
124 //! the first time.
125 //! - [`RowPart::Proportion`], so a [`Meter`] can sit in a row. `Meter` reached
126 //! two of its seven sites at 0.10.0 and the other five are row-shaped. Exactly
127 //! [`RowPart::Tokens`]'s problem with a different payload, and it takes
128 //! `Tokens`' answer: the part carries the description of a bar, not a node.
129 //! - [`Field::max_length`], [`Field::min`] and [`Field::max`], joining
130 //! [`Field::required`], which had been sitting here as the sole constraint
131 //! while the header above claimed there were none. The set stops before
132 //! `pattern`, which fails the renderer test and is one site in one app.
133 //! - [`FieldKind::File`]. Every host has an honest answer — a native picker, an
134 //! `<input type="file">`, a path prompt, an argument — and it carries no
135 //! accepted-types list because `accept` appears at zero sites in either app.
136 //!
137 //! The evidence rule changed under these, and it is worth recording because four
138 //! earlier decisions were made under the old one. The two-app test said a shape
139 //! earns a word once a second app wants it. It is backwards: a rule that
140 //! withholds a word until a second app has duplicated the code guarantees the
141 //! duplication, and app three writes it a third time. The bar is now generic
142 //! against bespoke — is this furniture any app would have, or is it this app's
143 //! own? Bespoke keeps [`Region::Bespoke`], which already carries a completion
144 //! heatmap and is the right answer for a calendar nobody will build twice.
145 //!
146 //! 0.12.0 is two more from the same proving ground, and the same sorting
147 //! happened first: six findings came out of a measurement of goingson's whole
148 //! frontend, and four of them turned out to be asking what a control *calls*,
149 //! which this crate cannot say. The two that were really here:
150 //!
151 //! - [`Readiness`] grows from two states to four. It named `Ready` and
152 //! `Pending` and stopped, so a screen whose list came back empty had nothing
153 //! to say about it; goingson draws an empty state at 27 sites and Balanced
154 //! Breakfast at 9. `Empty` and `Failed` are the same axis rather than a new
155 //! member beside it, because a region shows one of the four and never two.
156 //! `#[non_exhaustive]` arrives with them, the pairing [`RowPart`] made at
157 //! 0.9.0 and for the same reason.
158 //! - [`Column::sortable`], [`Column::sorted`] and [`Sort`]. The one finding in
159 //! the set that completes a member rather than adding one: `Column` shipped
160 //! with a width and a priority and could not say that a table is ordered by a
161 //! column, so a described table could draw no caret and offer no reordering.
162 //!
163 //! 0.14.0 is two additive members on two `#[non_exhaustive]` enums, released
164 //! together because publishing twice for that is waste and the cascade below
165 //! this crate is nine repos.
166 //!
167 //! - [`Depth::Overlay`]. The enum could say raised, well, sunken and flat, and
168 //! could not say that a surface sits *over* the page. Every renderer already
169 //! had the surface — `makeover-tui`'s `Palette::overlay`,
170 //! `makeover-immediate`'s `Palette::elevation`, `makeover-webview`'s
171 //! `--elevation-overlay` — and none of them could be reached from a
172 //! description. buckets_of_money has 16 modals waiting on it.
173 //! - [`CellPart`], which is [`RowPart`] for tables. A row's parts have carried
174 //! their own content intent since 0.2.0, so `.row-actions` inherits rather
175 //! than taking a text colour; a table cell had no such vocabulary and
176 //! `makeover-webview` emitted one undifferentiated `.cell`, so a button in a
177 //! cell was painted as text. The four members are the four things quasi's
178 //! `Cell` was measured to hold, and the count is in that crate's history
179 //! rather than assumed here.
180 //!
181 //! 0.15.0 adds [`FieldKind::Date`] and [`FieldKind::DateTime`], on the argument
182 //! [`FieldKind::Email`] was admitted on: a webview emits a different `type=`,
183 //! which is a native picker, the platform's validation and a different keyboard
184 //! on a touch device. Described as text with a "YYYY-MM-DD" hint, all three are
185 //! lost.
186 //!
187 //! Two members and not one or five, from a count rather than from symmetry: 13
188 //! sites of `date` and 13 of `datetime-local` across the MNW server and
189 //! goingson, and zero of `time`, `month` or `week`. The wire format each takes
190 //! is named here as [`DATE_FORMAT`] and [`DATETIME_FORMAT`], because a host
191 //! left to pick its own would disagree with a server silently, and
192 //! [`FieldKind::temporal`] is the pair asked about once rather than at each
193 //! renderer. `FieldKind`'s own comment claiming `radio` was the last HTML input
194 //! type missing was already false when 0.8.1 wrote it; these are what it was
195 //! missing.
196 //!
197 //! What each of the 0.12.0 findings deliberately leaves out is the address — what pressing a
198 //! header calls, and where an empty state's "Add your first project" button
199 //! goes. That is the boundary this crate is defined by, and four findings moved
200 //! across it rather than being answered here.
201 //!
202 //! 0.19.0 narrows [`State`] to [`State::Disabled`] alone. `State::Focus` is
203 //! gone: a description never states what has focus, because what focus *is*
204 //! differs per host and every renderer had already decided for itself — the
205 //! webview draws it from `:focus-visible`, egui refused the variant outright,
206 //! and quasi-tui honoured it once at startup and overrode it thereafter.
207 //!
208 //! 0.20.0 adds [`Region::Widget`], the third tier, and `#[non_exhaustive]` to
209 //! [`Region`] with it. Every vocabulary finding until now had two answers
210 //! available — grow the primitive set, or [`Region::Bespoke`] — and a whole
211 //! class of thing is wrong for both. A carousel is not a primitive, because a
212 //! terminal has none and that is the test `Node::Html` failed. It is not
213 //! bespoke either, because bespoke is what one app owns and every part of a
214 //! carousel is furniture plus members this crate already has.
215 //!
216 //! The cost of the binary was that refusing a primitive was expensive: the app
217 //! hand-rolls the thing forever, so the pressure always ran toward growing the
218 //! primitive set with one host's idioms. A named assembly changes what "no"
219 //! costs without changing what the vocabulary can say.
220 //!
221 //! MNW's carousel is the first consumer and was the finding that started it: one
222 //! partial, three pages, an ordered set of frames with a position, prev/next and
223 //! a dot strip, all of it sayable already and none of it nameable. See wiki
224 //! `widget-tier` for the ownership model, which is why this member carries a
225 //! name a renderer may decline to know.
226 //!
227 //! 0.21.0 adds [`Image`] and [`Fit`], found by trying to describe MNW's
228 //! carousel under 0.20.0's widget tier and getting one step in. Nothing named a
229 //! picture. The vocabulary could say a number with a caption, a badge, a meter
230 //! and a table, and could not say the thing three of MNW's public pages are
231 //! mostly made of.
232 //!
233 //! It reads as an oversight and is a measurement: 24 `<img>` sites across 22
234 //! MNW templates, against one in goingson and none in Balanced Breakfast or
235 //! audiofiles. A picture is furniture a *content platform* has, and MNW is the
236 //! only one in the tree, so the evidence never arrived from the two-app
237 //! direction the earlier rule looked in. Under the generic-against-bespoke bar
238 //! it is not close: a picture is not one app's own.
239 //!
240 //! A primitive rather than a widget, which is worth stating now that the tier
241 //! makes it a real question. A widget is an assembly of things already sayable
242 //! and a picture is a leaf, assembled from nothing. It also passes the test
243 //! `Node::Html` failed — every host has an honest answer, including a terminal,
244 //! which has a graphics protocol or has [`Image::alt`].
245 //!
246 //! [`Image`] carries no source, the split [`Act`] already makes: an address is
247 //! not this crate's to hold. See its own docs, which is where the argument is.
248 //!
249 //! 0.22.0 finishes [`Image`], which 0.21.0 shipped unable to say how much room
250 //! a picture needs. Without that a renderer cannot reserve space, so a picture
251 //! occupies nothing until its bytes arrive and then takes its full height at
252 //! once. Measured on MNW's landing page: a 478px jump per frame and a
253 //! cumulative layout shift of 0.087 for the page.
254 //!
255 //! - [`Image::intrinsic`], the picture's own dimensions, carried as [`Extent`].
256 //! A fact about the asset rather than a display size, which is what keeps it
257 //! on this side of the deferral rule: 5120x3412 is what the file *is*, and no
258 //! renderer can learn it without fetching the bytes.
259 //! - [`Loading`], and the default flips to [`Loading::Eager`]. 0.21.0 emitted
260 //! the webview's `loading="lazy"` for every picture, which read one
261 //! consumer's habit as a rule. Deferring a picture that is on screen at first
262 //! paint saves nothing and makes its shift land later. The carousel is the
263 //! case that proves this cannot be one renderer-wide setting: its first frame
264 //! is on screen and its others are not, in one widget, at one moment.
265 //!
266 //! 0.23.0 adds [`Showing`], which is three open findings collapsing into one
267 //! member. A tab group could not say which tab was open, a carousel could not
268 //! say which frame was up, and a disclosure could not say whether its child was
269 //! showing. All three are the same missing sentence, and while it was missing a
270 //! renderer had two moves: match on a widget name, or draw every child.
271 //!
272 //! So the widget tier was taking the blame for a gap one level below it. With
273 //! this a renderer derives its chrome from the description — labels get a strip,
274 //! no labels get previous/position/next — once, for every widget there will ever
275 //! be, and [`Region::Widget`]'s name goes back to being app vocabulary a
276 //! renderer may decline to know.
277 //!
278 //! Only the kind lives here. Which child is up, and what each child is called,
279 //! sit with whatever holds the regions, the same split [`Selector`] already made
280 //! against `Node::Select`.
281 //!
282 //! 0.27.0 adds [`Region::Group`], which closes a gap this crate had carried
283 //! since 0.2.0 without noticing: [`Heading::Section`] is documented as naming a
284 //! block within the screen, and there was no block. A section heading is a leaf
285 //! beside the things it names, so the description could say a section had
286 //! *started* and never that one had ended.
287 //!
288 //! Found by asking how a screen distinguishes groups of settings by colour, and
289 //! the answer turned out to be two findings rather than one. This is the first
290 //! and it is the precondition: there is nothing to tint until there is a
291 //! container. The second — every renderer already resolves `category.one`
292 //! through `category.six` and no description can reach any of them — is filed
293 //! and not shipped here.
294 //!
295 //! What the colour question settled anyway, because it shapes this member: the
296 //! group carries no colour and no ordinal. A renderer distinguishing sibling
297 //! groups derives the assignment from their order, which is
298 //! [`Region::Columns`]' reasoning about counts applied to colour — the children
299 //! say, and a value here would be a second source for something the description
300 //! already states by containing them.
301 //!
302 //! 0.28.0 is what audiofiles' forms port found it could not say, three findings
303 //! filed against a working conversion rather than guessed at in advance. All
304 //! three are about a *question* rather than about a control, which is the line
305 //! this crate keeps having to redraw.
306 //!
307 //! - [`FieldKind::Range`] and [`Field::step`]. A bounded number the user drags
308 //! across, where both ends being on screen is what the question means. The
309 //! reading to resist is that this is [`FieldKind::Number`] with bounds, and it
310 //! is [`FieldKind::Radio`]'s argument again: a validated number can be out of
311 //! range and a slider cannot, so the bounds stop being a rule and become the
312 //! control's extent. [`Field::bounded`] is the check a renderer asks, since a
313 //! range missing an end has nothing to draw.
314 //! - [`Choice::unavailable`]. An option that is real, worth showing, and cannot
315 //! be picked yet. Without it an app either drops the option — and the user
316 //! never learns it is there — or hand-rolls the control outside the
317 //! description, which is what audiofiles' instrument panel did: a permanently
318 //! disabled radio plus a hand-written line saying what would enable it.
319 //! `#[non_exhaustive]` arrives on [`Choice`] in the same release, so this is
320 //! the last breaking addition to it.
321 //! - Not a member at all: [`Field::placeholder`] on a chooser. It was sayable
322 //! already and no renderer read it, so a select with nothing chosen showed an
323 //! empty box and the instruction lived on a disabled button elsewhere. The
324 //! renderers moved, not the description.
325 //!
326 //! 0.29.1 adds [`Awaiting`], which is the sentence [`Readiness`] could say about
327 //! a region and could not say about a control. A described screen could state
328 //! that a list was on its way and could not state that the button just pressed
329 //! is doing the thing it was pressed for, so every renderer's in-flight
330 //! treatment was the app's to hand-write. The MNW server hand-writes it 57 times
331 //! and hand-writes the guard against a second press twice, which is the half
332 //! that matters going missing on a codebase that sells things.
333 //!
334 //! The mark is the fact that something outstanding will complete, once, in
335 //! expected finite time. Deliberately not remoteness, since a heavy local query
336 //! waits too, and deliberately not slowness, which is a judgement rather than a
337 //! property. It carries an optional amount, stated only when the amount is
338 //! measured, and it carries no duration at all: a renderer draws what is done
339 //! over what there is plus the time so far, and never an estimate of what is
340 //! left.
341 //!
342 //! One mark and two readings, which is what keeps a slow region from being
343 //! hand-split into its own route the way MNW's payout summary is: a pressed
344 //! control goes busy and locks, a region fed by an awaiting call stands in as
345 //! [`Readiness::Pending`] and fills when it lands.
346 //!
347 //! A patch release for a new member, which is the 0.27.5 precedent rather than a
348 //! new rule: nothing existing changed shape, so every consumer already asking
349 //! for 0.29 keeps resolving and the suite below this crate does not have to move
350 //! for a type only quasi reads. The minor releases above were minor because they
351 //! also narrowed something.
352 //!
353 //! 0.30.0 is two members batched into one release, which is 0.11.0's precedent
354 //! and its reasoning: pre-1.0 a minor is breaking, the cascade below this crate
355 //! is seven repos, and paying that twice in a week for two unrelated words is
356 //! the tax the batching exists to avoid.
357 //!
358 //! - [`FieldKind::Rich`], a field whose value is markdown source. The editing
359 //! counterpart of prose already carried as markdown, and it is renderable
360 //! everywhere for the reason the carrying is: editing markdown is editing
361 //! text. It buys a renderer permission to offer a preview or a syntax pass and
362 //! buys a host reading the value back the knowledge of what it holds; a
363 //! renderer with neither draws a textarea. It says nothing about when the
364 //! value is saved, because autosave is a clock. Measured against four MNW
365 //! section editors that are one shape written four times.
366 //! [`FieldKind::multiline`] arrives with it, since the pair is now two members
367 //! every renderer has to ask about.
368 //! - [`Facet`], [`Selecting`], [`FacetValue`] and [`Standing`]: a named
369 //! dimension a set is narrowed by. MNW's discover page filters six ways
370 //! through six mechanisms, and its filter rows carry a tick box *and* a
371 //! chevron only because a tag's selection and a tag's browse position were
372 //! held separately. One word covers all six, and [`Selecting::Subtree`] is the
373 //! member that made it an enum rather than a bool: a tree's selection is
374 //! branches taken and branches pruned, which no flat mode can express, and
375 //! making one gesture do browsing and filtering together is what lets the
376 //! second mechanism go. [`Standing`] has four members rather than a bool for
377 //! the tree's sake — a value in force because an ancestor is, is not a value
378 //! somebody picked. [`FacetValue`] splits an identifier from a label for
379 //! [`Choice`]'s reason and one of its own: two leaves under different parents
380 //! are legitimately both called "Ambient", and the path is what tells them
381 //! apart and what nearest-ancestor-wins resolves over. Deliberately wider than
382 //! that one page: audiofiles' library browser and goingson's filters are the
383 //! same shape.
384 //!
385 //! 0.35.0 gives a suggestion its second line. [`Candidate`] is the entry in a
386 //! field's suggestion list: a value, a label, and the [`detail`] that orients
387 //! it. Ruled by Max 2026-08-21 (`1fcf2e9b`) after the combobox member shipped
388 //! and was then held against the two sites it was designed from, which is an
389 //! order worth not repeating.
390 //!
391 //! - **A candidate is not a [`Choice`], and the difference is in the reading
392 //! rather than the writing.** Both submit one string and read as another. An
393 //! option is picked out of a set the user can see whole; a candidate is
394 //! offered out of a set nobody can see, so it has to say what tells it from
395 //! its neighbours. Both measured sites draw that second string today, by
396 //! hand, in a second span.
397 //! - **It is its own type rather than a member on [`Choice`].** `Choice` is the
398 //! most-consumed struct in the vocabulary and the member would have landed on
399 //! every option list in the tree the day it shipped, including the ones with
400 //! nowhere to draw it.
401 //! - **[`Candidate`] is `#[non_exhaustive]` from birth**, which is the whole of
402 //! what 0.28.0 cost and is not being paid twice.
403 //! - No `unavailable`. A suggestion that cannot be picked is a row a route
404 //! should not have offered.
405 //!
406 //! [`detail`]: Candidate::detail
407 //!
408 //! 0.34.0 gives an interval a description. [`FieldKind::Interval`] and
409 //! [`Field::upper_name`] say that two values are one question with two ends.
410 //! Ruled by Max 2026-08-21 against audiofiles' six filter axes and the MNW
411 //! server's price pair, which is HTML saying the grouping in an ARIA
412 //! `role="group"` and nowhere else.
413 //!
414 //! - **The ends constrain each other, and nothing else in the vocabulary could
415 //! say so.** Two [`FieldKind::Number`] fields are two questions: a renderer
416 //! draws two labels with no relationship, and [`Field::error`] attaches to one
417 //! side of a fault that belongs to both.
418 //! - **It is not [`FieldKind::Range`]**, which is the reading to resist and the
419 //! same resistance `Range` needed against `Number`. A range is one value
420 //! inside an extent; this is two, and the extent is a bound on each rather
421 //! than the question's meaning.
422 //! - **Both names are stated rather than derived.** Measured the same day, the
423 //! two sites disagree about affix order -- `bpm_min`/`bpm_max` against
424 //! `min_price`/`max_price` -- so any rule renames one of them. One member
425 //! instead of a naming convention this crate would own forever, and which
426 //! member a name sits in is what says which end it is.
427 //! - The crossing rule is not enforced, exactly as [`Field::min`] is not. What
428 //! the description buys is one place to report the fault rather than two.
429 //!
430 //! [`Field::upper_name`] is a member on a struct that is not
431 //! `#[non_exhaustive]`, so this is a formal break for crates.io and zero
432 //! call-site edits in the tree: every literal builds on a constructor.
433 //!
434 //! 0.33.0 gives a number its unit. [`Field::unit`] carries what the value is
435 //! measured in, and [`FieldKind::measurable`] says which kinds read it. Decided
436 //! by Max 2026-08-21 (`32215e21`) against eight sites across four audiofiles
437 //! files that had each independently put the unit in parentheses at the end of
438 //! the label -- three of them written while the gap was a known open question.
439 //!
440 //! - **A unit is a fact about the value, not part of the question's name.** The
441 //! two readings come apart the moment anything reads a field back rather than
442 //! drawing it, which is the argument that decided it.
443 //! - **The convention it replaces froze the worst placement.** A label is the
444 //! sentence above the control, so unit-in-label was the same answer on every
445 //! host -- including the host that had somewhere better, since egui's slider
446 //! already draws a suffix beside the readout, which is what these controls did
447 //! before they were described.
448 //! - A string rather than a closed family, which is [`Curve`]'s argument
449 //! inverted and correctly so: a curve is a mapping this crate computes, and a
450 //! unit is a symbol it only carries. The measured set is `GiB`, `dBFS`, `s`
451 //! and `ms`, and this crate does not know what the next consumer measures in.
452 //!
453 //! Additive: absent is what every field meant before.
454 //!
455 //! 0.32.0 is the slider's real shape. **The data of a slider is a fraction and
456 //! a function taking numbers to numbers** (Max, 2026-08-21), so [`Curve`]
457 //! arrives and [`Field::curve`] with it. [`Field::min`] and [`Field::max`] were
458 //! never the control's extent: a slider's extent is always 0 to 1, and the
459 //! bounds are `f(0)` and `f(1)`. Linear is the constant-slope case, which is
460 //! why the mapping was invisible — under it the extent and the bounds coincide
461 //! numerically — and why four renderers each hard-coded it without anyone
462 //! deciding to.
463 //!
464 //! - It is not a scale flag on a range. The question this replaced asked
465 //! whether to name a decoration; what was unnamed is half of what a slider
466 //! *is*, which is why the member is a mapping and not an adjective.
467 //! - **The step spacing rides on the curve.** Max, in the same breath: if the
468 //! family is prescriptive anyway, the granularity belongs in it. On a slider
469 //! the two are one decision, and holding them apart is what let a 0-to-1
470 //! threshold ship as a two-position control. [`Field::step`] narrows to the
471 //! *typed* kinds, where there is no mapping to decide with.
472 //! - A closed family rather than `fn(f64) -> f64`, which is the literal reading
473 //! and does not cross the description boundary: a fn pointer cannot be
474 //! emitted into a browser and cannot be compared or hashed meaningfully,
475 //! which [`Field`] needs. Nothing measured wants an arbitrary function — one
476 //! non-linear shape across five controls, and no second shape.
477 //! - The mapping computes here rather than in each renderer
478 //! ([`Curve::value_at`], [`Curve::position_of`]), so a terminal's bar, an
479 //! egui slider and a browser's input cannot disagree about where a value
480 //! sits. This crate otherwise describes rather than computes; four copies of
481 //! two formulas is the cost of holding that line here.
482 //!
483 //! Additive: [`Curve::Linear`] with no step is what every range meant before,
484 //! so no existing site changes meaning. Consumers: audiofiles' ADSR envelope
485 //! (three logarithmic times) and its storage cap picker.
486 //!
487 //! 0.31.0 finishes the file field. [`FieldKind::File`] arrived at 0.11.0
488 //! carrying neither an accepted-types list nor a multiplicity flag, and said so
489 //! in its own doc: `accept` appeared at zero sites in either app, and a member
490 //! added for a case nobody has is a member designed against nothing. That count
491 //! was taken over goingson and Balanced Breakfast, and the MNW server is a third
492 //! consumer with 14 `accept` lists across 10 templates and 4 of its 16 file
493 //! inputs marked `multiple`. The reasoning was right and the measurement went
494 //! stale, so [`Field::accept`] and [`Field::multiple`] arrive now.
495 //!
496 //! - [`Accepted`] is an enum rather than the comma-joined string the templates
497 //! hold, because the list is read twice and only one of the readings is
498 //! filtering. The other is which disclosure to offer — a preview, a duration,
499 //! a waveform — and a renderer deciding that from raw strings is three
500 //! renderers each writing a media-type parser. [`Accepted::family`] answers it
501 //! once. All three shapes are in the measured sites and none can be dropped:
502 //! `image/*` is a [`Family`], `image/jpeg` and `text/csv` are a
503 //! [`Type`](Accepted::Type), and `.zip`, `.tar.gz` and `.clap` are a
504 //! [`Suffix`](Accepted::Suffix). One site carries `.csv,text/csv`, which is
505 //! both in one list.
506 //! - A suffix carries no family and this crate will not infer one. `.mp3` is
507 //! audio in fact, and a table here saying so is a mapping that rots in a
508 //! published crate and is wrong for the first container format someone hands
509 //! it. A call site that wants the disclosure writes the family or the media
510 //! type, which is what the sites offering previews already do.
511 //! - There is one upload shape, not one per type. What a media upload shows
512 //! beyond a plain one is disclosure layered on this shape, which is why the
513 //! accept list is load-bearing beyond validation and why nothing here names a
514 //! media upload as its own kind.
515 //! - Progress is not a member and needs none. An upload in flight is a control
516 //! in flight with a number attached, so it is [`Awaiting`] with the file's
517 //! length as its [`amount`](Awaiting::amount) — the case that type's own doc
518 //! names. Where the bytes go is an address, and this crate holds none; that is
519 //! the router's [`Action`], which the field already points at when it writes
520 //! on its own.
521 //!
522 //! # Reach, focus and the focus ring
523 //!
524 //! Three terms, and no others, for what 0.19.0 moved out of the description.
525 //! **Reach** is which things can take focus and in what order; a browser reads
526 //! it off the document, a TUI derives it from draw order, egui from its own id
527 //! stack. **Focus** is which reached thing has the keyboard right now: the
528 //! renderer's, live, never described and never round-tripped through a
529 //! description. The **focus ring** is the visible cue; the token (`focus-ring`,
530 //! derived by `makeover` from the action colour) is the one shared artifact and
531 //! the drawing is the renderer's. Retired as names for any of this: "focus
532 //! stroke", "focus cue", "wants focus". "Caret" is a different thing — the text
533 //! cursor inside a field — and keeps its name.
534 //!
535 //! # The three tones, and what a colour claims
536 //!
537 //! One rule, settled 2026-08-16, for how colour says whether a thing can be
538 //! used. Every renderer answers to it, and it is stated here because the
539 //! description is what names the intents.
540 //!
541 //! | the thing | intent |
542 //! |-----------|--------|
543 //! | active, emphasised, the thing itself | `content` |
544 //! | inactive but usable: it still answers a press | `content-secondary` |
545 //! | inert: disabled, or not a control at all | `content-muted` |
546 //!
547 //! `content-muted` is the one with a claim in it. [`State::Disabled`] resolves
548 //! to it, so a live control wearing it is telling the user it will not answer —
549 //! and being wrong about that is worse than being quiet, because the user's
550 //! response is to stop trying. A sortable column heading that was never sorted,
551 //! and every unchosen option in a radio group, both read as dead lists that way;
552 //! those are the two this rule was written out of. What is legitimately muted is
553 //! a caption, a hint, a placeholder, a meter's reading, an axis label: text that
554 //! was never going to answer anything.
555 //!
556 //! The three are one ramp and not three colours. `makeover`'s `Emphasis` derives
557 //! the quieter two from the ink, so "one step back" means the same distance in
558 //! every theme and a renderer cannot land between them by picking its own.
559 //!
560 //! # First paint is final paint
561 //!
562 //! One rule, settled 2026-08-16. Nothing may change size or position after it is
563 //! first drawn, and nothing may stand in for content that has not arrived yet.
564 //! Both halves are absolute.
565 //!
566 //! It is stated here, rather than left to each renderer, because a renderer can
567 //! only reserve space the description gave it enough to size. A member whose
568 //! size depends on its content therefore owes whatever makes it sizeable while
569 //! the content is still absent, and that is the second admission test for a new
570 //! member: not only does it compose something this crate already names, it can
571 //! be laid out before it is filled.
572 //!
573 //! The mechanism is a reservation, and [`Sort`]'s caret is the worked example.
574 //! The caret is drawn into a box its own width whether or not the column is
575 //! sorted, so pressing a heading cannot reflow the row it sits in. The box names
576 //! no magnitude, which is what keeps it out of `makeover-geometry`'s territory.
577 //! Reserve from what is known; never discover geometry from what has not
578 //! arrived.
579 //!
580 //! The trap is an `Option` that means "not yet". [`Readiness::Pending`] is the
581 //! honest way to say a region is still waiting. An optional *measurement* is
582 //! not: a count that shows up later widens the text that prints it and moves
583 //! everything beside it, which is the reflow this rule exists to forbid. So an
584 //! `Option` on a measurement means the host will never know it — a property of
585 //! the query, fixed for the life of the screen — and a renderer sizes for the
586 //! answer it was handed rather than for the one it hopes is coming.
587 //!
588 //! # Any width, one answer
589 //!
590 //! The sibling of the rule above, and settled the same day. That one is
591 //! independence from *when*; this one is independence from *how you got here*.
592 //!
593 //! A rendering is a pure function of the description and the viewport. The same
594 //! description at the same width is the same output, whatever widths came
595 //! before it. No renderer may carry geometry across frames, and none may narrow
596 //! by counting.
597 //!
598 //! The failure this forbids is ordinary enough to be the default everywhere
599 //! else: a page that hides its sidebar below some width, remembers that it hid
600 //! it, and does not bring it back the same way. Layout there is a function of
601 //! `(width, history)`, so dragging a window to 900 wide is a different screen
602 //! depending on whether you came from 1400 or from 600. Nobody chose that; it
603 //! is what measuring and remembering produce.
604 //!
605 //! The mechanism is [`Width`] for what grows and [`Priority`] for what drops.
606 //! Both are declared, both are read off the description, and neither needs a
607 //! measurement. A renderer narrows by raising a cutoff over a total order,
608 //! never by counting what fits and stopping — `makeover-tui`'s table states
609 //! that as its own rule and tests it, and `makeover-webview` reaches the same
610 //! place with `@media` and `display: none`, which is path-independent by
611 //! construction because CSS has nowhere to keep the previous width.
612 //!
613 //! Two things follow for anything new. A member that would need last frame's
614 //! size to lay out this frame is refused, the same way a member that cannot be
615 //! sized before it is filled is refused. And a fact about what disappears
616 //! belongs in the description, because a host that has to infer it can only
617 //! infer it from a measurement.
618 //!
619 //! # Where the description stops
620 //!
621 //! The rule is that a member is added when an app needs a fact the vocabulary
622 //! cannot state, and refused when what it wants is presentation it should be
623 //! asking a renderer for. That is the whole test. It is not a quota, and the
624 //! goal is every screen described.
625 //!
626 //! ## What the timeline refusal got wrong, 2026-08-15
627 //!
628 //! This section used to read "a day-plan timeline, a kanban board and a
629 //! calendar are not describable here and will not become describable", and it
630 //! propagated: 12 files across three apps, three libraries and the design wiki
631 //! cited it, including audiofiles and the MNW server, neither of which has a
632 //! timeline. It is withdrawn, and [`Track`] is the member it was refusing.
633 //!
634 //! The error was pricing. The argument assumed a timeline needs a component
635 //! library's worth of vocabulary, and nobody measured it. Held against
636 //! goingson's `day-planning-render.js`, the members it actually needed and
637 //! could not get were two integers: where a thing starts, and how long it
638 //! lasts. Labels, gridlines, item bodies and tones were all furniture this
639 //! crate already named. A refusal that expensive should have carried a
640 //! measurement, and did not.
641 //!
642 //! The reasoning underneath it survives and is still the test: slot heights,
643 //! gridline colour, how overlapping things stack, which hour scrolls into view.
644 //! Those are presentation, they stay the renderer's, and [`Track`] carries none
645 //! of them. What changed is the conclusion, not the principle.
646 //!
647 //! ## The other two, measured 2026-08-15
648 //!
649 //! The same sentence refused a kanban board and a calendar. Both were counted
650 //! the way the timeline should have been, and neither came out where the
651 //! refusal put it.
652 //!
653 //! **Kanban: one member, and it is [`Region::Columns`].** Held against
654 //! goingson's `tasks-kanban.js`, every card fact was already sayable — title,
655 //! project, due date, the blocked and unblocks badges, subtask progress, the
656 //! open action and the context menu are `Row`'s existing parts. A column is a
657 //! heading, a count and a list. What nothing could say was that the columns are
658 //! *peers*: [`Arrangement`] offers list-detail and sidebar-content, and a board
659 //! described as either is a lie about the screen. Dragging a card between
660 //! columns never entered into it — a drop's effect is "set status", a discrete
661 //! action `Row`'s menu already carries, and the drag itself is affordance.
662 //!
663 //! **Calendar: no members, no consumer, and a sharper reason (Max,
664 //! 2026-08-15).** The month grid's primacy in calendar apps is an artifact of
665 //! paper: paper cannot be queried, so it has to show every day at once as a
666 //! fallback index. Routes, search and ranking do that job better, which is the
667 //! argument `events-calendar.js` already lost to a segmented list on
668 //! 2026-08-11.
669 //!
670 //! Three jobs survive that reasoning, and only one of them needs a grid:
671 //!
672 //! 1. **Spans across days** — a stretch of leave, a trip, a sprint. You cannot
673 //! see "away the 3rd to the 17th" in a list without diffing dates. This is
674 //! [`Track`] with [`Unit::Days`], not a calendar, and
675 //! [`Track::days`] is it.
676 //! 2. **Density at a glance** — which weeks were heavy. That is a heatmap, and
677 //! goingson describes both of its heatmaps as lists already.
678 //! 3. **Weekday periodicity** — "every other Tuesday", "the 15th is a
679 //! Saturday". This is the only job that needs the seven-column wrap, because
680 //! alignment is the whole of what makes it visible.
681 //!
682 //! So the open question is not "is a calendar describable" but "is job 3 worth
683 //! a member", and nothing in the tree asks for job 3 yet. GoingsOn
684 //! quasicoherent `4a1237b6`.
685 //!
686 //! A month grid renders today as a
687 //! [`Table`](crate::Column): seven weekday columns, weeks as rows, blanks for
688 //! the offset. goingson's monthly review reached this conclusion before this
689 //! note did and describes its month as a list of days that had something on
690 //! them, marking today with an ordinary badge. What the tree actually contains
691 //! is two completion heatmaps — one scalar per day — and no calendar at all:
692 //! `events-calendar.js` was deleted 2026-08-11 in favour of a segmented list,
693 //! and no MNW template mentions one. So the refusal was defending a screen
694 //! nobody has. If one is built, measure again; the facts already fit and only
695 //! the grid's shape would be in question.
696 //!
697 //! The pattern worth keeping from all three: one sentence refused three things
698 //! for one reason, and the reason was wrong three different ways. Count the
699 //! members.
700 //!
701 //! [`Region::Bespoke`] remains for the genuinely app-owned, and its
702 //! justification does not depend on the withdrawn claim. The
703 //! description names the *place* and the app owns the contents, so a screen
704 //! containing a timeline is still a whole screen and still routable. Without
705 //! it, the four goingson screens that make the app worth using would need a
706 //! second, undescribed path beside the router, and two paths is how a
707 //! vocabulary starts drifting from its app again.
708 //!
709 //! [`Region::Widget`] sits between that limit and the primitives, and it does
710 //! not move the limit. A widget is an assembly of members this crate *already*
711 //! has, under a name a renderer may or may not recognise. Anything that needs a
712 //! member the vocabulary does not have is still a finding about the vocabulary
713 //! or still bespoke; naming an assembly buys no new expressive power, which is
714 //! exactly why it is safe to let the set grow outside this crate.
715
716 #![forbid(unsafe_code)]
717
718 /// A colour intent this crate refers to but never resolves.
719 ///
720 /// The string is the token name `makeover` publishes, so a renderer can look
721 /// it up without this crate knowing what colour came back.
722 pub trait Intent {
723 /// The `makeover` intent token this resolves against.
724 fn token(self) -> &'static str;
725 }
726
727 /// Which way the light falls across a two-tone edge.
728 ///
729 /// The whole content of a bevel, once colour and thickness are deferred. The
730 /// light is always assumed to come from the top left: every consumer measured
731 /// agreed on that and none of them ever varied it, so it is an invariant here
732 /// rather than a parameter.
733 ///
734 /// # The two corners that belong to both edges
735 ///
736 /// Top-right and bottom-left are where the lit run meets the shaded one, and
737 /// the description's claim is that they belong to *both*. How a renderer says
738 /// that is its own business, because the answer is bounded by resolution and
739 /// not by taste:
740 ///
741 /// - A terminal cell is roughly 8x17 device pixels, so giving the whole corner
742 /// to one tone thickens that edge by a cell and reads as one run overrunning
743 /// the other. A half-cell glyph divides the cell already, so `makeover-tui`
744 /// splits it and recovers real information. Its box-drawing fallback cannot:
745 /// a single stroke has no half to give, so there both corners go to dark.
746 /// - A pixel bevel is a one-point stroke by default, which makes the corner a
747 /// one-point square. There is nothing to divide — a diagonal seam across one
748 /// point is sub-pixel, and antialiasing renders it as the blend a mitred join
749 /// already produces. So `makeover-immediate` mitres and is *not* diverging;
750 /// it is the same rule at a resolution where the split degenerates.
751 ///
752 /// Stated here so the difference reads as a decision rather than as drift. A
753 /// renderer with room to divide the corner should; one without should mitre or
754 /// pick the shaded tone, and neither is a bug.
755 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
756 pub enum Bevel {
757 /// Lit from the top left: light on top and left, dark on bottom and right.
758 Raised,
759 /// The same edge inverted, which is also the pressed state of anything
760 /// that draws itself [`Bevel::Raised`].
761 Inset,
762 }
763
764 impl Bevel {
765 /// The edge intents, as `(top_left, bottom_right)`.
766 ///
767 /// Split out from any painting because the inversion *is* the idea, and
768 /// it is the one part every renderer implements identically.
769 #[must_use]
770 pub const fn edges(self) -> (Edge, Edge) {
771 match self {
772 Self::Raised => (Edge::Light, Edge::Dark),
773 Self::Inset => (Edge::Dark, Edge::Light),
774 }
775 }
776
777 /// Pressing inverts. A raised control reads as inset while held.
778 ///
779 /// Stated here rather than left to each consumer because a cascade can
780 /// carry a pressed state and an immediate-mode renderer cannot: audiofiles
781 /// resolves this per call site, eighteen times.
782 #[must_use]
783 pub const fn pressed(self) -> Self {
784 match self {
785 Self::Raised => Self::Inset,
786 Self::Inset => Self::Raised,
787 }
788 }
789 }
790
791 /// One side of a bevel, named by the intent it takes.
792 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
793 pub enum Edge {
794 /// The lit side.
795 Light,
796 /// The shadowed side.
797 Dark,
798 }
799
800 impl Intent for Edge {
801 fn token(self) -> &'static str {
802 match self {
803 Self::Light => "bevel-light",
804 Self::Dark => "bevel-dark",
805 }
806 }
807 }
808
809 /// A surface intent a region is filled with.
810 ///
811 /// `#[non_exhaustive]`, so a renderer must carry a wildcard arm and a new
812 /// member is additive rather than breaking. Added 0.4.0, after [`Sunken`]
813 /// (an additive member, 0.3.0) hard-broke `makeover-tui` and
814 /// `makeover-immediate` at compile time and left neither able to move until
815 /// both published. The vocabulary exists to grow and the renderers exist to
816 /// disagree about how much of it they answer, so growth must not be a
817 /// lockstep event. The renderer's wildcard is not a hole: [`Fill`] is
818 /// resolved through a fallible lookup, and a missing intent is answered with
819 /// structure rather than with a substituted colour.
820 ///
821 /// [`Sunken`]: Fill::Sunken
822 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
823 #[non_exhaustive]
824 pub enum Fill {
825 /// The page behind everything.
826 Page,
827 /// A surface lifted off the page: cards, controls, menus, toasts.
828 Raised,
829 /// A surface floating above the page rather than resting on it.
830 Overlay,
831 /// The inside of a well.
832 Well,
833 /// A surface set back from the one it sits on, by colour and nothing else.
834 ///
835 /// Not a well. A well is a hole with an edge, and the two are authored in
836 /// opposite directions: `makeover` derives `surface-well` by inverting
837 /// against the theme's own content colour, while `surface-sunken` is
838 /// authored and free to sit darker than raised (goingson's does). Naming
839 /// only the well left the recessed-with-no-edge surface unsayable, which is
840 /// what an unchosen tab is: it recedes so the chosen one can come forward,
841 /// and it carries no bevel of its own.
842 ///
843 /// Added 0.3.0, from goingson's tab strip, which hand-writes exactly this
844 /// and could not delete the line because no member described it.
845 Sunken,
846 }
847
848 // No `fallback` here, deliberately. An earlier cut had `Fill::Well` fall back
849 // to `Fill::Page` so a consumer on makeover 2.2.0, which has no `surface-well`,
850 // had something to paint. makeover-tui found that wrong within a day: page is
851 // the surface a well is usually cut into, so on a terminal that substitution
852 // produces exactly the invisibility it was meant to prevent, and the right
853 // answer there is a drawn edge rather than a different colour.
854 //
855 // Substituting one intent for another is renderer policy. The description says
856 // what the region is and stops.
857
858 impl Intent for Fill {
859 fn token(self) -> &'static str {
860 match self {
861 Self::Page => "surface-page",
862 Self::Raised => "surface-raised",
863 Self::Overlay => "surface-overlay",
864 Self::Well => "surface-well",
865 Self::Sunken => "surface-sunken",
866 }
867 }
868 }
869
870 /// How a region sits relative to the surface behind it.
871 ///
872 /// Fill and bevel are named together because naming them apart is what let
873 /// them disagree. Every consumer measured had at least one region carrying a
874 /// raised bevel over a recessed fill: audiofiles fixed it in `raised_frame`
875 /// and recorded the bug in its doc comment, and Balanced Breakfast still had
876 /// twelve of them a year later. A single name for the pair makes that
877 /// unrepresentable.
878 /// `#[non_exhaustive]` for the same reason as [`Fill`], and in the same
879 /// release: a depth this renderer has no drawing for should cost it a
880 /// wildcard arm, not a compile error and a wait on someone else's publish.
881 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
882 #[non_exhaustive]
883 pub enum Depth {
884 /// Level with its surroundings. No edge.
885 Flat,
886 /// A card laid on the panel it sits in.
887 Raised,
888 /// A hole in the panel, with content down inside it. For anything the
889 /// user looks *into*: a table body, a tag tree, a text field.
890 Well,
891 /// Set back from what it sits on, by colour alone. No edge.
892 ///
893 /// The one member carrying a fill without a bevel, so a renderer cannot
894 /// assume the two arrive together. That is deliberate and it is still the
895 /// pairing rule: both halves come off the same `Depth`, so they cannot
896 /// disagree, and here one half is legitimately absent.
897 ///
898 /// Distinct from [`Depth::Flat`], which has no fill either and inherits.
899 /// Recessed and level-with are different claims, and only one of them
900 /// needs a colour.
901 Sunken,
902 /// A surface sitting *over* the page rather than in it. A modal, a popover,
903 /// a menu.
904 ///
905 /// Takes elevation and no bevel: a surface overlaying the page is lifted
906 /// off it, and a surface in the page is cut into it. That is the same
907 /// pairing rule the rest of the enum holds, applied to the one case where
908 /// the separation is not an edge at all — the lift and the scrim behind it
909 /// are already saying where the surface is.
910 ///
911 /// Every renderer had the surface before it had this variant.
912 /// `makeover-tui` carries `Palette::overlay`, `makeover-immediate` gained
913 /// `Palette::elevation` at 0.10.0, and `makeover-webview` emits
914 /// `--elevation-overlay`. What was missing was the route from a description
915 /// to any of them, which is why this is one variant rather than a feature.
916 Overlay,
917 }
918
919 impl Depth {
920 /// The edge this depth is drawn with, if it has one.
921 #[must_use]
922 pub const fn bevel(self) -> Option<Bevel> {
923 match self {
924 // Sunken joins Flat here, for the opposite reason: Flat has no edge
925 // because nothing separates it from its surroundings, and Sunken has
926 // none because its colour is already doing the separating.
927 Self::Flat | Self::Sunken => None,
928 // A third reason to have no edge, which is why it gets its own arm
929 // rather than joining the two above: an overlay is separated by the
930 // lift and by the scrim behind it, so an edge would be a second
931 // answer to a question already answered.
932 Self::Overlay => None,
933 Self::Raised => Some(Bevel::Raised),
934 Self::Well => Some(Bevel::Inset),
935 }
936 }
937
938 /// The surface this depth is filled with.
939 ///
940 /// [`Depth::Flat`] has no fill of its own: it inherits whatever it sits on,
941 /// which is the difference between level-with and painted-the-same-colour.
942 #[must_use]
943 pub const fn fill(self) -> Option<Fill> {
944 match self {
945 Self::Flat => None,
946 Self::Raised => Some(Fill::Raised),
947 Self::Well => Some(Fill::Well),
948 Self::Sunken => Some(Fill::Sunken),
949 Self::Overlay => Some(Fill::Overlay),
950 }
951 }
952
953 /// Pressing a raised region reads as a well, and nothing else moves.
954 ///
955 /// [`Depth::Overlay`] is untouched along with the rest: an overlay is a
956 /// surface, not a control, so there is nothing there to press.
957 #[must_use]
958 pub const fn pressed(self) -> Self {
959 match self {
960 Self::Raised => Self::Well,
961 other => other,
962 }
963 }
964 }
965
966 /// An interaction state a region can be in, beside whatever [`Depth`] it is.
967 ///
968 /// Orthogonal to depth on purpose. A disabled button is still [`Depth::Raised`]
969 /// and a disabled field is still a [`Depth::Well`], so folding either member
970 /// into `Depth` would make [`Depth::bevel`] and [`Depth::fill`] answer for
971 /// something that is not a depth, and would leave disabled-button and
972 /// disabled-field sharing one variant that cannot tell them apart.
973 ///
974 /// # Why hover and pressed are not members
975 ///
976 /// The line is whether every renderer has the state to express, not whether CSS
977 /// does. Hover is renderer policy and `makeover-webview` says so in its own
978 /// header: a terminal and an immediate-mode painter have no pointer hovering
979 /// over anything, and pressed already arrives through [`Bevel::pressed`] and
980 /// [`Depth::pressed`], where it belongs, because pressing is a depth inversion
981 /// rather than a separate condition.
982 ///
983 /// Focus and disabled are different in kind. A TUI has a focused widget and a
984 /// greyed-out one; so does egui. Both were unsayable here, so all three webview
985 /// consumers supplied them from outside the primitive by out-specifying rules
986 /// they did not own: goingson alone carries 19 of them, and the MNW server
987 /// another 21. That is the divergence this crate exists to end, arriving one
988 /// layer down.
989 ///
990 /// # The principle this encodes
991 ///
992 /// A primitive owns every state it implies. A renderer that emits a hover rule
993 /// for a thing owes disabled and the capability answer for that same thing,
994 /// because anything less exports the completion work to N consumers who will
995 /// each do it differently.
996 ///
997 /// Focus is not on that list and was removed from this axis in 0.19.0. It is
998 /// the renderer's, decided after the description; see the crate header, "Reach,
999 /// focus and the focus ring", for the three terms and who owns each.
1000 ///
1001 /// `#[non_exhaustive]` for the reason [`Fill`] and [`Depth`] carry it: growth
1002 /// must not be a lockstep event across the three renderers.
1003 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1004 #[non_exhaustive]
1005 pub enum State {
1006 /// Present, visible, and not answering.
1007 ///
1008 /// Not the same as absent, and deliberately not a [`Fill`]: a disabled
1009 /// control keeps the surface it always had and stops responding, so what
1010 /// changes is its content and its interactivity rather than what it is.
1011 Disabled,
1012 }
1013
1014 impl State {
1015 /// Whether a region in this state stops answering the pointer.
1016 ///
1017 /// Stated in the description rather than left to each renderer, on the same
1018 /// reasoning as [`Bevel::pressed`]: a cascade carries it for free and an
1019 /// immediate-mode renderer resolves it per call site, so leaving it unsaid
1020 /// means resolving it once per consumer and disagreeing.
1021 #[must_use]
1022 pub const fn suppresses_interaction(self) -> bool {
1023 // A match rather than a bare `true`, so a member added to this
1024 // `#[non_exhaustive]` axis has to answer the question rather than
1025 // inheriting an answer.
1026 match self {
1027 Self::Disabled => true,
1028 }
1029 }
1030 }
1031
1032 impl Intent for State {
1033 fn token(self) -> &'static str {
1034 match self {
1035 // Reusing the muted content intent rather than minting a
1036 // `disabled` colour. Disabled is a reduction and not a status, and
1037 // `makeover-webview`'s progress rules already record the reading
1038 // that `content-muted` is what disabled looks like.
1039 Self::Disabled => "content-muted",
1040 }
1041 }
1042 }
1043
1044 /// What a region is saying, when it is saying something.
1045 ///
1046 /// The one intent family shared by badges, notices and nothing else. Kept
1047 /// separate from [`Fill`] because a surface is where a thing sits and a tone is
1048 /// what it means, and the three apps agree on the four statuses:
1049 /// `info_banner` / `warning_banner` in audiofiles, `.toast-info` /
1050 /// `.toast-success` / `.toast-error` in goingson, `.toast.success` /
1051 /// `.toast.error` in Balanced Breakfast.
1052 ///
1053 /// The per-tag palette (`category-one` through `category-six`) is deliberately
1054 /// not here. Which colour a *particular* tag takes is app domain, and both
1055 /// webview apps already carry it as a `data-color` attribute.
1056 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1057 pub enum Tone {
1058 /// No status.
1059 ///
1060 /// Ordinary content, at full weight. It does not also mean muted: a
1061 /// badge reads quiet because [`Token::Badge`] answers no click, which is
1062 /// the renderer's knowledge and not this axis's. A renderer wanting a
1063 /// muted badge reaches for [`Token::interactive`] itself rather than
1064 /// expecting `Neutral` to have muted it.
1065 Neutral,
1066 /// Something worth knowing and nothing to do about it.
1067 Info,
1068 /// Something finished and it worked.
1069 Success,
1070 /// Something the user should look at before continuing.
1071 Warning,
1072 /// Something broken, or something about to be destroyed.
1073 Danger,
1074 }
1075
1076 impl Intent for Tone {
1077 fn token(self) -> &'static str {
1078 match self {
1079 // Neutral has no status token of its own, so it takes the plain
1080 // content intent. It used to answer `content-muted`, which read
1081 // "no status" as "de-emphasised" and muted every figure value in
1082 // the webview. Muting is a renderer's call about a particular
1083 // token, not something the status axis knows.
1084 Self::Neutral => "content",
1085 Self::Info => "info",
1086 Self::Success => "success",
1087 Self::Warning => "warning",
1088 Self::Danger => "danger",
1089 }
1090 }
1091 }
1092
1093 /// A small labelled thing that sits inside something else.
1094 ///
1095 /// Two members, because the three apps drew three taxonomies and only one line
1096 /// runs through all of them: does it answer a click. audiofiles has
1097 /// `classification_badge` (a label) against `tag_chip`, `tag_chip_removable`
1098 /// and `selectable_tag` (all of which do). Balanced Breakfast has `.tag` and
1099 /// `.badge` against `.tag-chip`. goingson is the one that has to move: its
1100 /// `.tag` and `.badge` are a single CSS rule, so every call site has to be read
1101 /// to decide which of the two it always was.
1102 ///
1103 /// The evidence that a chip is a real concept rather than a badge with a
1104 /// cursor: audiofiles inverts its bevel on press and Balanced Breakfast latches
1105 /// `.tag-chip.active` with the inset bevel. Two independent arrivals at "a chip
1106 /// holds itself down", which is exactly what [`Depth::pressed`] already says.
1107 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1108 pub enum Token {
1109 /// Non-interactive status or count. Answers no click.
1110 Badge,
1111 /// An interactive or removable token. Answers a click, and latches if it
1112 /// stands for a filter that is either on or off.
1113 Chip {
1114 /// Whether it carries its own remove affordance.
1115 removable: bool,
1116 },
1117 }
1118
1119 impl Token {
1120 /// Whether this answers a click.
1121 ///
1122 /// The whole difference between the two members, and the reason a renderer
1123 /// with no hover (a touch surface, a terminal) can still tell them apart.
1124 #[must_use]
1125 pub const fn interactive(self) -> bool {
1126 matches!(self, Self::Chip { .. })
1127 }
1128
1129 /// How it sits, given whether it is currently latched down.
1130 ///
1131 /// A badge is flat: it is a label, and giving it an edge would say it can
1132 /// be pressed. A chip is raised, and inset while latched.
1133 #[must_use]
1134 pub const fn depth(self, latched: bool) -> Depth {
1135 match self {
1136 Self::Badge => Depth::Flat,
1137 Self::Chip { .. } if latched => Depth::Well,
1138 Self::Chip { .. } => Depth::Raised,
1139 }
1140 }
1141 }
1142
1143 /// Something the app is telling the user, unprompted.
1144 ///
1145 /// Two concepts, not one with a placement. They differ in more than where they
1146 /// sit: a toast is transient, stacked and self-dismissing, and a banner is
1147 /// persistent, in flow, one per region, and dismissed by fixing the condition
1148 /// it reports. Folding them into one member with a placement parameter would
1149 /// make lifetime, stacking and dismissal all placement-dependent, which is the
1150 /// description leaking renderer policy.
1151 ///
1152 /// All three apps have banners: `info_banner` and `warning_banner` in
1153 /// audiofiles, five of them in goingson (sync, sync-result, vacation-day,
1154 /// timer-active, past-review), `.update-banner` in Balanced Breakfast. The two
1155 /// webview apps also have toasts. So neither member is speculative, and no app
1156 /// gains a concept it lacks except audiofiles, whose renderer may legitimately
1157 /// decline to draw a toast at all.
1158 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1159 pub enum Notice {
1160 /// Transient, stacked, dismisses itself.
1161 Toast,
1162 /// Persistent, in flow, one per region, dismissed by fixing the cause.
1163 Banner,
1164 }
1165
1166 impl Notice {
1167 /// Whether it goes away on its own.
1168 #[must_use]
1169 pub const fn transient(self) -> bool {
1170 matches!(self, Self::Toast)
1171 }
1172
1173 /// How it sits.
1174 ///
1175 /// A toast floats above the page rather than resting on it, which is
1176 /// [`Fill::Overlay`]'s whole reason to exist. A banner is a card in the
1177 /// flow. Both are raised, and they are raised off different things.
1178 #[must_use]
1179 pub const fn fill(self) -> Fill {
1180 match self {
1181 Self::Toast => Fill::Overlay,
1182 Self::Banner => Fill::Raised,
1183 }
1184 }
1185 }
1186
1187 /// The parts of a list row.
1188 ///
1189 /// Four to begin with, taken from Balanced Breakfast, which was the only
1190 /// consumer that had all of them (`row-primary`, `row-secondary`, `row-meta`,
1191 /// `row-actions`). audiofiles has two and no slot structure at all, so it gains
1192 /// meta and actions as real work rather than a rename; goingson moves off
1193 /// `task-row` / `task-cell`.
1194 ///
1195 /// [`Tokens`](Self::Tokens) joined at 0.9.0, and `#[non_exhaustive]` with it.
1196 /// See the crate header for why the two arrived together.
1197 ///
1198 /// # Meta against Tokens
1199 ///
1200 /// The line is whether the thing has its own standing. `Meta` is one short
1201 /// trailing fact about the row, written as text: a count, a size, a date.
1202 /// `Tokens` is a set of small labelled things, each of which can be toned and
1203 /// can answer a click. "3 files" is meta. A status badge that is amber, and a
1204 /// tag you can click to filter by, are tokens.
1205 ///
1206 /// Keeping them apart is what a single widened slot would have foreclosed. A
1207 /// renderer can right-align one string and cannot usefully do the same to a
1208 /// strip of chips, and a fact that is not clickable should not be drawn as
1209 /// though it were.
1210 /// How much vertical room a part's text may take.
1211 ///
1212 /// A row is an inline run and every part in it is a leaf, so a part's text has
1213 /// always been drawn on one line and no description could say otherwise. Two
1214 /// apps say otherwise in their own stylesheets, both to the same number and
1215 /// both with a comment explaining it: Balanced Breakfast clamps a feed row's
1216 /// title to two lines (`.row--article .row-primary`, whose comment reads
1217 /// "overrides .row-primary's single flex line"), and goingson clamps a
1218 /// problem's body to two ("two lines is enough to recognize one, and the full
1219 /// text is in the task once promoted").
1220 ///
1221 /// Two named tiers rather than a line count, and the count is what the measured
1222 /// demand argues against. Both sites want exactly one tier past the default,
1223 /// and a number invites a row whose primary is a paragraph, which is a block
1224 /// and has no business in a run. A third tier is a decision, made here, rather
1225 /// than something a call site can reach for.
1226 ///
1227 /// What a renderer owes it: `Tight` is what a run already does and needs no
1228 /// answer. `Relaxed` is at most two lines and then truncation, however that
1229 /// renderer truncates -- a webview clamps, a terminal wraps into two rows of
1230 /// cells, an immediate-mode renderer caps the galley. A renderer that cannot
1231 /// give two lines may draw one; what it may not do is grow without bound,
1232 /// because the run is a line and the row's neighbours are relying on that.
1233 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
1234 #[non_exhaustive]
1235 pub enum Flow {
1236 /// One line. What every part did before this type existed.
1237 #[default]
1238 Tight,
1239 /// Up to two lines, then truncated.
1240 Relaxed,
1241 }
1242
1243 impl Flow {
1244 /// How many lines the part may take.
1245 ///
1246 /// A number here rather than in the enum, because a renderer needs one and
1247 /// a call site does not. That asymmetry is the whole argument for the
1248 /// tiers: the description says how much room the thing deserves and this
1249 /// says what that costs, so a third tier changes one line rather than every
1250 /// consumer's arithmetic.
1251 #[must_use]
1252 pub const fn lines(self) -> u8 {
1253 match self {
1254 Self::Relaxed => 2,
1255 // Including any tier added later: one line is the safe reading of
1256 // an unknown flow, since it is what the run guaranteed before flows
1257 // existed.
1258 _ => 1,
1259 }
1260 }
1261 }
1262
1263 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1264 #[non_exhaustive]
1265 pub enum RowPart {
1266 /// The thing itself. What the row is called.
1267 Primary,
1268 /// Supporting text under the primary.
1269 Secondary,
1270 /// A short trailing fact: a count, a size, a date.
1271 Meta,
1272 /// Controls that act on this row.
1273 Actions,
1274 /// Small labelled things belonging to the row: badges, chips, tags.
1275 ///
1276 /// Each carries its own [`Token`] kind and [`Tone`], so a renderer with no
1277 /// colour still has the kind to work with, and one with no chips still has
1278 /// the label. That is the constrained-consumer test this vocabulary exists
1279 /// to pass, and it is why the tone lives on the token rather than on the
1280 /// part.
1281 Tokens,
1282 /// How much of a set the row's thing has done: a [`Meter`] in the row.
1283 ///
1284 /// Added 0.11.0, `da5666ae`, and it is [`Tokens`](Self::Tokens)'s problem
1285 /// again with a different payload. [`Meter`] arrived at 0.10.0 and closed
1286 /// two of the seven sites that asked for it; the other five sit in rows, and
1287 /// a row holds no nodes by the ruling that a row part may not carry an
1288 /// arbitrary node — the door through which a description becomes a
1289 /// templating language. So the part carries the *description of a bar*
1290 /// rather than a node, exactly as `Tokens` carries tags rather than nodes.
1291 ///
1292 /// Without it a row flattens the proportion into [`Meta`](Self::Meta) as
1293 /// "3/7 subtasks", which keeps both numbers and loses the reading, the same
1294 /// way a toned status badge read as prose before `Tokens`.
1295 Proportion,
1296 }
1297
1298 impl RowPart {
1299 /// What the part is worth when the run does not fit.
1300 ///
1301 /// The default only. A part may say otherwise, and a renderer reads the
1302 /// part rather than the role; this is what a description that has never
1303 /// heard of [`Priority`] means, which is every description written before
1304 /// the field existed.
1305 ///
1306 /// Deriving it from the role is the thing this vocabulary has otherwise
1307 /// been moving away from, and it is right here for one reason: the roles
1308 /// already encode this ranking and every consumer already assumes it.
1309 /// [`Primary`](Self::Primary) is what the row is called, and
1310 /// [`Priority::Essential`]'s own doc was written about exactly that --
1311 /// "without it the row does not identify itself".
1312 ///
1313 /// [`Actions`](Self::Actions) is `Essential` and it is the interesting one.
1314 /// A control is not a fact, so dropping it does not cost the reader a
1315 /// detail; it costs them the only way to act on the row, and in a terminal
1316 /// it silently removes something focus had already been claimed for. A
1317 /// renderer that needs room takes it from what the row *says*, never from
1318 /// what it *offers*.
1319 ///
1320 /// An unknown member reads as [`Priority::Secondary`]: droppable, but not
1321 /// first, since guessing `Optional` for something this crate has not been
1322 /// taught would make a new member the first thing to vanish.
1323 #[must_use]
1324 pub const fn priority(self) -> Priority {
1325 match self {
1326 Self::Primary | Self::Actions => Priority::Essential,
1327 Self::Meta | Self::Proportion => Priority::Optional,
1328 _ => Priority::Secondary,
1329 }
1330 }
1331
1332 /// The content intent the part takes.
1333 #[must_use]
1334 pub const fn intent(self) -> &'static str {
1335 match self {
1336 Self::Primary => "content",
1337 Self::Secondary => "content-secondary",
1338 Self::Meta => "content-muted",
1339 // Actions carry controls rather than text, so they inherit.
1340 Self::Actions => "content",
1341 // So do tokens: each one carries its own tone, and a part-level
1342 // intent underneath it would fight the token that sits on it.
1343 Self::Tokens => "content",
1344 // And so does a proportion, for the same reason: the meter carries
1345 // the tone, and it is about the ratio rather than about the row.
1346 Self::Proportion => "content",
1347 }
1348 }
1349 }
1350
1351 /// How far down the heading tree a title sits.
1352 ///
1353 /// Three, and only the three that are actually headings. The bands those used
1354 /// to be filed with (goingson's `.page-header`, Balanced Breakfast's `.header`
1355 /// and `.detail-header`) are arrangement, not type, and live at
1356 /// [`Region::Band`]. One of them contains no text at all.
1357 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1358 pub enum Heading {
1359 /// Names the whole screen. One per screen.
1360 Page,
1361 /// Names a block within the screen.
1362 Section,
1363 /// Names a sub-block inside an already-named section.
1364 Subsection,
1365 }
1366
1367 impl Heading {
1368 /// Whether a rule follows the heading.
1369 ///
1370 /// audiofiles' `section_header` draws a separator and its
1371 /// `subsection_label` deliberately does not, which is the only thing
1372 /// distinguishing the two once weight and colour are deferred.
1373 #[must_use]
1374 pub const fn separated(self) -> bool {
1375 matches!(self, Self::Section)
1376 }
1377 }
1378
1379 /// A control that picks between things.
1380 ///
1381 /// Three, because three distinct behaviours are in play and collapsing any two
1382 /// loses something. A segmented control picks a value; a tab picks a pane; a
1383 /// toggle picks nothing and simply holds itself on or off.
1384 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1385 pub enum Selector {
1386 /// Exactly one of N, and the options abut.
1387 Segmented,
1388 /// Independent on or off, on its own.
1389 Toggle,
1390 /// Navigation between panes. The folder semantic.
1391 Tabs,
1392 }
1393
1394 impl Selector {
1395 /// How the chosen option sits.
1396 ///
1397 /// Held in for a segmented control and a toggle, which is the same shape
1398 /// pressing produces and the whole economy of the idiom: one appearance,
1399 /// two reasons to wear it. A tab is the exception, because the selected
1400 /// folder tab comes *forward* to join the pane it opens.
1401 #[must_use]
1402 pub const fn chosen(self) -> Depth {
1403 match self {
1404 Self::Segmented | Self::Toggle => Depth::Well,
1405 Self::Tabs => Depth::Raised,
1406 }
1407 }
1408
1409 /// How the options that were *not* picked sit.
1410 ///
1411 /// Added 0.3.0. Describing only [`Selector::chosen`] left the unchosen
1412 /// option falling through to [`Depth::Flat`], which says it is level with
1413 /// the strip it sits in, and no renderer emitted anything for it. That is
1414 /// wrong in both directions and goingson proved it: its unchosen tabs are
1415 /// recessed by hand, and being recessed is *why* the chosen one reads as
1416 /// coming forward. Against a flat strip, a raised chosen tab is a bevel
1417 /// drawn on the strip's own colour, which is a much weaker folder effect
1418 /// than the contrast the idiom is named after.
1419 ///
1420 /// Each member is the inverse of its chosen state, which is the whole
1421 /// content of "picked" once colour is deferred:
1422 ///
1423 /// - Tabs recede, so the chosen one comes forward.
1424 /// - A segment and a toggle stand up, so the chosen one is held in.
1425 #[must_use]
1426 pub const fn unchosen(self) -> Depth {
1427 match self {
1428 Self::Tabs => Depth::Sunken,
1429 Self::Segmented | Self::Toggle => Depth::Raised,
1430 }
1431 }
1432
1433 /// Whether the options touch.
1434 ///
1435 /// The gap is the entire difference between a segmented control and a row
1436 /// of buttons that happen to sit near each other, which is what audiofiles'
1437 /// `segmented_control` says in its own comment and why it zeroes the
1438 /// spacing by hand.
1439 #[must_use]
1440 pub const fn abutting(self) -> bool {
1441 matches!(self, Self::Segmented | Self::Tabs)
1442 }
1443 }
1444
1445 /// What is in a region right now.
1446 ///
1447 /// The state, not the shimmer. Whether pending paints a skeleton, a spinner or
1448 /// nothing at all is renderer policy, the same class of decision that got
1449 /// `Fill::fallback` deleted from this crate. goingson and Balanced Breakfast
1450 /// each grew a skeleton with differently-named parts; both keep them, as the
1451 /// webview renderer's expression of [`Readiness::Pending`]. audiofiles has none
1452 /// and needs none, because an immediate-mode renderer simply repaints.
1453 ///
1454 /// # Four states and not two, as of 0.12.0
1455 ///
1456 /// `703f4cd2`. It named `Ready` and `Pending` and stopped, so a described screen
1457 /// whose list came back empty had to render an empty region or invent its own
1458 /// placeholder text, and neither says what it is. goingson draws one at 27 sites
1459 /// across 12 files and Balanced Breakfast at 9, with a class family that had
1460 /// already drifted into `empty-state`, `empty-state--error`, `error-state` and
1461 /// six more.
1462 ///
1463 /// The four are one axis because they are mutually exclusive: a region shows its
1464 /// content, or a sign that it is coming, or a sign that there is none, or a sign
1465 /// that it broke. Never two. That is the test for one enum against several
1466 /// fields, and it is why this grew rather than a new member arriving beside it.
1467 ///
1468 /// # What is not here
1469 ///
1470 /// **The message.** "No projects yet" is content, and this names a state. It
1471 /// lives with whatever holds the region — in quasi's case a `Slot` — alongside
1472 /// the action that leads out of the emptiness, since an address is the one thing
1473 /// this crate never names.
1474 ///
1475 /// **How much room it gets.** goingson's `--compact`, `--dashboard` and
1476 /// `--padded` are the same state at three sizes, and a size is
1477 /// `makeover-geometry`'s question. Naming them here would be this crate stating
1478 /// values again.
1479 ///
1480 /// **The icon.** Presentation, and each host has its own answer or none.
1481 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1482 #[non_exhaustive]
1483 pub enum Readiness {
1484 /// The content is here.
1485 Ready,
1486 /// The content is on its way.
1487 ///
1488 /// For a region that changes *after* the first paint, and never for the
1489 /// first paint itself: see "First paint is final paint" in the crate header.
1490 /// A host that renders once, with its data already in hand, has nothing to
1491 /// say this about, and a screen arriving in this state is describing a
1492 /// moment its host should not have been in.
1493 ///
1494 /// What stands in occupies the geometry the content will occupy. A stand-in
1495 /// sized to itself rather than to what replaces it is the reflow the rule
1496 /// forbids, arriving one repaint later.
1497 Pending,
1498 /// The content arrived and there is none of it.
1499 ///
1500 /// Not a failure. An empty list is the normal state of a new install, and a
1501 /// renderer that drew it in a danger tone would be reporting a fault where
1502 /// there is none.
1503 Empty,
1504 /// The content did not arrive.
1505 Failed,
1506 }
1507
1508 impl Readiness {
1509 /// Whether the region draws its own content, or something standing in for
1510 /// it.
1511 ///
1512 /// The question every renderer asks first, so it is answered once here
1513 /// rather than by a `matches!` in each. A state added later is a stand-in
1514 /// until proven otherwise: falling back to drawing content that may not be
1515 /// there is the worse of the two mistakes.
1516 #[must_use]
1517 pub const fn shows_content(self) -> bool {
1518 matches!(self, Self::Ready)
1519 }
1520
1521 /// What the state means, for a renderer choosing a colour.
1522 ///
1523 /// Derived rather than carried, which is the opposite of [`Meter`] and
1524 /// [`Figure`], and the difference is worth stating: a proportion's meaning
1525 /// depends on what is being counted and only the app knows it, while
1526 /// "nothing here yet" and "this broke" mean the same thing in every app that
1527 /// will ever have them.
1528 #[must_use]
1529 pub const fn tone(self) -> Tone {
1530 match self {
1531 Self::Failed => Tone::Danger,
1532 _ => Tone::Neutral,
1533 }
1534 }
1535 }
1536
1537 /// An action is waiting on something that resolves once, in expected finite
1538 /// time.
1539 ///
1540 /// The control-side sibling of [`Readiness`]. That enum names four states for a
1541 /// region and named nothing at all for the button that is currently doing what
1542 /// it was clicked for, so the in-flight treatment is hand-written wherever it
1543 /// exists: the MNW server carries 57 in-flight indicators against 2 guards
1544 /// against a second press, which is the spinner mostly present and the guard
1545 /// mostly absent, on a codebase whose money path is a purchase button.
1546 ///
1547 /// # What is described here, and what is not
1548 ///
1549 /// The fact is that there is an outstanding thing which will complete. Not that
1550 /// the address is remote: a heavy local query waits too, and a server calling a
1551 /// payment provider is not the browser leaving the app. Not that the call is
1552 /// slow either, which is a judgement about a call rather than a property of one.
1553 ///
1554 /// Resolving **once** is the boundary, and it is what separates this from a
1555 /// screen that keeps changing. A live screen never resolves and has no name in
1556 /// this crate yet.
1557 ///
1558 /// # One mark, two renderings
1559 ///
1560 /// | what reads it | what it does |
1561 /// |---|---|
1562 /// | a control that was pressed | goes busy and refuses a second press until it resolves |
1563 /// | a region fed by it | stands in as [`Readiness::Pending`], then fills |
1564 ///
1565 /// The two were on the table separately and both were taken. Controls alone
1566 /// leaves a slow region hand-split into its own route, which is what MNW's user
1567 /// dashboard does with its payout summary; regions alone leaves the purchase
1568 /// button unguarded.
1569 ///
1570 /// # A quantity when it is measured, never a duration
1571 ///
1572 /// [`amount`](Self::amount) is stated only when it is a measured fact about the
1573 /// payload. An upload's file length, yes; a round trip to a payment provider,
1574 /// [`None`]. A duration is described nowhere, and a renderer may not manufacture
1575 /// one from the amount either: a determinate bar shows what is done over what
1576 /// there is, plus the time it has taken so far, and never a remaining time, an
1577 /// arrival time or a rate extrapolated forwards. A prediction is wrong the
1578 /// moment the transfer stalls, and being confidently wrong is worse than being
1579 /// honestly indeterminate.
1580 ///
1581 /// This is why the crate refuses to say how long an undo stays offered and
1582 /// accepts a byte count here. The refusal is about naming a decision that
1583 /// belongs to the renderer; a file's length is not a decision, nobody chose it.
1584 ///
1585 /// # Not [`Meter`]
1586 ///
1587 /// [`Meter`] is how much of a set is done, and its own docs refuse the progress
1588 /// of an operation on the grounds that a description is built once and dropped
1589 /// while an operation runs between renders. That refusal stands. This names the
1590 /// operation and its size, which is all that is known before it starts; how much
1591 /// of it has gone through is the renderer's to observe live, and nothing round
1592 /// trips through a description to say so.
1593 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
1594 #[non_exhaustive]
1595 pub struct Awaiting {
1596 /// Total work to get through, when it is a measured fact about the payload.
1597 ///
1598 /// `None` when the wait has no countable size, which is the common case and
1599 /// the default.
1600 ///
1601 /// Unit-agnostic on purpose. Bytes for an upload, rows for an import; what
1602 /// is being counted is the app's business and a renderer draws a proportion
1603 /// either way.
1604 pub amount: Option<u64>,
1605 }
1606
1607 impl Awaiting {
1608 /// A wait with no countable size.
1609 #[must_use]
1610 pub const fn unmeasured() -> Self {
1611 Self { amount: None }
1612 }
1613
1614 /// A wait whose size is known.
1615 ///
1616 /// Reach for it only with a measured figure. An estimate written in here is
1617 /// a prediction wearing a fact's clothes, and the renderer has no way to
1618 /// tell the two apart.
1619 #[must_use]
1620 pub const fn of(amount: u64) -> Self {
1621 Self {
1622 amount: Some(amount),
1623 }
1624 }
1625
1626 /// Whether there is a proportion to draw.
1627 ///
1628 /// The question every renderer asks first, answered once here rather than by
1629 /// a `matches!` in each. False means indeterminate, which is the honest
1630 /// drawing when nothing countable was measured.
1631 #[must_use]
1632 pub const fn is_determinate(self) -> bool {
1633 self.amount.is_some()
1634 }
1635 }
1636
1637 /// How much of a set is done.
1638 ///
1639 /// Added 0.10.0. Nine sites across the two webview apps drew a bar and nothing
1640 /// here named one, so every described screen concatenated the two numbers into
1641 /// its heading text instead: "Subtasks 3/7", "Time Tracking 45m tracked / 30m
1642 /// est, over". Every fact survives that and the reading does not, which is the
1643 /// same loss `RowPart::Tokens` closed when a toned status badge became prose.
1644 ///
1645 /// # Why a pair and not a percentage
1646 ///
1647 /// Both numbers, not the percentage the apps compute from them. The percentage
1648 /// was the obvious shape and it had already been tried: goingson's
1649 /// `Task::time_progress` divides, rounds, and then clamps to 100, which throws
1650 /// away the one case the bar exists to show — 45 minutes tracked against a
1651 /// 30-minute estimate. It carries a separate `is_over_estimate` boolean beside
1652 /// it to recover the fact the clamp dropped. A pair keeps the over-run without a
1653 /// companion flag, and [`percent`](Meter::percent) is still one call away for a
1654 /// renderer that wants it.
1655 ///
1656 /// The pair is also what the apps already have at every site. All seven
1657 /// determinate bars write the ratio into the accessible layer and never the
1658 /// percentage: `title="3/7 subtasks"`, `aria-label="3 of 7 subtasks completed"`,
1659 /// a milestone's own `3/7` span. Given 43 nothing can recover "3 of 7", so a
1660 /// percentage member would have made [`label`](Meter::label) mandatory at every
1661 /// call site, which is the concatenated text this member removes, moved one
1662 /// layer down.
1663 ///
1664 /// # What this is not
1665 ///
1666 /// The progress of an *operation*. Two of the nine sites are that — goingson's
1667 /// focus timer, Balanced Breakfast's feed fetch — and they get nothing here, on
1668 /// purpose. Both are imperative controllers over a live handle, driven by a tick
1669 /// or an event stream, and a description is built once and dropped. Holding one
1670 /// would mean growing a way to update a description between renders, which is a
1671 /// different feature. [`Readiness::Pending`] and a [`Notice::Toast`] carry the
1672 /// honest part.
1673 ///
1674 /// The two cases are distinguishable in the markup rather than by taste: every
1675 /// determinate bar in both apps carries a tone, and neither operation bar
1676 /// carries one. Two codebases drew that line the same way without coordinating.
1677 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1678 pub struct Meter<'a> {
1679 /// How much is done. May exceed [`total`](Self::total), and that is the
1680 /// case worth drawing.
1681 pub done: u32,
1682 /// How much there is to do. Zero means there is no set, not that the set is
1683 /// complete.
1684 pub total: u32,
1685 /// What the proportion means right now.
1686 ///
1687 /// Carried rather than derived, because no renderer can work it out. The
1688 /// same 90% is [`Tone::Success`] on a subtask rollup and [`Tone::Danger`] on
1689 /// a time estimate, and goingson picks between them from `is_over_estimate`,
1690 /// a fact about the data and not about the number.
1691 pub tone: Tone,
1692 /// What is being counted, if the bar says so: "subtasks", "tasks".
1693 ///
1694 /// The noun, not the ratio. A renderer builds "3 of 7 subtasks" from this
1695 /// and the two numbers; handing it the assembled string would put the
1696 /// sentence order in the description, where a terminal at one line and a
1697 /// tooltip want different ones.
1698 pub label: Option<&'a str>,
1699 }
1700
1701 impl<'a> Meter<'a> {
1702 /// A proportion with no tone and no label.
1703 #[must_use]
1704 pub const fn new(done: u32, total: u32) -> Self {
1705 Self {
1706 done,
1707 total,
1708 tone: Tone::Neutral,
1709 label: None,
1710 }
1711 }
1712
1713 /// What the proportion means.
1714 #[must_use]
1715 pub const fn tone(mut self, tone: Tone) -> Self {
1716 self.tone = tone;
1717 self
1718 }
1719
1720 /// What is being counted.
1721 #[must_use]
1722 pub const fn label(mut self, label: &'a str) -> Self {
1723 self.label = Some(label);
1724 self
1725 }
1726
1727 /// How full the bar is, 0 to 100, clamped.
1728 ///
1729 /// For drawing, which is the only thing a clamped number is good for. Ask
1730 /// [`overflowing`](Self::overflowing) before reporting it as a fact, or this
1731 /// is `time_progress`'s bug again with the clamp moved.
1732 ///
1733 /// An empty set reads as 0. Nothing is done, because there is nothing to do
1734 /// and no bar to fill; the apps guard on the count before drawing at all.
1735 #[must_use]
1736 pub const fn percent(&self) -> u8 {
1737 if self.total == 0 {
1738 return 0;
1739 }
1740 let scaled = (self.done as u64 * 100) / self.total as u64;
1741 if scaled > 100 { 100 } else { scaled as u8 }
1742 }
1743
1744 /// Whether more is done than there was to do.
1745 ///
1746 /// The fact [`percent`](Self::percent) destroys, kept reachable so a
1747 /// renderer can mark the over-run rather than drawing a full bar and
1748 /// implying it landed exactly.
1749 #[must_use]
1750 pub const fn overflowing(&self) -> bool {
1751 self.done > self.total
1752 }
1753
1754 /// Whether there is a set at all.
1755 ///
1756 /// A meter over nothing is sayable on purpose, for the same reason a field
1757 /// with no options is: it is what an app with an unloaded count actually
1758 /// has, and a renderer that shows an empty bar says so on screen rather than
1759 /// dividing by zero.
1760 #[must_use]
1761 pub const fn is_empty(&self) -> bool {
1762 self.total == 0
1763 }
1764 }
1765
1766 /// One figure with a caption: a number and what it counts.
1767 ///
1768 /// The dashboard shape. A large value over a small caption, several of them in a
1769 /// strip: a current streak, a completion rate, a total. Added 0.11.0,
1770 /// `93c6a174`, after goingson turned out to have five of them across five
1771 /// screens with five class vocabularies for the one shape — `task-overview-stat`,
1772 /// `stat-box`, `month-stat-item`, `contact-summary-stat`, `sync-stat`. Four put
1773 /// the value above the caption and one inverts it, which is drift inside the
1774 /// shape rather than a second shape.
1775 ///
1776 /// # Why the value is text
1777 ///
1778 /// "17", "84%", "12/30", "3d". A figure is whatever the app computed, already
1779 /// formatted, and the formatting is the app's because only it knows whether the
1780 /// number is a percentage, a duration or a ratio. This carries none of the
1781 /// arithmetic [`Meter`] carries, and that is the difference between them: a
1782 /// meter is a proportion a renderer draws, and a figure is a fact a renderer
1783 /// sets in type.
1784 ///
1785 /// # Tone is carried, for [`Meter`]'s reason
1786 ///
1787 /// Three of the five sites tone the figure by their own means — `red`/`blue` on
1788 /// the weekly review, a `${type}` class on the monthly one, `sync-stat-warn` on
1789 /// sync. So tone is carried at every site that needs it and derived at none, and
1790 /// no renderer can work out that a streak of zero is worth colouring.
1791 ///
1792 /// # What is not here
1793 ///
1794 /// Whether the figure answers a click. One of the five is a control — sync's
1795 /// "Not Applied: 3" opens the list — and an action is not something this crate
1796 /// can name: nothing here knows what a route is. That belongs beside the figure
1797 /// in whatever layer holds the actions, the same way a row's activation sits
1798 /// beside its parts rather than inside them.
1799 ///
1800 /// The arrangement is not here either. Several figures in a strip is a set, and
1801 /// a renderer given them one at a time cannot tell it is looking at one; the
1802 /// layer that holds the tree is where the set gets said.
1803 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1804 pub struct Figure<'a> {
1805 /// The number, formatted the way the app means it to read.
1806 pub value: &'a str,
1807 /// What it counts. The caption under the value.
1808 pub caption: &'a str,
1809 /// How the value has moved, if the app is tracking that.
1810 ///
1811 /// Added 0.13.0. Text, for [`value`](Self::value)'s reason: only the app
1812 /// knows whether a move reads as `+12.5%`, `+3` or `2x`, and a renderer
1813 /// handed a number would have to guess.
1814 ///
1815 /// This is what [`tone`](Self::tone) was for and had no consumer of. The MNW
1816 /// server has four screens whose stat card is a label, a value and a delta,
1817 /// and the delta is the toned part: the figure itself is an ordinary fact
1818 /// and it is the movement that reads as good or bad. Without this the delta
1819 /// has to be folded into the caption, which loses the tone and reads as a
1820 /// longer caption rather than as a second, smaller line.
1821 pub change: Option<&'a str>,
1822 /// What the figure means right now. [`Tone::Neutral`] is an ordinary fact.
1823 ///
1824 /// Applies to [`change`](Self::change) where there is one, since that is the
1825 /// part that carries the judgement, and to the value where there is not.
1826 pub tone: Tone,
1827 }
1828
1829 impl<'a> Figure<'a> {
1830 /// A figure that is an ordinary fact.
1831 #[must_use]
1832 pub const fn new(value: &'a str, caption: &'a str) -> Self {
1833 Self {
1834 value,
1835 caption,
1836 change: None,
1837 tone: Tone::Neutral,
1838 }
1839 }
1840
1841 /// How the value has moved.
1842 #[must_use]
1843 pub const fn change(mut self, change: &'a str) -> Self {
1844 self.change = Some(change);
1845 self
1846 }
1847
1848 /// What the figure means.
1849 #[must_use]
1850 pub const fn tone(mut self, tone: Tone) -> Self {
1851 self.tone = tone;
1852 self
1853 }
1854 }
1855
1856 /// Something the user can do, and what it costs to say so.
1857 ///
1858 /// Added 0.17.0, out of `quasi-tui`: the terminal renderer had drawn one of
1859 /// these for months and every other consumer that wanted a button had written
1860 /// its own, because this layer named [`RowPart::Actions`] as a *slot* and never
1861 /// named the thing that goes in it. Beside [`Meter`] and [`Figure`] for the
1862 /// reason those are here: a renderer that is handed the parts has to decide how
1863 /// to say them, and a renderer that is handed a finished string has already had
1864 /// the decision made for it.
1865 ///
1866 /// No address. Where a control goes is the app's business and every host
1867 /// follows it differently — an `hx-get`, a protocol URL, a function call — so
1868 /// the description says what the control *is* and the caller keeps what it
1869 /// does. That is the same split [`Choice`] makes.
1870 ///
1871 /// No confirmation flag either, and that one is a finding rather than an
1872 /// omission: a question asked *after* a control is pressed belongs to whatever
1873 /// is holding the interaction, and a renderer that drew it would be asking
1874 /// before there was anything to answer.
1875 /// How a picture sits in the box it is given.
1876 ///
1877 /// An intent rather than a value, so a renderer picks the expression it has:
1878 /// `object-fit` in a webview, a texture's UV rect in egui, and in a terminal a
1879 /// choice about how many cells the blit gets. Named because MNW already makes
1880 /// the distinction deliberately at 17 sites and makes it three different ways,
1881 /// which is a policy the app decided rather than one a shared crate would be
1882 /// picking by accident.
1883 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
1884 #[non_exhaustive]
1885 pub enum Fit {
1886 /// The picture's own proportions, and the box takes the height they imply.
1887 ///
1888 /// The default because it is the only one that shows the whole picture at
1889 /// its own shape, so a renderer that ignores this enum entirely is still
1890 /// right about the common case. A screenshot wants this; the shipped MNW
1891 /// carousel sets no `object-fit` at all, which is this.
1892 #[default]
1893 Natural,
1894 /// Fill the box and crop whatever does not fit.
1895 ///
1896 /// For a picture in a slot whose shape the layout fixed: a thumbnail, an
1897 /// avatar, cover art. 15 of MNW's 17 sites.
1898 Cover,
1899 /// Fit inside the box whole, leaving space on two sides.
1900 ///
1901 /// The letterbox. For when the whole picture matters more than filling the
1902 /// space, and the space is not the picture's shape.
1903 Contain,
1904 }
1905
1906 /// A picture, and what it says to someone who is not looking at it.
1907 ///
1908 /// # No source
1909 ///
1910 /// [`Act`]'s split, for [`Act`]'s reason. A source is an address, and this
1911 /// crate has no notion of an address: it says what a thing *is* and the caller
1912 /// keeps what it points at. The three findings dropped from 0.11.0 were all
1913 /// this same shape.
1914 ///
1915 /// It matters more here than it does for a control, because a picture is the
1916 /// one member where the address is most of what a webview needs and *none* of
1917 /// what the description knows. `quasi_router::Node::Image` carries the URL, the
1918 /// way it carries an `Action` for a control.
1919 ///
1920 /// # Why [`alt`](Self::alt) is not optional
1921 ///
1922 /// Every other host has to draw something, and for two of the three the alt
1923 /// text is not a fallback but the whole rendering: a terminal without a
1924 /// graphics protocol has the words and nothing else. Making it optional would
1925 /// make "this picture is invisible on a terminal" the default, and the
1926 /// description would be carrying a webview assumption in its shape.
1927 ///
1928 /// An image that genuinely says nothing — a rule, a spacer, a decoration
1929 /// repeating what the text beside it already said — is an empty `alt`, which is
1930 /// the same thing HTML means by it and is a claim rather than an oversight.
1931 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1932 pub struct Image<'a> {
1933 /// What the picture says, for anything not showing it.
1934 ///
1935 /// Empty means the picture is decorative and adds nothing to the text
1936 /// around it. See the type's own docs on why this is not an `Option`.
1937 pub alt: &'a str,
1938 /// A visible line under the picture, where the app wants one.
1939 ///
1940 /// Distinct from [`alt`](Self::alt) and the difference is who it is for: a
1941 /// caption is content everybody reads, alt text is what stands in for the
1942 /// picture. A screenshot captioned "The library view" still needs alt text
1943 /// describing what is in the shot.
1944 pub caption: Option<&'a str>,
1945 /// How it sits in the box it is given.
1946 pub fit: Fit,
1947 /// The picture's own dimensions, where the app knows them.
1948 ///
1949 /// **Not a display size**, and that distinction is what makes this belong
1950 /// here rather than fall foul of the deferral rule. Saying a picture should
1951 /// be 320 points wide is a layout value and is not the description's to
1952 /// give. Saying the file is 5120x3412 is a fact *about the picture*, the
1953 /// same kind of fact [`alt`](Self::alt) is, and no renderer can find it out
1954 /// without fetching the bytes.
1955 ///
1956 /// # What it is for, and it is not decoration
1957 ///
1958 /// Without it a renderer cannot reserve room, so the picture occupies
1959 /// nothing until it arrives and then takes its full height at once,
1960 /// shoving everything below it down the screen. Measured on MNW's landing
1961 /// page 2026-08-14: a 478px jump per frame, and a cumulative layout shift
1962 /// of 0.087 for the page, which is most of the way to the 0.1 that counts
1963 /// as bad.
1964 ///
1965 /// Every host wants it and none can derive it. A webview writes `width` and
1966 /// `height` so the browser holds the space; egui sizes a texture; a
1967 /// terminal with a graphics protocol scales a blit into cells. This was
1968 /// missing from 0.21.0, which is the release that added [`Image`], and its
1969 /// absence is the defect rather than an omission.
1970 ///
1971 /// `None` is honest and common: a creator-uploaded image whose dimensions
1972 /// the app never recorded genuinely does not know. It means the renderer
1973 /// cannot reserve, not that the picture has no size.
1974 pub intrinsic: Option<Extent>,
1975 /// Whether the picture is needed with the screen, or can arrive later.
1976 pub loading: Loading,
1977 }
1978
1979 /// A picture's own pixel dimensions.
1980 ///
1981 /// Deliberately not [`makeover_geometry`]'s business. Geometry answers *how
1982 /// much space a thing should get*, which is a scale question with the same
1983 /// answer on every screen. This is the intrinsic size of one asset, which is a
1984 /// fact about that asset and varies per picture.
1985 ///
1986 /// [`makeover_geometry`]: https://docs.rs/makeover-geometry
1987 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1988 pub struct Extent {
1989 /// Width in the picture's own pixels.
1990 pub width: u32,
1991 /// Height in the picture's own pixels.
1992 pub height: u32,
1993 }
1994
1995 impl Extent {
1996 /// A picture's dimensions.
1997 #[must_use]
1998 pub const fn new(width: u32, height: u32) -> Self {
1999 Self { width, height }
2000 }
2001
2002 /// Width over height, or `None` if either side is zero.
2003 ///
2004 /// The form a renderer actually reserves space with: a box that knows its
2005 /// proportion holds the right height at any width, which is what a
2006 /// responsive picture needs and what a fixed pixel height cannot give.
2007 #[must_use]
2008 pub fn ratio(self) -> Option<f32> {
2009 (self.width > 0 && self.height > 0).then(|| self.width as f32 / self.height as f32)
2010 }
2011 }
2012
2013 /// When a picture is needed.
2014 ///
2015 /// A claim about *importance and position* rather than a fetch mechanism, which
2016 /// is why it is the description's to make: only the app knows whether a picture
2017 /// is the first thing on the screen or the fortieth thing down a list.
2018 ///
2019 /// # Eager is the default, and that is a correctness choice
2020 ///
2021 /// 0.21.0 emitted the webview's `loading="lazy"` for every picture, on the
2022 /// evidence that the one consumer measured wrote it. That was reading a habit
2023 /// as a rule. Deferring a picture that is on screen at first paint does not
2024 /// save anything -- it is needed immediately either way -- and it delays the
2025 /// arrival, so the space it eventually takes is claimed later and the shift is
2026 /// more visible, not less.
2027 ///
2028 /// So the safe answer is the default and the optimisation is opted into. A
2029 /// carousel is the case that proves the two cannot be one setting for the
2030 /// renderer to choose: its first frame is on screen and its other frames are
2031 /// not, in the same widget, at the same moment.
2032 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
2033 #[non_exhaustive]
2034 pub enum Loading {
2035 /// Needed with the screen. Fetch it now.
2036 #[default]
2037 Eager,
2038 /// Not on screen yet. It can wait until it is near.
2039 Lazy,
2040 }
2041
2042 impl<'a> Image<'a> {
2043 /// A picture that carries its own proportions.
2044 #[must_use]
2045 pub const fn new(alt: &'a str) -> Self {
2046 Self {
2047 alt,
2048 caption: None,
2049 fit: Fit::Natural,
2050 intrinsic: None,
2051 loading: Loading::Eager,
2052 }
2053 }
2054
2055 /// The picture's own dimensions, so a renderer can hold its place.
2056 #[must_use]
2057 pub const fn intrinsic(mut self, width: u32, height: u32) -> Self {
2058 self.intrinsic = Some(Extent::new(width, height));
2059 self
2060 }
2061
2062 /// This picture is not on screen yet; it can arrive when it is near.
2063 #[must_use]
2064 pub const fn lazy(mut self) -> Self {
2065 self.loading = Loading::Lazy;
2066 self
2067 }
2068
2069 /// A visible line under it.
2070 #[must_use]
2071 pub const fn caption(mut self, caption: &'a str) -> Self {
2072 self.caption = Some(caption);
2073 self
2074 }
2075
2076 /// How it sits in its box.
2077 #[must_use]
2078 pub const fn fit(mut self, fit: Fit) -> Self {
2079 self.fit = fit;
2080 self
2081 }
2082
2083 /// Whether the picture adds anything for someone not looking at it.
2084 ///
2085 /// A renderer with no way to show a picture uses this to decide between
2086 /// drawing the alt text and drawing nothing at all. Both are correct and
2087 /// the difference is this flag: standing in for a decorative rule with the
2088 /// word "decoration" is worse than leaving the space empty.
2089 #[must_use]
2090 pub const fn speaks(self) -> bool {
2091 !self.alt.is_empty()
2092 }
2093 }
2094
2095 /// What a [`Track`]'s integers count.
2096 ///
2097 /// `Track::fraction` never needed this -- the arithmetic is the same whatever
2098 /// the numbers mean -- which is exactly how the ruler came to assume minutes
2099 /// and print `00:00` over a month. A renderer drawing an axis has to write a
2100 /// label, and it cannot derive the unit from the numbers.
2101 ///
2102 /// Added 2026-08-15, after a probe put a fifteen-day span on a
2103 /// thirty-one-slot track and got correct geometry under a wall clock.
2104 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
2105 #[non_exhaustive]
2106 pub enum Unit {
2107 /// Minutes from the start of a day. A day view.
2108 #[default]
2109 Minutes,
2110 /// Whole days. A month strip, a sprint, a stretch of leave.
2111 ///
2112 /// A day-granularity axis is a *strip*, not a calendar: one line with
2113 /// spans laid along it. What it deliberately does not do is wrap into
2114 /// weeks, which is the shape that makes weekday periodicity visible and
2115 /// the one job of a month grid that a strip cannot take over. See the
2116 /// crate header.
2117 Days,
2118 }
2119
2120 /// A window on an axis, in whatever [`Unit`] its [`Track`] counts.
2121 ///
2122 /// The axis a [`Track`] draws. Offsets rather than instants, because a
2123 /// description carrying a `DateTime` would carry a timezone with it and the
2124 /// vocabulary has no business holding one. The app knows which day or month
2125 /// this is; the description says how far along it a thing sits.
2126 ///
2127 /// `to` is exclusive and may exceed the natural period, which is how a span
2128 /// running past the end is said without a second date: under
2129 /// [`Unit::Minutes`], `Span::new(1320, 1560)` is 22:00 to 02:00.
2130 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2131 pub struct Span {
2132 from: u16,
2133 to: u16,
2134 }
2135
2136 impl Span {
2137 /// Midnight to midnight, the ordinary day.
2138 pub const DAY: Self = Self { from: 0, to: 1440 };
2139
2140 /// A span, clamped to a sane one.
2141 ///
2142 /// An empty or backwards span is a caller bug that should not cost a
2143 /// renderer a division by zero, so `to` is forced at least one minute past
2144 /// `from` rather than returning an error nobody can act on. Same reasoning
2145 /// as [`Share::percent`], which clamps rather than refuses.
2146 #[must_use]
2147 pub const fn new(from: u16, to: u16) -> Self {
2148 Self {
2149 from,
2150 to: if to > from { to } else { from + 1 },
2151 }
2152 }
2153
2154 /// The first minute on the axis.
2155 #[must_use]
2156 pub const fn from(self) -> u16 {
2157 self.from
2158 }
2159
2160 /// One past the last minute on the axis.
2161 #[must_use]
2162 pub const fn to(self) -> u16 {
2163 self.to
2164 }
2165
2166 /// How much the axis covers, in its track's unit. Never zero.
2167 #[must_use]
2168 pub const fn length(self) -> u16 {
2169 self.to - self.from
2170 }
2171
2172 /// Whether an offset falls on this axis.
2173 #[must_use]
2174 pub const fn holds(self, minute: u16) -> bool {
2175 minute >= self.from && minute < self.to
2176 }
2177 }
2178
2179 impl Default for Span {
2180 fn default() -> Self {
2181 Self::DAY
2182 }
2183 }
2184
2185 /// Where a thing sits on a [`Track`], and for how long.
2186 ///
2187 /// The one fact a list cannot carry and the whole reason this primitive exists.
2188 /// A list says what order things come in; a track says a thing starts 135
2189 /// minutes along and lasts 45, which is a different claim and not derivable
2190 /// from the first.
2191 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2192 pub struct Placement {
2193 at: u16,
2194 length: u16,
2195 }
2196
2197 impl Placement {
2198 /// A placement, clamped to a drawable one.
2199 ///
2200 /// Zero length becomes one for the same reason [`Span::new`] clamps: a
2201 /// zero-height thing is invisible rather than expressive, and every
2202 /// renderer would need its own guard.
2203 #[must_use]
2204 pub const fn new(at: u16, length: u16) -> Self {
2205 Self {
2206 at,
2207 length: if length == 0 { 1 } else { length },
2208 }
2209 }
2210
2211 /// Offset from the axis origin, matching [`Span`]'s.
2212 #[must_use]
2213 pub const fn at(self) -> u16 {
2214 self.at
2215 }
2216
2217 /// How long it lasts, in its track's unit. Never zero.
2218 #[must_use]
2219 pub const fn length(self) -> u16 {
2220 self.length
2221 }
2222
2223 /// One past its last minute.
2224 #[must_use]
2225 pub const fn end(self) -> u16 {
2226 self.at + self.length
2227 }
2228
2229 /// Whether two placements cover any of the same time.
2230 ///
2231 /// Geometry, and deliberately not a described field. Whether an overlap is
2232 /// a *conflict* is the app's judgment -- a meeting inside a block of free
2233 /// time overlaps and is fine -- and that judgment travels the way every
2234 /// other judgment does, as a [`Tone`] on the thing itself. What a renderer
2235 /// needs in order to lay two things side by side instead of on top of each
2236 /// other is this, and it can compute it.
2237 ///
2238 /// The alternative was a `conflicts: bool` on each entry, which is state
2239 /// that can disagree with the times beside it. Two sources for one fact is
2240 /// how a screen starts rendering a conflict badge on a thing that no longer
2241 /// conflicts.
2242 #[must_use]
2243 pub const fn overlaps(self, other: Self) -> bool {
2244 self.at < other.end() && other.at < self.end()
2245 }
2246 }
2247
2248 /// A time axis: things placed by when they happen, rather than flowed.
2249 ///
2250 /// # Why this is a primitive
2251 ///
2252 /// This crate refused to name it until 2026-08-15, on the argument that a
2253 /// description expressive enough to draw a timeline is a component library
2254 /// wearing a description's name. The refusal is withdrawn, and it is worth
2255 /// being precise about what was wrong with it, because the reasoning it used
2256 /// applies to real cases and should not be discarded with it.
2257 ///
2258 /// What a timeline needs that a [`List`](Region::Pane) does not is **one**
2259 /// thing: placement. Where a thing sits is a fact about the thing, the way a
2260 /// row's primary text is, and it is not derivable from order. Everything else a
2261 /// day view draws -- the labels, the gridlines, the item bodies, the tones --
2262 /// is furniture this vocabulary already names. Measured against goingson's
2263 /// `day-planning-render.js`, the only members it needed and could not get were
2264 /// `at` and `minutes`.
2265 ///
2266 /// So the timeline was never a component library's worth of vocabulary. It was
2267 /// two integers, and the refusal was priced as though it were the whole widget.
2268 /// The test that matters is not "does this shape look complicated" but "how
2269 /// many members does it actually add, and are they facts or presentation".
2270 /// Slot heights, gridline colour, how overlaps stack and which hour scrolls
2271 /// into view on open are all presentation and all stay the renderer's, which is
2272 /// why they are absent here.
2273 ///
2274 /// # What it does not carry
2275 ///
2276 /// No pixel measure, no scroll offset, no drag affordance. A renderer draws the
2277 /// span at whatever density its host uses; `makeover-geometry` owns that the
2278 /// way it owns everything else measured in pixels.
2279 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2280 pub struct Track {
2281 /// The window the axis covers.
2282 pub span: Span,
2283 /// The granularity a thing can be placed on, in minutes.
2284 ///
2285 /// goingson's day view is 15, giving 96 slots across a day. A renderer uses
2286 /// it to decide where gridlines fall and what a drop lands on; it does not
2287 /// constrain [`Placement`], because data arriving from a calendar does not
2288 /// respect anyone's grid.
2289 pub slot: u16,
2290 /// How often the axis labels itself, in its own unit.
2291 ///
2292 /// 60 gives an hourly ruler over a 15-minute grid, which is the common
2293 /// shape and the reason this is separate from `slot`. Zero means an
2294 /// unlabelled axis.
2295 pub tick: u16,
2296 /// What `span`, `slot`, `tick` and every [`Placement`] on it count.
2297 ///
2298 /// The one field here a renderer cannot derive, and the reason it exists:
2299 /// [`fraction`](Self::fraction) is unit-agnostic, so a day-granularity
2300 /// track produced correct geometry under an hours-and-minutes ruler until
2301 /// this was added. Geometry never needed it; a label always did.
2302 pub unit: Unit,
2303 }
2304
2305 impl Track {
2306 /// An ordinary day: midnight to midnight, quarter-hour slots, hourly ticks.
2307 pub const DAY: Self = Self {
2308 span: Span::DAY,
2309 slot: 15,
2310 tick: 60,
2311 unit: Unit::Minutes,
2312 };
2313
2314 /// A track over `span`, with the day's usual granularity.
2315 #[must_use]
2316 pub const fn over(span: Span) -> Self {
2317 Self {
2318 span,
2319 slot: 15,
2320 tick: 60,
2321 unit: Unit::Minutes,
2322 }
2323 }
2324
2325 /// A strip of whole days: one slot a day, a label a week.
2326 ///
2327 /// The shape a stretch of leave or a sprint is drawn on. Not a calendar --
2328 /// it does not wrap into weeks, and the crate header says why that
2329 /// distinction is the whole of what a month grid still has over this.
2330 #[must_use]
2331 pub const fn days(span: Span) -> Self {
2332 Self {
2333 span,
2334 slot: 1,
2335 tick: 7,
2336 unit: Unit::Days,
2337 }
2338 }
2339
2340 /// How many slots the axis holds.
2341 ///
2342 /// Rounded up, so a span that does not divide evenly by `slot` still has a
2343 /// slot covering its tail rather than dropping it. Never zero: `slot` of 0
2344 /// reads as one slot spanning the whole axis rather than a division by
2345 /// zero, since a renderer asking this question has already committed to
2346 /// drawing something.
2347 #[must_use]
2348 pub const fn slots(self) -> u16 {
2349 if self.slot == 0 {
2350 1
2351 } else {
2352 self.span.length().div_ceil(self.slot)
2353 }
2354 }
2355
2356 /// Where a placement sits on the axis, as a fraction from 0.0 to 1.0.
2357 ///
2358 /// The one calculation every renderer would otherwise write itself, and the
2359 /// place the three would drift apart. Clamped, so a placement outside the
2360 /// span draws at the edge rather than off it -- an event running past
2361 /// midnight is a real thing and truncating it is better than either
2362 /// panicking or drawing it somewhere impossible.
2363 #[must_use]
2364 pub fn fraction(self, minute: u16) -> f32 {
2365 let span = f32::from(self.span.length());
2366 let offset = f32::from(minute.saturating_sub(self.span.from()));
2367 (offset / span).clamp(0.0, 1.0)
2368 }
2369 }
2370
2371 impl Default for Track {
2372 fn default() -> Self {
2373 Self::DAY
2374 }
2375 }
2376
2377 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2378 pub struct Act<'a> {
2379 /// What the control says.
2380 pub label: &'a str,
2381 /// The key that reaches it where a host has keys.
2382 ///
2383 /// The one member written for a terminal before there was one. A webview
2384 /// hangs it off `accesskey` or ignores it; a terminal has nothing else to
2385 /// offer, so this is the whole of how a control is reached there.
2386 pub key: Option<&'a str>,
2387 /// What pressing it means. [`Tone::Danger`] is the destructive one.
2388 pub tone: Tone,
2389 /// Disabled, or nothing said.
2390 ///
2391 /// [`State::Disabled`] is what changes what a renderer may do: see
2392 /// [`State::suppresses_interaction`], which is what says a disabled control
2393 /// is drawn and not reachable. It has been the only member since 0.19.0,
2394 /// and a control's focus is not sayable here at all — see the crate header,
2395 /// "Reach, focus and the focus ring".
2396 pub state: Option<State>,
2397 }
2398
2399 impl<'a> Act<'a> {
2400 /// An ordinary control, reachable, with no key.
2401 #[must_use]
2402 pub const fn new(label: &'a str) -> Self {
2403 Self {
2404 label,
2405 key: None,
2406 tone: Tone::Neutral,
2407 state: None,
2408 }
2409 }
2410
2411 /// The key that reaches it.
2412 #[must_use]
2413 pub const fn key(mut self, key: &'a str) -> Self {
2414 self.key = Some(key);
2415 self
2416 }
2417
2418 /// What pressing it means.
2419 #[must_use]
2420 pub const fn tone(mut self, tone: Tone) -> Self {
2421 self.tone = tone;
2422 self
2423 }
2424
2425 /// Focus, or disabled.
2426 #[must_use]
2427 pub const fn state(mut self, state: State) -> Self {
2428 self.state = Some(state);
2429 self
2430 }
2431
2432 /// Whether the control is drawn and does not answer.
2433 #[must_use]
2434 pub fn disabled(&self) -> bool {
2435 self.state.is_some_and(State::suppresses_interaction)
2436 }
2437 }
2438
2439 /// A named part of a screen.
2440 ///
2441 /// The thing `makeover-geometry` deliberately does not name: it names the space
2442 /// *between* things by relationship, and nothing named the things. Six named
2443 /// members, taken from what the two webview apps actually use, plus
2444 /// [`Region::Bespoke`] for the parts no description should reach. Both apps'
2445 /// `layout.css` currently names exactly two things, `.raised` and `.well`, so
2446 /// this layer is absent rather than divergent, which makes it the cheapest of
2447 /// the schemas to add and the easiest to over-build.
2448 ///
2449 /// `#[non_exhaustive]` arrives with [`Region::Widget`], the pairing [`RowPart`]
2450 /// made at 0.9.0 and [`Readiness`] at 0.12.0, and for the same reason: the
2451 /// member after this one should not be a lockstep event across three renderers.
2452 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
2453 #[non_exhaustive]
2454 pub enum Region<'a> {
2455 /// A full-width strip with a title slot and an actions cluster, either of
2456 /// which may be empty. goingson's `.page-header`, Balanced Breakfast's
2457 /// `.header` and `.detail-header` are all this, differing only in which
2458 /// slots they fill.
2459 Band,
2460 /// A persistent column beside the content, holding navigation.
2461 Sidebar,
2462 /// A region of content with its own scroll.
2463 Pane,
2464 /// Things that belong together, and nothing else.
2465 ///
2466 /// The block [`Heading::Section`] has been naming since 0.2.0 without the
2467 /// vocabulary being able to contain it. A section heading is a leaf sitting
2468 /// *beside* the things it names, so nothing said where a section started or
2469 /// ended and a renderer learned one had ended only because the next heading
2470 /// arrived.
2471 ///
2472 /// # The measurement
2473 ///
2474 /// 41 [`Heading::Section`] sites across the ten screens described through
2475 /// the router, not one of them contained. audiofiles' settings screen is the
2476 /// clearest: one pane holding a heading, a field, a heading, two toggles, a
2477 /// heading, a toggle and a heading, which is four sections and no
2478 /// containers. Under the hand-written CSS the ports are replacing the same
2479 /// block is spelled `.settings-section` in goingson, `.form-section` and
2480 /// `.content-section` in the MNW server, `.help-section` in Balanced
2481 /// Breakfast: three apps, four names, one shape.
2482 ///
2483 /// # Why the existing members were the wrong answer
2484 ///
2485 /// [`Pane`](Self::Pane) is what apps reached for, and it is 28 of the 45
2486 /// regions in the described screens. It claims a scroll of its own and
2487 /// [`Depth::Well`], so four settings groups inside a pane are four wells
2488 /// inside a well and four scroll contexts. Neither claim is true of a group.
2489 ///
2490 /// [`Widget`](Self::Widget) is wrong from the other side. Its own docs say a
2491 /// widget is never how a primitive gets added by the back door, and a run of
2492 /// related controls under a heading is furniture any app would have, which
2493 /// is the generic-against-bespoke bar a primitive has to clear.
2494 ///
2495 /// # What it does not carry
2496 ///
2497 /// **A heading.** A group usually has one and it is an ordinary node in the
2498 /// body, the way it already was. A group of related toggles with no heading
2499 /// is a real thing and a mandatory slot would forbid it.
2500 ///
2501 /// **A depth.** [`Depth::Flat`], on [`Bespoke`](Self::Bespoke)'s reasoning:
2502 /// it inherits, and an app that wants its group in a well puts it in a
2503 /// [`Pane`](Self::Pane), which composes rather than adding a knob here.
2504 ///
2505 /// **A colour.** Distinguishing sibling groups by colour is the thing this
2506 /// member was asked for and it is deliberately not stated here. The
2507 /// description says these things belong together; which of the theme's
2508 /// categorical colours a renderer reaches for, and whether it reaches for
2509 /// one at all, is derived from sibling order at the renderer. A terminal
2510 /// that tints nothing and separates with a rule is honouring this.
2511 Group,
2512 /// Two panes side by side, where the left chooses what the right shows.
2513 Split,
2514 /// Peer regions across, all of them equals.
2515 ///
2516 /// A kanban board's columns, and the shape [`Split`](Self::Split) is not:
2517 /// a split's two panes stand in a master-detail relationship, where the
2518 /// left chooses what the right shows. These choose nothing about each
2519 /// other. Each is a whole region and the set is the arrangement.
2520 ///
2521 /// # What it does not carry
2522 ///
2523 /// **How many.** The children say, and a count here would be a second
2524 /// source for something the description already states by containing them.
2525 ///
2526 /// **How wide.** Peers are equal by definition, so there is no [`Share`] to
2527 /// state. A board whose columns wanted different widths would be a
2528 /// different member, and no app has one.
2529 ///
2530 /// **What happens when there is no room.** Scroll across, wrap, or collapse
2531 /// to one column at a time: all three are right on some host, none is
2532 /// derivable from the description, and every one of them is presentation.
2533 /// A terminal that stacks them vertically is honouring this, not degrading
2534 /// it.
2535 ///
2536 /// # Why it is not an `Arrangement`
2537 ///
2538 /// [`Arrangement`] is the page's shape, and a board is usually a region
2539 /// *inside* a page that also has a band over it. Naming it here composes;
2540 /// naming it there would make a screen either a board or a list-detail and
2541 /// never a band above a board. It also keeps [`Arrangement::share`]
2542 /// meaningful, which a peer arrangement has no answer for.
2543 Columns,
2544 /// A set of panes, one visible at a time, and a [`Selector::Tabs`] that
2545 /// chooses between them.
2546 ///
2547 /// Says nothing about where the strip sits. A row over the panes, a column
2548 /// beside them, a wrapped run of links under them: all three are the same
2549 /// member drawn by a renderer that knows its host, the way the strip's
2550 /// overflow is.
2551 TabGroup,
2552 /// Content over a scrim, taking input until dismissed.
2553 Modal,
2554 /// A region this crate names the *place* of and nothing else. The app owns
2555 /// what goes in it.
2556 ///
2557 /// The escape hatch, and the thing that keeps the description honest about
2558 /// its own limits. A day-plan timeline, a kanban board, a calendar and the
2559 /// paint interaction over the timeline are not describable here and are not
2560 /// going to become describable: a description expressive enough to produce
2561 /// a timeline is a widget library wearing a description's name.
2562 ///
2563 /// But a screen containing one still has to be a screen. Without this
2564 /// member the description covers only the boring screens, and the four that
2565 /// make goingson worth using would need a second, undescribed path beside
2566 /// the router. Two paths is how the vocabulary starts drifting from the app
2567 /// again, which is the exact failure this crate exists to end.
2568 ///
2569 /// So the description says "a thing called `day-plan` goes here" and stops.
2570 /// The name is opaque: this crate never interprets it, and no renderer is
2571 /// expected to know what it means beyond handing the space over.
2572 Bespoke {
2573 /// What the app calls it. Never interpreted here.
2574 name: &'a str,
2575 },
2576 /// A named assembly of things the vocabulary already says.
2577 ///
2578 /// The third tier, between a primitive and [`Bespoke`](Self::Bespoke).
2579 /// Stated by Max 2026-08-12 answering the carousel: "something in between a
2580 /// primitive and a bespoke interface, like a widget, which is just an
2581 /// assembly of primitives." Full note: wiki `widget-tier`.
2582 ///
2583 /// # What separates it from the two members either side
2584 ///
2585 /// A primitive is a thing every renderer draws from scratch, and the test
2586 /// it has to pass is that every host has an honest answer. A carousel fails
2587 /// that test — a terminal has no carousel — which is the same refusal
2588 /// `Node::Html` got and is why the carousel sat unsayable for months.
2589 ///
2590 /// [`Bespoke`](Self::Bespoke) fails it from the other side. Bespoke is for
2591 /// what one app owns and nobody will build twice, and it carries *no*
2592 /// contents: the description names the place and stops. A carousel is
2593 /// furniture any app would have, and every part of it — an ordered set of
2594 /// frames, a position, prev and next, a strip of position indicators — is
2595 /// already sayable. Only the assembly had no name.
2596 ///
2597 /// So this member is the pair the other two are not: a name **and**
2598 /// contents. The contents are the assembly, in the region's own body, said
2599 /// in members that already exist.
2600 ///
2601 /// # Why the name does not have to be understood
2602 ///
2603 /// A renderer that recognises the name draws it the way its host does it: a
2604 /// carousel in a webview, a pager with a count in a terminal, a selector in
2605 /// egui. A renderer that does not recognise it walks the body, which is
2606 /// primitives all the way down and which it can already draw.
2607 ///
2608 /// That is what lets the widget set be **open** without every renderer
2609 /// knowing every widget. An unrecognised widget degrades to its assembly
2610 /// instead of failing, so a second or third party can name one without
2611 /// three renderers releasing in lockstep to accept it. Contrast
2612 /// [`Bespoke`](Self::Bespoke), which no renderer can degrade: there is
2613 /// nothing under it to fall back to.
2614 ///
2615 /// # What it does not do
2616 ///
2617 /// A widget is an assembly of things the vocabulary *already* says, so it
2618 /// buys no expressive power. Anything needing a member the vocabulary does
2619 /// not have is a finding about the vocabulary, and the answer to a finding
2620 /// is to add the member. A widget is never the way a primitive gets added
2621 /// by the back door.
2622 ///
2623 /// This used to say "it does not make a timeline describable, and the
2624 /// refusal in the crate header stands unchanged". The timeline is
2625 /// describable as of 2026-08-15 -- see [`Track`] -- and it got there the
2626 /// way the paragraph above says it should have: by adding the two members
2627 /// that were missing, not by dressing the screen up as an assembly.
2628 Widget {
2629 /// What the assembly is called. This crate never interprets it, and a
2630 /// renderer is free not to know it.
2631 name: &'a str,
2632 },
2633 }
2634
2635 impl<'a> Region<'a> {
2636 /// How the region sits on what is behind it.
2637 #[must_use]
2638 pub const fn depth(self) -> Depth {
2639 match self {
2640 Self::Band | Self::Sidebar | Self::Split | Self::TabGroup => Depth::Flat,
2641 // Flat, and it inherits. A group says its contents belong together
2642 // and says nothing about the surface they sit on, so a group in a
2643 // pane is in a well and a group on the page is on the page. An app
2644 // wanting one lifted puts it in a `Pane`.
2645 Self::Group => Depth::Flat,
2646 // Flat, and it is the container rather than the columns. Each
2647 // column is its own region and brings its own depth; a well here
2648 // would put a second edge around a row of wells.
2649 Self::Columns => Depth::Flat,
2650 // A pane is looked into, the same as a table body or a tag tree.
2651 Self::Pane => Depth::Well,
2652 Self::Modal => Depth::Raised,
2653 // Flat because it inherits: a bespoke region takes the depth of
2654 // whatever frames it. An app that wants its timeline in a well puts
2655 // it in a `Pane`, which composes rather than adding a knob here.
2656 //
2657 // A widget inherits for the same reason and it matters more here,
2658 // because a widget is drawn by whichever renderer recognises it. A
2659 // depth set here would be this crate deciding that a carousel is
2660 // raised on every host, which is the kind of value the deferral
2661 // rule exists to refuse.
2662 Self::Bespoke { .. } | Self::Widget { .. } => Depth::Flat,
2663 }
2664 }
2665
2666 /// Whether this crate can say anything about the region's contents.
2667 ///
2668 /// A renderer walks the description and hands every region it understands
2669 /// to the right drawing code. This is how it tells the two apart, and the
2670 /// reason it is a method rather than a `matches!` at each renderer: there
2671 /// is exactly one opaque member and there should stay exactly one.
2672 ///
2673 /// [`Widget`](Self::Widget) is described, and that is the whole of what
2674 /// separates it from [`Bespoke`](Self::Bespoke) here. Both carry a name
2675 /// this crate never interprets; only one of them carries contents under it.
2676 /// A renderer that does not recognise a widget's name still walks its body,
2677 /// so there is nothing for it to hand over and nothing it cannot draw.
2678 #[must_use]
2679 pub const fn described(self) -> bool {
2680 !matches!(self, Self::Bespoke { .. })
2681 }
2682
2683 /// The name an app gave this region, if it gave one.
2684 ///
2685 /// [`Bespoke`](Self::Bespoke) and [`Widget`](Self::Widget) are the two
2686 /// members that carry a name, for two different purposes: one says what the
2687 /// app will fill the space with, the other says what the assembly under it
2688 /// is called. A renderer dispatching on either wants the string without
2689 /// caring which member it came from, and writing that `matches!` at each
2690 /// renderer is how the two drift apart.
2691 #[must_use]
2692 pub const fn name(self) -> Option<&'a str> {
2693 match self {
2694 Self::Bespoke { name } | Self::Widget { name } => Some(name),
2695 // Spelled out rather than a wildcard, so a member added later has
2696 // to answer whether it carries a name instead of inheriting `None`
2697 // by sitting under a `_`.
2698 Self::Band
2699 | Self::Sidebar
2700 | Self::Pane
2701 | Self::Group
2702 | Self::Split
2703 | Self::Columns
2704 | Self::TabGroup
2705 | Self::Modal => None,
2706 }
2707 }
2708 }
2709
2710 /// How many of a region's children are visible at once.
2711 ///
2712 /// `4dcd241b`. Three findings turned out to be one sentence the vocabulary
2713 /// could not say: *this region holds several children and shows some of them,
2714 /// and the reader can change which.* [`Region::TabGroup`] existed with nothing
2715 /// saying which tab was open, a carousel had nothing saying which frame was up,
2716 /// and a disclosure had nothing saying whether its one child was showing at all.
2717 ///
2718 /// Because the fact lived nowhere, a renderer had two moves: hardcode a widget
2719 /// name, or draw every child. That is what put per-widget code in renderers, and
2720 /// it was the missing member rather than the widget tier that put it there.
2721 ///
2722 /// # What is here and what is not
2723 ///
2724 /// The *kind*, and only the kind. Which child is currently up is the current
2725 /// answer, and a layer that defers every address does not hold the current
2726 /// answer either — the split [`Selector`] already makes, where this crate says
2727 /// what kind of chooser a thing is and the router says which option is picked.
2728 /// So a holder of regions carries the index and the per-child label beside this.
2729 ///
2730 /// # What a renderer does with it
2731 ///
2732 /// Derives its chrome, once, for every widget rather than per name:
2733 ///
2734 /// - Children carrying labels get a strip of the labels, the current one marked.
2735 /// - Children carrying none get previous, position, next.
2736 /// - [`AtMostOne`](Self::AtMostOne) over one child gets a summary line that
2737 /// opens.
2738 ///
2739 /// The name on [`Region::Widget`] survives as app vocabulary, for a renderer
2740 /// that wants to do something *special* with one, which is what it should have
2741 /// been from the start.
2742 ///
2743 /// Degradation runs the way it already did: a renderer ignoring this draws every
2744 /// child, which is more content rather than less.
2745 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
2746 #[non_exhaustive]
2747 pub enum Showing {
2748 /// Every child, in order. What every region did before this existed.
2749 #[default]
2750 All,
2751 /// Exactly one. A carousel, a tab group.
2752 One,
2753 /// One, or none. A disclosure, which is closed until it is opened.
2754 AtMostOne,
2755 }
2756
2757 impl Showing {
2758 /// Whether the reader can change which child is up.
2759 ///
2760 /// The question every renderer's region arm asks before deriving any
2761 /// chrome, and a method rather than a `matches!` at each renderer for
2762 /// [`Region::name`]'s reason: three renderers writing the same comparison is
2763 /// how they come to disagree about a member added later.
2764 #[must_use]
2765 pub const fn selective(self) -> bool {
2766 !matches!(self, Self::All)
2767 }
2768
2769 /// Whether showing nothing is a legal state.
2770 ///
2771 /// True only for [`AtMostOne`](Self::AtMostOne). A renderer needs this to
2772 /// know whether its control closes as well as moves: a carousel's row moves
2773 /// between frames and never reaches empty, and a disclosure's summary line
2774 /// is the same control wearing its closed state.
2775 #[must_use]
2776 pub const fn dismissible(self) -> bool {
2777 matches!(self, Self::AtMostOne)
2778 }
2779 }
2780
2781 /// A window onto a sequence: where it starts, how much it covers, and how long
2782 /// the sequence is when that is known.
2783 ///
2784 /// The mechanism under two things the vocabulary deliberately keeps apart. A
2785 /// carousel is a window of one frame over children that are all present; a
2786 /// paged list is a window of a page over rows most of which were never fetched.
2787 /// Those are different facts and they stay different types — [`Showing`] says
2788 /// which child is up, [`Paging`] says where a reader is in a query — but the
2789 /// arithmetic underneath is one piece of code, so a terminal and a browser
2790 /// cannot come to disagree about which frame is last.
2791 ///
2792 /// # Why `of` is optional and `count` is not
2793 ///
2794 /// `count` is what is on screen and is therefore always known. `of` is the
2795 /// length of the thing being windowed, and a host that cannot count says so by
2796 /// leaving it empty **for the life of the screen**. It is never "not counted
2797 /// yet": see "First paint is final paint" in the crate header. A total that
2798 /// turns up on a later pass widens the text that prints it.
2799 ///
2800 /// # Clamping
2801 ///
2802 /// Every derivation clamps rather than refusing, and a zero `count` answers
2803 /// `None` rather than dividing. A window past the end is a bug in the host, and
2804 /// a renderer that answered it by drawing nothing would report a region that
2805 /// vanished, which is the hardest kind of bug to find from what is on screen.
2806 /// [`Share::percent`] clamps for the same reason.
2807 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
2808 pub struct Window {
2809 /// The index into the sequence where the window starts.
2810 pub from: usize,
2811 /// How many the window covers. One, for a carousel.
2812 pub count: usize,
2813 /// How long the sequence is, when the host can say.
2814 pub of: Option<usize>,
2815 }
2816
2817 impl Window {
2818 /// A window of `count`, starting at `from`, over a sequence of unknown
2819 /// length.
2820 #[must_use]
2821 pub const fn new(from: usize, count: usize) -> Self {
2822 Self {
2823 from,
2824 count,
2825 of: None,
2826 }
2827 }
2828
2829 /// How long the sequence is.
2830 #[must_use]
2831 pub const fn of(mut self, of: usize) -> Self {
2832 self.of = Some(of);
2833 self
2834 }
2835
2836 /// One item of a sequence whose length is known. A carousel frame.
2837 #[must_use]
2838 pub const fn frame(at: usize, of: usize) -> Self {
2839 Self {
2840 from: at,
2841 count: 1,
2842 of: Some(of),
2843 }
2844 }
2845
2846 /// Which window this is, counting from zero.
2847 ///
2848 /// `None` when `count` is zero, which is the only input with no answer
2849 /// rather than a clamped one.
2850 #[must_use]
2851 pub const fn index(self) -> Option<usize> {
2852 if self.count == 0 {
2853 return None;
2854 }
2855 Some(self.from / self.count)
2856 }
2857
2858 /// How many windows the sequence holds.
2859 ///
2860 /// `None` unless both the length and a non-zero `count` are known. A
2861 /// partial answer here would be a renderer drawing "of 0".
2862 #[must_use]
2863 pub const fn windows(self) -> Option<usize> {
2864 match self.of {
2865 Some(of) if self.count > 0 => Some(of.div_ceil(self.count)),
2866 _ => None,
2867 }
2868 }
2869
2870 /// Whether anything sits before this window.
2871 #[must_use]
2872 pub const fn has_before(self) -> bool {
2873 self.from > 0
2874 }
2875
2876 /// How many sit after this window, when the length is known.
2877 ///
2878 /// Here rather than in each renderer for [`Showing::selective`]'s reason:
2879 /// three of them writing the same subtraction is how they come to disagree,
2880 /// and this one has an underflow in it for whoever writes it fourth.
2881 #[must_use]
2882 pub const fn after(self) -> Option<usize> {
2883 match self.of {
2884 Some(of) => Some(of.saturating_sub(self.from.saturating_add(self.count))),
2885 None => None,
2886 }
2887 }
2888
2889 /// Whether anything sits after it.
2890 ///
2891 /// `true` when the length is unknown: a host that cannot count cannot rule
2892 /// out more, and offering a way forward that turns out to be empty is the
2893 /// cheaper of the two mistakes.
2894 #[must_use]
2895 pub const fn has_after(self) -> bool {
2896 match self.of {
2897 Some(of) => self.from.saturating_add(self.count) < of,
2898 None => true,
2899 }
2900 }
2901
2902 /// The window with `from` brought inside the sequence.
2903 ///
2904 /// A no-op when the length is unknown, since there is nothing to clamp
2905 /// against.
2906 #[must_use]
2907 pub const fn clamped(mut self) -> Self {
2908 if let Some(of) = self.of
2909 && self.from >= of
2910 {
2911 // `max(1)` by hand: `Ord::max` is not const yet, and a zero-count
2912 // window would otherwise clamp onto the end rather than inside it.
2913 let step = if self.count == 0 { 1 } else { self.count };
2914 self.from = of.saturating_sub(step);
2915 }
2916 self
2917 }
2918 }
2919
2920 /// Where a reader is in a set that arrived in parts.
2921 ///
2922 /// A [`Window`] wearing the paged reading of itself. Distinct from a carousel's
2923 /// window at the top level on purpose, because the intent differs and a call
2924 /// site should say which one it means, while the arithmetic below is shared so
2925 /// the two cannot drift apart.
2926 ///
2927 /// # The two idioms, and which one a renderer may draw
2928 ///
2929 /// Load-more and numbered pages are both this type. Which is honest is
2930 /// [`paged`](Self::paged): a set whose page size is known can be drawn as
2931 /// "Page 3 of 8", and one without can only be drawn as "150 of 400" and a way
2932 /// forward. Saying it here rather than letting each renderer guess is the point
2933 /// — three renderers inferring it from the numbers is how they come to disagree.
2934 ///
2935 /// # What it does not carry
2936 ///
2937 /// No addresses. `makeover-layout` cannot name an action, and the way to ask for
2938 /// the next part is the host's: `quasi_router` pairs this with the addresses the
2939 /// same way `Row` pairs its parts with `Row::activate`. That split is the reason
2940 /// this type is reusable by a carousel, which has nothing to ask.
2941 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
2942 pub struct Paging {
2943 /// The window onto the set.
2944 pub window: Window,
2945 /// Whether the parts are a fixed size, and so whether pages are countable.
2946 ///
2947 /// `false` for load-more, where the window simply grew and "page 2" would
2948 /// name nothing.
2949 pub paged: bool,
2950 }
2951
2952 impl Paging {
2953 /// A page of `per`, starting at `from`.
2954 #[must_use]
2955 pub const fn pages(from: usize, per: usize) -> Self {
2956 Self {
2957 window: Window::new(from, per),
2958 paged: true,
2959 }
2960 }
2961
2962 /// The first `shown`, with more behind them.
2963 ///
2964 /// The load-more shape: the window starts at the beginning and grows, so
2965 /// there is no page to number.
2966 #[must_use]
2967 pub const fn more(shown: usize) -> Self {
2968 Self {
2969 window: Window::new(0, shown),
2970 paged: false,
2971 }
2972 }
2973
2974 /// How many there are altogether.
2975 ///
2976 /// Left unsaid by a host that cannot count, and left unsaid **for good**:
2977 /// a total arriving later widens whatever prints it. See "First paint is
2978 /// final paint" in the crate header.
2979 #[must_use]
2980 pub const fn of(mut self, of: usize) -> Self {
2981 self.window = self.window.of(of);
2982 self
2983 }
2984
2985 /// Which page this is, counting from one, when pages are countable.
2986 ///
2987 /// One-based because it is read aloud. [`Window::index`] is the zero-based
2988 /// form for anyone indexing with it.
2989 #[must_use]
2990 pub const fn page(self) -> Option<usize> {
2991 if !self.paged {
2992 return None;
2993 }
2994 match self.window.index() {
2995 Some(index) => Some(index + 1),
2996 None => None,
2997 }
2998 }
2999
3000 /// How many pages there are, when that is countable.
3001 #[must_use]
3002 pub const fn pages_total(self) -> Option<usize> {
3003 if !self.paged {
3004 return None;
3005 }
3006 self.window.windows()
3007 }
3008
3009 /// How many are on screen.
3010 #[must_use]
3011 pub const fn shown(self) -> usize {
3012 self.window.count
3013 }
3014
3015 /// How many there are, when the host counted.
3016 #[must_use]
3017 pub const fn total(self) -> Option<usize> {
3018 self.window.of
3019 }
3020
3021 /// How many are not shown yet, when the host counted.
3022 ///
3023 /// The figure a load-more control puts in its label. `None` is the honest
3024 /// and common case: a set that cannot say how many more there are still has
3025 /// a way to ask for them.
3026 #[must_use]
3027 pub const fn remaining(self) -> Option<usize> {
3028 self.window.after()
3029 }
3030
3031 /// Whether there is anything further on.
3032 #[must_use]
3033 pub const fn has_more(self) -> bool {
3034 self.window.has_after()
3035 }
3036
3037 /// Whether there is anything back the other way.
3038 #[must_use]
3039 pub const fn has_previous(self) -> bool {
3040 self.window.has_before()
3041 }
3042 }
3043
3044 /// How much of the width an arrangement's first region takes.
3045 ///
3046 /// `e0fd485e`. Nothing said how much room a region got, so every renderer
3047 /// invented its own number and two hosts showing one screen disagreed about
3048 /// its proportions. A webview never noticed, because the stylesheet answered
3049 /// once for every consumer; a terminal has no stylesheet to inherit from, so
3050 /// `quasi-tui` picked 24 columns for a sidebar and 40% for a list pane and
3051 /// neither had anything behind it.
3052 ///
3053 /// # A proportion, never a unit
3054 ///
3055 /// Held as a percentage, and that is the only form it comes in. A description
3056 /// carrying columns would be describing a terminal and one carrying pixels a
3057 /// webview, and the whole point is that both honour the same fact: a terminal
3058 /// resolves it against a column count, a webview writes it into a grid, and
3059 /// neither has to know what the other did.
3060 ///
3061 /// It is not [`makeover_geometry::Ratio`]'s job either, which was the first
3062 /// guess. Geometry is scales that answer the same for every screen and takes
3063 /// no input that would let a sidebar screen differ from a list-detail one.
3064 ///
3065 /// [`makeover_geometry::Ratio`]: https://docs.rs/makeover-geometry
3066 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
3067 pub struct Share(u8);
3068
3069 impl Share {
3070 /// What a sidebar takes, when nobody says otherwise.
3071 ///
3072 /// A quarter. `quasi-tui` drew 24 columns, which is a quarter of a
3073 /// 96-column terminal and about a fifth of a wide one; a quarter is that
3074 /// number said in the form a webview can honour too.
3075 pub const SIDEBAR: Self = Self(25);
3076
3077 /// What the list side of a list-detail takes, when nobody says otherwise.
3078 ///
3079 /// `quasi-tui`'s 40%, which was already a proportion and is the one number
3080 /// this member did not have to invent.
3081 pub const LIST: Self = Self(40);
3082
3083 /// A share of the width, as a percentage.
3084 ///
3085 /// Clamped to 5..=95 rather than refused. A description that asked for a
3086 /// region of nothing is a bug in the app, and a renderer drawing a region
3087 /// zero cells wide reports it as a region that vanished, which is the
3088 /// hardest kind of bug to find from what is on the screen.
3089 #[must_use]
3090 pub const fn percent(percent: u8) -> Self {
3091 Self(if percent < 5 {
3092 5
3093 } else if percent > 95 {
3094 95
3095 } else {
3096 percent
3097 })
3098 }
3099
3100 /// The share as a percentage.
3101 #[must_use]
3102 pub const fn as_percent(self) -> u8 {
3103 self.0
3104 }
3105
3106 /// This share of a width, rounded to the nearest whole unit.
3107 ///
3108 /// What a terminal calls to turn the proportion into columns. At least one,
3109 /// because a region the description named should be visible: a screen
3110 /// 3 columns wide is unusable either way, and a sidebar that is there is a
3111 /// truer picture of the description than a sidebar that is not.
3112 #[must_use]
3113 pub const fn of(self, whole: u16) -> u16 {
3114 let taken = (whole as u32 * self.0 as u32).div_ceil(100);
3115 if taken == 0 { 1 } else { taken as u16 }
3116 }
3117 }
3118
3119 /// How a screen is laid out.
3120 ///
3121 /// Two, and the second is not a variant of the first. goingson is list-detail,
3122 /// Balanced Breakfast is sidebar plus content, and neither app has a third.
3123 /// The tab group is a modifier rather than a member, because goingson uses it
3124 /// *inside* the same content region rather than instead of one.
3125 ///
3126 /// This exists at all because the router has to be able to express a screen
3127 /// rather than only a control. Discovering the arrangement layer missing after
3128 /// the renderers exist is a redesign; naming two now is a morning.
3129 ///
3130 /// # Why the share rides here
3131 ///
3132 /// `e0fd485e`. A share is per-arrangement: how much a sidebar takes and how
3133 /// much a list side takes are different questions, and this enum is the only
3134 /// thing that knows which one is being asked. Geometry would have had to invent
3135 /// a channel to be told.
3136 ///
3137 /// [`list_detail`](Self::list_detail) and
3138 /// [`sidebar_content`](Self::sidebar_content) build these with the default
3139 /// shares, so a screen that has no opinion does not have to have one.
3140 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3141 pub enum Arrangement {
3142 /// A list that chooses what the detail beside it shows.
3143 ListDetail {
3144 /// Whether the detail side is a [`Region::TabGroup`].
3145 tabbed: bool,
3146 /// How much of the width the list side takes.
3147 share: Share,
3148 },
3149 /// Navigation down the side, content filling the rest.
3150 SidebarContent {
3151 /// How much of the width the sidebar takes.
3152 share: Share,
3153 },
3154 }
3155
3156 impl Arrangement {
3157 /// A list and a detail beside it, at the default share.
3158 #[must_use]
3159 pub const fn list_detail(tabbed: bool) -> Self {
3160 Self::ListDetail {
3161 tabbed,
3162 share: Share::LIST,
3163 }
3164 }
3165
3166 /// A sidebar and content beside it, at the default share.
3167 #[must_use]
3168 pub const fn sidebar_content() -> Self {
3169 Self::SidebarContent {
3170 share: Share::SIDEBAR,
3171 }
3172 }
3173
3174 /// How much of the width the first region takes.
3175 #[must_use]
3176 pub const fn share(self) -> Share {
3177 match self {
3178 Self::ListDetail { share, .. } | Self::SidebarContent { share } => share,
3179 }
3180 }
3181
3182 /// The same arrangement, at this share.
3183 #[must_use]
3184 pub const fn with_share(self, share: Share) -> Self {
3185 match self {
3186 Self::ListDetail { tabbed, .. } => Self::ListDetail { tabbed, share },
3187 Self::SidebarContent { .. } => Self::SidebarContent { share },
3188 }
3189 }
3190 }
3191
3192 /// How wide the content of a whole screen runs.
3193 ///
3194 /// `0eccff0d`, and [`Share`]'s sibling one level up: that one says how a
3195 /// screen's width is divided between regions, this says how much of the window
3196 /// the screen uses in the first place. Both are the description's, which is
3197 /// what answering the two together settled.
3198 ///
3199 /// Measured in the MNW server, where 69 of 72 templates carry exactly one of
3200 /// three mutually exclusive classes and the choice is per screen. GoingsOn
3201 /// reaches for `max-width` 56 times and Balanced Breakfast 12, neither with a
3202 /// token for it, so three apps were solving one thing by hand.
3203 ///
3204 /// # Named for the measure, not for MNW's classes
3205 ///
3206 /// A renderer that is not a browser has to answer this too, and `padded-page`
3207 /// tells a terminal nothing. The three say how wide the text runs, which is a
3208 /// question every renderer can answer: a webview with a `max-width`, a terminal
3209 /// with gutters, an immediate-mode frame with its own width.
3210 ///
3211 /// `#[non_exhaustive]` for [`Fill`]'s reason. The set is closed today because
3212 /// the measurement found three, and a fourth arriving should not be a lockstep
3213 /// release across nine repos.
3214 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
3215 #[non_exhaustive]
3216 pub enum Measure {
3217 /// The whole width, with gutters. The default, and 53 of the 69.
3218 ///
3219 /// What a dashboard, a table and a settings screen want: the content is
3220 /// wide because the content *is* wide, and constraining it would waste the
3221 /// window.
3222 #[default]
3223 Wide,
3224 /// Capped at a comfortable page width, centred. 13 of the 69.
3225 ///
3226 /// A form, a sign-in, a purchase. Content that does not get better by
3227 /// getting wider, but is not prose either.
3228 Contained,
3229 /// Capped at a line length that reads well. 3 of the 69.
3230 ///
3231 /// Prose. The narrowest of the three, and the one with a reason outside
3232 /// taste: a line of text past roughly 75 characters costs the reader the
3233 /// return sweep.
3234 Reading,
3235 }
3236
3237 impl Measure {
3238 /// A stable name, for a renderer that needs to spell it.
3239 ///
3240 /// Here rather than in each renderer for [`Sort::as_str`]'s reason: three
3241 /// renderers spelling one enum is three chances to spell it differently.
3242 #[must_use]
3243 pub const fn as_str(self) -> &'static str {
3244 match self {
3245 Self::Wide => "wide",
3246 Self::Contained => "contained",
3247 Self::Reading => "reading",
3248 }
3249 }
3250 }
3251
3252 /// What kind of value a form field takes.
3253 ///
3254 /// The union of the two vocabularies that diverged, which is what triggered
3255 /// this crate. They have since converged on their own: both apps now have a
3256 /// `renderFormField` emitting the same anatomy, and what is left differing is
3257 /// the kind set, the error shape, and whether the return is a string or a node.
3258 ///
3259 /// Validation is deliberately absent. Neither app has a shared story (goingson
3260 /// validates after collecting the form data, with per-field transform hooks;
3261 /// Balanced Breakfast has `required` and nothing else), and a schema that
3262 /// describes fields but not constraints acquires a constraint layer per app,
3263 /// which is exactly how the current divergence started. Naming it absent is a
3264 /// decision; leaving it unmentioned would not be.
3265 /// `#[non_exhaustive]` for the reason [`Fill`] is: renderers match on this and
3266 /// the set keeps growing, so growth must not be a lockstep event. Email, Url
3267 /// and Tel arriving in 0.5.0 is the second growth in two releases.
3268 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3269 #[non_exhaustive]
3270 pub enum FieldKind {
3271 /// A single line of text.
3272 Text,
3273 /// A single line of text that must never be echoed, logged or round-tripped
3274 /// through anything that might persist it.
3275 Secret,
3276 /// A number.
3277 Number,
3278 /// A number inside bounds the user drags across, where the range being
3279 /// visible is the point.
3280 ///
3281 /// Not [`Number`](Self::Number) with [`min`](Field::min) and
3282 /// [`max`](Field::max), which is the reading to resist and is the same
3283 /// resistance [`Radio`](Self::Radio) needed against `Select`. A bounded
3284 /// number and a validated number are different *questions*. A validated
3285 /// number is typed and can be wrong: the bounds are a rule the answer is
3286 /// checked against, and being told "must be at least 1" afterwards is the
3287 /// normal course of it. A range cannot be out of range at all, because the
3288 /// bounds are the control's extent rather than a rule, and the two ends are
3289 /// what the question means — audiofiles asks for a classifier threshold
3290 /// between 0 and 1, where 0 is never and 1 is only-on-certainty, and a typed
3291 /// 0.72 says nothing without both ends on screen beside it.
3292 ///
3293 /// A renderer cannot infer which one is meant from `min`/`max` alone, which
3294 /// is why this is a kind and not an inference: goingson's `min="1"` duration
3295 /// is a validated number and would become a slider.
3296 ///
3297 /// The membership test passes without stretching: a webview emits
3298 /// `<input type="range">`, egui has `Slider`, a terminal draws a bar and
3299 /// takes arrow keys, a CLI takes a bounded argument.
3300 ///
3301 /// # It owes its bounds
3302 ///
3303 /// [`min`](Field::min) and [`max`](Field::max) are `Option` for every other
3304 /// kind and are **required** here, in the sense the description can require
3305 /// anything: [`Field::bounded`] is the check, and a range missing one has no
3306 /// extent for a renderer to draw. What a renderer does with an unbounded
3307 /// range is its own call and both answers are honest — fall back to a typed
3308 /// number, or pick a host default — so this is stated rather than enforced,
3309 /// the way every other constraint here is.
3310 ///
3311 /// [`Field::step`] is the third fact and is genuinely optional: absent, the
3312 /// host's own granularity stands.
3313 ///
3314 /// Added 0.28.0, from audiofiles' classifier thresholds and storage cap
3315 /// picker (`fb93426b`), where four sliders were hand-rolled against a
3316 /// vocabulary that could not say what they were.
3317 Range,
3318 /// One question with two ends: a lower value and an upper one, submitted
3319 /// under two names.
3320 ///
3321 /// "Show me samples between 90 and 130 BPM" has a single answer with two
3322 /// ends, and the ends constrain each other: a minimum above the maximum is
3323 /// not a wrong value, it is an empty result nobody asked for. Described as
3324 /// two [`Number`](Self::Number) fields that is unsayable — nothing says they
3325 /// are one question, so a renderer draws two controls with two labels and no
3326 /// relationship, and [`Field::error`] can only be attached to one side of a
3327 /// fault that belongs to both.
3328 ///
3329 /// Not [`Range`](Self::Range), which was the reading to resist and the
3330 /// resistance is the same one `Range` itself needed against `Number`. A
3331 /// range describes *one* value inside an extent; this describes two, and the
3332 /// extent is a bound on each rather than the question's meaning. The two
3333 /// come apart in the answer: a range has a value, an interval has a pair,
3334 /// and either end may be absent while the other stands.
3335 ///
3336 /// # It states both names
3337 ///
3338 /// [`Field::name`] is the lower end and [`Field::upper_name`] is the upper
3339 /// one, stated rather than derived. Measured 2026-08-21, the two sites in
3340 /// this tree disagree about affix order — audiofiles submits `bpm_min` /
3341 /// `bpm_max` and the MNW server submits `min_price` / `max_price` — so any
3342 /// derived rule picks one and renames the other's parameters. One member
3343 /// instead of a naming convention this crate would then own forever.
3344 ///
3345 /// Direction is carried by which member the name sits in, so nothing
3346 /// separate says which end is which.
3347 ///
3348 /// # What it does not enforce
3349 ///
3350 /// The crossing rule. A lower end above the upper one is describable here
3351 /// and always was, exactly as an out-of-[`min`](Field::min) number is: this
3352 /// crate carries constraints and never checks them, and deciding a value is
3353 /// wrong stays with whoever validated. What the description buys is that the
3354 /// fault now has one place to be reported rather than two.
3355 ///
3356 /// # Both ends take the same facts
3357 ///
3358 /// [`min`](Field::min), [`max`](Field::max), [`step`](Field::step) and
3359 /// [`unit`](Field::unit) describe the axis rather than one end of it, so
3360 /// they are read once and applied to both. Six of audiofiles' filter axes
3361 /// are exactly this: one extent, one unit, one granularity, two ends.
3362 ///
3363 /// The bounds are optional here, unlike `Range`. They are a rule the answer
3364 /// is checked against rather than the control's extent, which is
3365 /// [`Number`](Self::Number)'s arrangement and not a slider's.
3366 ///
3367 /// Added 0.34.0, ruled by Max 2026-08-21, from audiofiles' six filter axes
3368 /// and the MNW server's price pair.
3369 Interval,
3370 /// An email address.
3371 ///
3372 /// Distinct from [`Text`](Self::Text) because the distinction is not
3373 /// decoration: a webview renderer emits `type="email"`, which on a touch
3374 /// device changes the keyboard that appears and turns on the platform's own
3375 /// validation. goingson ships to iOS, so collapsing this into text costs a
3376 /// keyboard with no `@` on it.
3377 ///
3378 /// Added 0.5.0, from goingson's contact form.
3379 Email,
3380 /// A URL. Same reasoning as [`Email`](Self::Email).
3381 ///
3382 /// Added 0.5.0, from goingson's contact-social and contact-feed forms.
3383 Url,
3384 /// A telephone number. Same reasoning as [`Email`](Self::Email), and the
3385 /// clearest case of it: the keyboard is a numeric pad rather than letters.
3386 ///
3387 /// Added 0.5.0, from goingson's contact-phone form.
3388 Tel,
3389 /// A calendar day, with no time of day in it.
3390 ///
3391 /// [`Email`](Self::Email)'s argument, and it carries further: a webview
3392 /// emits `type="date"`, which is a native picker, the platform's own
3393 /// validation, and on a touch device the date keyboard. Described as
3394 /// [`Text`](Self::Text) with a hint reading "YYYY-MM-DD", all three are
3395 /// lost and the hint is doing the platform's job in prose.
3396 ///
3397 /// The membership test passes on every host without stretching: a webview
3398 /// and a Tauri app emit the input, egui has a date picker, a terminal
3399 /// prompts for a day and can validate it, a CLI takes an argument.
3400 ///
3401 /// # The value is ISO 8601, `YYYY-MM-DD`
3402 ///
3403 /// Named here rather than left to each host, because a host that picks
3404 /// differently sends a server something it parses differently, and the
3405 /// failure is silent and per-host. It is `<input type="date">`'s own wire
3406 /// format, so the webview renderer owes nothing to honour it and the other
3407 /// hosts have one spelling to meet. [`DATE_FORMAT`] is the constant, and a
3408 /// test asserts this doc and that constant agree.
3409 ///
3410 /// Added 0.15.0, from the MNW server's git access-token expiry
3411 /// (`user_ssh_keys_tab.html`) and six further sites across the server and
3412 /// goingson.
3413 Date,
3414 /// A calendar day and a time of day together.
3415 ///
3416 /// Apart from [`Date`](Self::Date) because the question is different rather
3417 /// than more precise: "which day does this expire" and "at what moment does
3418 /// this publish" are asked by different screens and answered by different
3419 /// controls. A webview emits `type="datetime-local"` for one and
3420 /// `type="date"` for the other, and a host that collapsed them would ask
3421 /// half the tree for a precision it does not want.
3422 ///
3423 /// Both arrived together on measurement rather than on symmetry: 13 sites
3424 /// of each across the MNW server and goingson, and **zero** of `time`,
3425 /// `month` or `week`, which is why those are not here. A member added for a
3426 /// case nobody has is a member designed against nothing, which is
3427 /// [`File`](Self::File)'s reasoning about `accept` applied to a whole
3428 /// member.
3429 ///
3430 /// # The value is `YYYY-MM-DDTHH:MM`, local, with no zone
3431 ///
3432 /// `<input type="datetime-local">`'s own format, and the "local" is the
3433 /// load-bearing half: the value carries no offset and no `Z`, so the moment
3434 /// it names is only fixed once something supplies a zone. That is the app's
3435 /// business and not the description's. Seconds are absent, which is the
3436 /// browser's own default and is left as the rule rather than restated as a
3437 /// constraint. [`DATETIME_FORMAT`] is the constant.
3438 ///
3439 /// [`Field::min`] and [`Field::max`] already take "the host's own spelling
3440 /// of a bound", so a floor of *not in the past* needs nothing new here: it
3441 /// is a string in this same format.
3442 ///
3443 /// Added 0.15.0, from goingson's snooze picker and day planner and the MNW
3444 /// server's publish-at fields.
3445 DateTime,
3446 /// Several lines of text.
3447 Textarea,
3448 /// Several lines of text the user writes markdown in.
3449 ///
3450 /// The editing counterpart of prose a description carries as markdown
3451 /// source, and the reason it can exist at all is the same one that lets the
3452 /// source be carried: editing markdown is editing text, so a terminal, an
3453 /// immediate-mode host and a webview all have an honest answer, and none of
3454 /// them has to refuse. A kind that meant "rich text" in the WYSIWYG sense
3455 /// would have been a document model, and two of the three hosts would have
3456 /// had to draw something they cannot.
3457 ///
3458 /// What the mark buys over [`Textarea`](Self::Textarea) is that a renderer
3459 /// may offer the affordances markdown has and plain text does not — a
3460 /// preview, a syntax pass, a monospaced face for the source — and that a
3461 /// host reading the value back knows what it is holding. A renderer with
3462 /// none of that draws a textarea, which is why this is additive rather than
3463 /// a second control.
3464 ///
3465 /// It says nothing about **when** the value is saved. Autosave is a clock,
3466 /// clocks are not described here, and the four MNW editors this was measured
3467 /// against each keep their own.
3468 ///
3469 /// Sanitising stays where it already is for markdown that is only displayed:
3470 /// with the renderer, at the point markup is produced. Being described is
3471 /// not a safety property, and a host with its own sanitiser and its own
3472 /// content-security posture still owns both.
3473 ///
3474 /// Added 0.30.0, `f8ad0b32`, from four hand-written MNW section editors —
3475 /// `project-sections.js`, `blog-editor.js`, `partial-item-text-editor.js`
3476 /// and `wizard-item-sections.js` — which are one shape written four times.
3477 Rich,
3478 /// One of a fixed set, offered behind a control that shows one at a time.
3479 Select,
3480 /// One of a fixed set, with every option on screen at once.
3481 ///
3482 /// Not a presentation of [`Select`](Self::Select), which is the reading to
3483 /// resist: what differs is a property of the *question*. A choice that is
3484 /// consequential or irreversible has to be readable without opening
3485 /// anything, because a closed control shows one option and hides the rest,
3486 /// and the one it shows is whichever was current before the user had read
3487 /// the alternatives. audiofiles asks whether a library copies samples into
3488 /// its store or references them where they lie — which cannot be changed
3489 /// afterwards — and had already promoted that out of a checkbox by hand,
3490 /// with a comment giving this reason, before the description could say it.
3491 ///
3492 /// It was described here at 0.8.1 as "the one HTML input type this enum was
3493 /// missing", which was not true then and is not true now: `file` arrived at
3494 /// 0.11.0 and `date` and `datetime-local` at 0.15.0. Everything here is
3495 /// still an `<input type=...>`, a `<select>` or a `<textarea>`, and the way
3496 /// this enum grows is by a site being measured rather than by a list being
3497 /// completed, so "the last one" is not a claim it should make again.
3498 ///
3499 /// Added 0.8.1, from audiofiles' Add Library form.
3500 Radio,
3501 /// On or off.
3502 Checkbox,
3503 /// A file the user picks from wherever the host keeps files.
3504 ///
3505 /// Added 0.11.0, `844b5ae0`, from goingson's project-dashboard attachments
3506 /// column. It was filed as a router finding — a control whose destination is
3507 /// a host capability rather than an address — and splitting it is what made
3508 /// it two answers instead of one member satisfying neither. *Opening* a file
3509 /// is a one-way handoff and needs no new API. *Picking* one returns a value
3510 /// into a write, which is a form concern, which is this.
3511 ///
3512 /// The membership test passes on every host and not by a stretch: a Tauri
3513 /// app opens a native picker, a server renders `<input type="file">`, a
3514 /// terminal prompts for a path, a CLI takes an argument. That is closer to
3515 /// [`Email`](Self::Email), which exists because it changes the keyboard,
3516 /// than to anything bespoke.
3517 ///
3518 /// # The four things an upload says, and where each of them lives
3519 ///
3520 /// | axis | where |
3521 /// |---|---|
3522 /// | what it accepts | [`Field::accept`] |
3523 /// | one file or several | [`Field::multiple`] |
3524 /// | where the bytes go | the router's action, not here |
3525 /// | how far along it is | [`Awaiting`] on that action |
3526 ///
3527 /// Only the first two are this crate's, and that split is the answer to
3528 /// "describe an upload in full" rather than a gap in it. A destination is an
3529 /// address and this crate holds no addresses; progress is a live number and
3530 /// a description is built once, so the number is the renderer's to observe
3531 /// against the size [`Awaiting::amount`] carried before the transfer began.
3532 ///
3533 /// # How the file is handed over is the host's
3534 ///
3535 /// A drop area, a button opening a native picker, a path typed at a prompt:
3536 /// all three are the same field, and every measured site has the first. It
3537 /// is not described for the reason no gesture is — this crate owns no
3538 /// coordinates and no pointer, and a terminal that cannot be dropped on
3539 /// would be refusing a description it can otherwise honour completely.
3540 ///
3541 /// The first two were absent until 0.31.0, and the doc here said why: they
3542 /// were measured rather than deferred, `accept` appearing at zero sites in
3543 /// either app. The count was taken over goingson and Balanced Breakfast, and
3544 /// the MNW server is a third consumer with 14 of them. A member designed
3545 /// against nothing is still the rule; the measurement is what changed.
3546 File,
3547 /// Carried through the form and never shown.
3548 Hidden,
3549 }
3550
3551 /// The wire format a [`FieldKind::Date`] value takes: ISO 8601, `YYYY-MM-DD`.
3552 ///
3553 /// A constant rather than a sentence in a doc comment, because the reason to
3554 /// name the format at all is that a host picking its own would fail silently
3555 /// against a server parsing another. A host that cannot emit the native control
3556 /// still has one spelling to meet, and can say which one it meant.
3557 pub const DATE_FORMAT: &str = "%Y-%m-%d";
3558
3559 /// The wire format a [`FieldKind::DateTime`] value takes: `YYYY-MM-DDTHH:MM`,
3560 /// local, carrying no zone and no seconds.
3561 ///
3562 /// [`DATE_FORMAT`]'s sibling and there for its reason. The absent zone is a
3563 /// property of the value rather than an omission: the moment is not fixed until
3564 /// something outside the description supplies one.
3565 pub const DATETIME_FORMAT: &str = "%Y-%m-%dT%H:%M";
3566
3567 impl FieldKind {
3568 /// Whether the value the kind takes is a moment rather than a string.
3569 ///
3570 /// Named once here for the reason [`offers_options`](Self::offers_options)
3571 /// is: two kinds answer yes, and a host that has to parse or format a value
3572 /// needs to ask without spelling the pair out at each renderer. A third
3573 /// temporal kind should land here and nowhere else.
3574 ///
3575 /// The format each one takes is [`DATE_FORMAT`] and [`DATETIME_FORMAT`].
3576 #[must_use]
3577 pub const fn temporal(self) -> bool {
3578 matches!(self, Self::Date | Self::DateTime)
3579 }
3580
3581 /// Whether the field is drawn at all.
3582 #[must_use]
3583 pub const fn visible(self) -> bool {
3584 !matches!(self, Self::Hidden)
3585 }
3586
3587 /// Whether the value must be kept out of logs and diagnostics.
3588 #[must_use]
3589 pub const fn confidential(self) -> bool {
3590 matches!(self, Self::Secret)
3591 }
3592
3593 /// Where the field's own label sits.
3594 ///
3595 /// A checkbox labels itself on the right of the box; everything else takes
3596 /// a label above. Both webview apps already do this and both special-case
3597 /// it inline, which is the tell that it belongs in the description.
3598 ///
3599 /// A [`Radio`](Self::Radio) is not one of them, and the near-miss is worth
3600 /// naming: its *options* each label themselves, but the field still asks a
3601 /// question above them, so the group takes a label like everything else.
3602 #[must_use]
3603 pub const fn labels_itself(self) -> bool {
3604 matches!(self, Self::Checkbox)
3605 }
3606
3607 /// Whether the kind reads [`Field::options`].
3608 ///
3609 /// Two kinds do, so the pair is named once here rather than spelled out at
3610 /// each renderer and again in [`Field::options`]' own doc, where "every
3611 /// kind but `Select`" was true for exactly one release. A third
3612 /// option-taking kind should land here and nowhere else.
3613 #[must_use]
3614 pub const fn offers_options(self) -> bool {
3615 matches!(self, Self::Select | Self::Radio)
3616 }
3617
3618 /// Whether the value runs to more than one line.
3619 ///
3620 /// Named once here for [`temporal`](Self::temporal)'s reason: two kinds
3621 /// answer yes, every renderer has to ask it before it can size anything,
3622 /// and a `matches!` per renderer is the pair drifting apart one member at a
3623 /// time. What a host does with the markdown, if anything, it reads from the
3624 /// kind itself; this is only whether one line is enough.
3625 #[must_use]
3626 pub const fn multiline(self) -> bool {
3627 matches!(self, Self::Textarea | Self::Rich)
3628 }
3629
3630 /// Whether the value is a file the host picks rather than a string typed
3631 /// into a box.
3632 ///
3633 /// One member answers yes, which is [`visible`](Self::visible)'s and
3634 /// [`confidential`](Self::confidential)'s footing rather than a departure
3635 /// from it: the question gets a name because three renderers ask it before
3636 /// they can read [`Field::accept`] or [`Field::multiple`], and a `matches!`
3637 /// per renderer is where a second file-taking kind would go missing.
3638 #[must_use]
3639 pub const fn takes_files(self) -> bool {
3640 matches!(self, Self::File)
3641 }
3642
3643 /// Whether the value is a quantity, so [`Field::unit`] means something.
3644 ///
3645 /// The numeric kinds and nothing else. A date is a quantity in the sense
3646 /// that it is ordered, and it is not one in the sense that matters here:
3647 /// its unit is fixed by the kind, so `Date` carrying `days` would be the
3648 /// description restating what [`kind`](Field::kind) already said.
3649 ///
3650 /// [`takes_files`](Self::takes_files)'s footing, and for its reason: the
3651 /// renderers ask this before they decide where a unit goes, and a
3652 /// `matches!` per renderer is where the next measurable kind goes missing.
3653 ///
3654 /// Added 0.33.0 with [`Field::unit`]. [`Interval`](Self::Interval) joined at
3655 /// 0.34.0: an axis is measured in something and both its ends are in it.
3656 #[must_use]
3657 pub const fn measurable(self) -> bool {
3658 matches!(self, Self::Number | Self::Range | Self::Interval)
3659 }
3660 }
3661
3662 /// A family of media a file can belong to.
3663 ///
3664 /// Three members, because three is what a media type's own first segment offers
3665 /// that a renderer can do anything with. `text` and `application` are families
3666 /// too and neither buys a disclosure — there is no preview of an
3667 /// `application/octet-stream` — so naming them would be a member added for a
3668 /// case nobody has.
3669 ///
3670 /// It is the answer to "which disclosure", not a validation rule.
3671 /// [`Field::accept`] is what a host filters on.
3672 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3673 #[non_exhaustive]
3674 pub enum Family {
3675 /// A still picture.
3676 Image,
3677 /// Sound.
3678 Audio,
3679 /// Moving pictures, with or without sound.
3680 Video,
3681 }
3682
3683 impl Family {
3684 /// The wildcard media type that means the whole family.
3685 ///
3686 /// `image/*` and its two siblings, which is what the measured sites write
3687 /// and what a webview puts in an `accept` attribute. Named here so the three
3688 /// renderers do not each spell the star.
3689 #[must_use]
3690 pub const fn wildcard(self) -> &'static str {
3691 match self {
3692 Self::Image => "image/*",
3693 Self::Audio => "audio/*",
3694 Self::Video => "video/*",
3695 }
3696 }
3697
3698 /// The family a media type's first segment names, if it is one of these.
3699 ///
3700 /// Case-insensitive on the segment, because a media type is
3701 /// case-insensitive and half the tree writes them lowercase by habit rather
3702 /// than by rule.
3703 #[must_use]
3704 pub fn of_type(media_type: &str) -> Option<Self> {
3705 let (top, _) = media_type.split_once('/')?;
3706 if top.eq_ignore_ascii_case("image") {
3707 Some(Self::Image)
3708 } else if top.eq_ignore_ascii_case("audio") {
3709 Some(Self::Audio)
3710 } else if top.eq_ignore_ascii_case("video") {
3711 Some(Self::Video)
3712 } else {
3713 None
3714 }
3715 }
3716 }
3717
3718 /// One entry in a file field's accept list.
3719 ///
3720 /// Three shapes rather than a string, and all three are in the measured sites:
3721 /// the MNW server writes `image/*`, `image/jpeg,image/png,image/webp`,
3722 /// `.zip,.dmg,.exe,.appimage,.deb,.tar.gz,.clap,.vst3` and, in one place,
3723 /// `.csv,text/csv`. A single string would carry all of them and answer nothing
3724 /// about any of them.
3725 ///
3726 /// # Why the list is not just a filter
3727 ///
3728 /// It is read twice. Once to decide what the picker offers, which any of the
3729 /// three shapes serves, and once to decide **which disclosure** the field gets:
3730 /// a preview for a picture, a duration or a waveform for a sound. There is one
3731 /// upload shape and a media upload is that shape with more of it shown, so the
3732 /// accept list is what says which more. [`family`](Self::family) is that
3733 /// question answered once here instead of a media-type parser in each renderer.
3734 ///
3735 /// # A suffix names no family, on purpose
3736 ///
3737 /// `.mp3` is audio in fact, and nothing here says so. A suffix-to-family table
3738 /// in a published crate is a mapping that goes stale, disagrees with the host's
3739 /// own idea of what a file is, and is wrong the first time somebody hands it a
3740 /// container. A call site that wants a picture's preview writes
3741 /// [`Family::Image`] or `image/jpeg`; a call site listing installer suffixes
3742 /// wants no disclosure anyway, which is the measured case.
3743 ///
3744 /// Added 0.31.0, `f7261a5a`.
3745 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3746 #[non_exhaustive]
3747 pub enum Accepted<'a> {
3748 /// Every file of a family: `image/*` and its siblings.
3749 Family(Family),
3750 /// One media type, written the way a media type is written:
3751 /// `image/jpeg`, `text/csv`.
3752 Type(&'a str),
3753 /// One file-name suffix, written with its leading dot: `.zip`, `.tar.gz`.
3754 ///
3755 /// A suffix and not an extension, because `.tar.gz` is a measured site and
3756 /// is two dots.
3757 Suffix(&'a str),
3758 }
3759
3760 impl<'a> Accepted<'a> {
3761 /// The family this entry belongs to, when it names one.
3762 ///
3763 /// [`None`] for a [`Suffix`](Self::Suffix) and for any media type outside
3764 /// the three families, which is the honest answer rather than a missing
3765 /// one: the description did not say.
3766 #[must_use]
3767 pub fn family(self) -> Option<Family> {
3768 match self {
3769 Self::Family(family) => Some(family),
3770 Self::Type(media_type) => Family::of_type(media_type),
3771 Self::Suffix(_) => None,
3772 }
3773 }
3774
3775 /// How a host that wants one string writes this entry.
3776 ///
3777 /// A webview's `accept` attribute takes exactly these spellings, and a
3778 /// terminal listing what it will take reads the same words.
3779 #[must_use]
3780 pub const fn as_str(self) -> &'a str {
3781 match self {
3782 Self::Family(family) => family.wildcard(),
3783 Self::Type(text) | Self::Suffix(text) => text,
3784 }
3785 }
3786 }
3787
3788 /// One option offered by a field [`FieldKind::offers_options`] accepts.
3789 ///
3790 /// Two strings, because the submitted value and the read label are different
3791 /// facts and every renderer that has tried to collapse them has had to
3792 /// un-collapse them later. `makeover-webview` invented this shape writing its
3793 /// form emitter and it is taken here unchanged; moving it down rather than
3794 /// re-deriving it is the point, since the second and third renderers were each
3795 /// going to arrive at a near-miss of it.
3796 /// `#[non_exhaustive]` as of 0.28.0, which every other type here that a
3797 /// renderer matches or builds has carried for releases. It was the omission
3798 /// that made [`unavailable`](Self::unavailable) a breaking change across 40
3799 /// literal sites in six repos, and it arrives with that member so the price is
3800 /// paid once and never again.
3801 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3802 #[non_exhaustive]
3803 pub struct Choice<'a> {
3804 /// What is submitted.
3805 pub value: &'a str,
3806 /// What is read.
3807 pub label: &'a str,
3808 /// Why it cannot be picked right now, when it cannot.
3809 ///
3810 /// One member rather than an `available: bool` beside a reason, and the
3811 /// conflation is the point: an option greyed out with no explanation is a
3812 /// dead end the user cannot act on, and it is exactly the state the app
3813 /// that found this gap had to patch by hand with a line of prose under the
3814 /// control. Making the reason mandatory means the description cannot say
3815 /// the useless half.
3816 ///
3817 /// The option stays in the list. Dropping it is what an app does today, and
3818 /// it costs the user the knowledge that the thing exists at all —
3819 /// audiofiles' multi-sample mode appears on its own once a second sample is
3820 /// dropped, so a user who never sees it never learns what to drop.
3821 ///
3822 /// **Not [`Field::error`], and not [`Field::hint`].** An error is about the
3823 /// answer and a hint is standing help for the whole question; this is about
3824 /// one option among several, which is the level neither of those reaches.
3825 ///
3826 /// **Not disabled-the-state.** `State::Disabled` is about a whole field
3827 /// refusing to answer. This says the field is live and one of its answers
3828 /// is not available yet, which is a different sentence and the reason the
3829 /// tone rule matters here: the *other* options are still usable.
3830 ///
3831 /// Added 0.28.0, from audiofiles' instrument mode selector (`e761833e`).
3832 pub unavailable: Option<&'a str>,
3833 }
3834
3835 impl<'a> Choice<'a> {
3836 /// An option whose submitted value is also its label.
3837 #[must_use]
3838 pub const fn plain(value: &'a str) -> Self {
3839 Self::new(value, value)
3840 }
3841
3842 /// An option that submits one string and reads as another.
3843 ///
3844 /// A constructor rather than a literal, which is what `#[non_exhaustive]`
3845 /// costs and buys: outside this crate the struct cannot be built by naming
3846 /// its members, so every call site goes through here and the next member
3847 /// added breaks none of them.
3848 #[must_use]
3849 pub const fn new(value: &'a str, label: &'a str) -> Self {
3850 Self {
3851 value,
3852 label,
3853 unavailable: None,
3854 }
3855 }
3856
3857 /// The same option, not pickable yet, and why.
3858 ///
3859 /// Builder-shaped because the reason is the rare case: 39 of the 40 option
3860 /// sites measured across the tree do not have one.
3861 #[must_use]
3862 pub const fn unless(mut self, reason: &'a str) -> Self {
3863 self.unavailable = Some(reason);
3864 self
3865 }
3866
3867 /// Whether the option can be picked right now.
3868 ///
3869 /// The predicate a renderer branches on, so that "unavailable" is read as
3870 /// one condition in one place rather than as `unavailable.is_some()` at
3871 /// three renderers, one of which will invert it.
3872 #[must_use]
3873 pub const fn available(&self) -> bool {
3874 self.unavailable.is_none()
3875 }
3876 }
3877
3878 /// One entry in a field's suggestion list.
3879 ///
3880 /// A suggestion-only type rather than a fourth member on [`Choice`], ruled by
3881 /// Max 2026-08-21 (`1fcf2e9b`). The two are near-identical and that is the
3882 /// drift risk the ruling accepted, so the mitigation is written here: **an
3883 /// option and a candidate are submitted the same way and read differently.**
3884 /// An option is a thing you pick from a known set, and the set is the whole of
3885 /// what there is. A candidate is a thing you are being *oriented* toward out of
3886 /// a set nobody can see, which is why it carries [`detail`](Self::detail) and
3887 /// an option does not.
3888 ///
3889 /// This reverses a position quasi-router stated in its own doc, that a
3890 /// candidate is [`Choice`] "because a candidate is submitted under one string
3891 /// and read under another, which is what an option is". True and not
3892 /// sufficient: how a thing is submitted was never the half that differed.
3893 ///
3894 /// # Why the second string is not folded into the label
3895 ///
3896 /// Because every renderer wants it separately, and the two measured sites both
3897 /// draw it by hand today. The MNW server's tag box computes its context as the
3898 /// parent path -- "the parent path orients an otherwise ambiguous leaf:
3899 /// 'Format' appears under audio, software, writing, and video" -- and a list of
3900 /// four identical rows reading "Format" is not a usable list. In a webview the
3901 /// second string is styled differently, in a terminal it wants the remaining
3902 /// columns rather than a dash, and in neither is it part of what the typed
3903 /// value matches against. `Choice::new(slug, format!("{label} - {context}"))`
3904 /// loses all three of those facts, which is the condition this type exists to
3905 /// end.
3906 ///
3907 /// # No `unavailable`
3908 ///
3909 /// [`Choice::unavailable`] has no counterpart here, and the omission is the
3910 /// implementer's call recorded rather than an oversight. A suggestion that
3911 /// cannot be picked is arguably not a suggestion: an option list is a fixed set
3912 /// a user is owed an explanation about, and a candidate list is whatever a
3913 /// route decided to offer, so a route with nothing to say simply does not offer
3914 /// the row. Add it if a measured site ever wants it.
3915 ///
3916 /// # What it does not carry, and where that lives
3917 ///
3918 /// What *happens* when a candidate is picked. Picking is local by default -- it
3919 /// writes [`value`](Self::value) into the field that owns the list -- and a
3920 /// candidate that does something else says so with an action. An action is not
3921 /// a word this crate has, exactly as [`Field`] here has no `suggests` member,
3922 /// so both live on the router's owned mirror of this type. Ruled the same day
3923 /// (`ed1fa86f`).
3924 ///
3925 /// `#[non_exhaustive]` from birth. Non-negotiable and the reason is on the
3926 /// sibling: [`Choice`] took it at 0.28.0 only after `unavailable` broke 40
3927 /// literal sites in six repos, and a new type repeating that would be the third
3928 /// time the tree learned it.
3929 ///
3930 /// Added 0.35.0.
3931 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
3932 #[non_exhaustive]
3933 pub struct Candidate<'a> {
3934 /// What is submitted, and what picking writes into the field.
3935 pub value: &'a str,
3936 /// What is read.
3937 pub label: &'a str,
3938 /// The second line: what orients this candidate among rows that read alike.
3939 ///
3940 /// Optional because a candidate list whose labels are already distinct
3941 /// wants nothing here, and a renderer given [`None`] draws one line rather
3942 /// than an empty second one.
3943 pub detail: Option<&'a str>,
3944 }
3945
3946 impl<'a> Candidate<'a> {
3947 /// A candidate whose submitted value is also its label.
3948 #[must_use]
3949 pub const fn plain(value: &'a str) -> Self {
3950 Self::new(value, value)
3951 }
3952
3953 /// A candidate that submits one string and reads as another.
3954 ///
3955 /// A constructor rather than a literal, which is what `#[non_exhaustive]`
3956 /// costs and buys: outside this crate the struct cannot be built by naming
3957 /// its members, so every call site goes through here and the next member
3958 /// added breaks none of them.
3959 #[must_use]
3960 pub const fn new(value: &'a str, label: &'a str) -> Self {
3961 Self {
3962 value,
3963 label,
3964 detail: None,
3965 }
3966 }
3967
3968 /// The same candidate, with the line that tells it from its neighbours.
3969 #[must_use]
3970 pub const fn detailed(mut self, detail: &'a str) -> Self {
3971 self.detail = Some(detail);
3972 self
3973 }
3974 }
3975
3976 /// One field of a form.
3977 ///
3978 /// Borrowed rather than owned: a description is built, read once by a renderer,
3979 /// and dropped. Nothing here outlives the screen it describes.
3980 ///
3981 /// # What it carries, and what it does not
3982 ///
3983 /// Stated here so the next renderer does not re-ask, which is what the first
3984 /// two both did. It carries everything a renderer needs to *draw* the field:
3985 /// its kind, what it is called, what it is asked for, its standing help, what
3986 /// is wrong with it now, whether it is compulsory, whether it hides behind a
3987 /// disclosure, its ghost text, and the options it offers.
3988 ///
3989 /// It does not carry the **current value**, and it is not going to. That is the
3990 /// one thing here that is genuinely renderer state: a webview reads it back out
3991 /// of the DOM, an immediate-mode renderer holds a `&mut` to the app's own field
3992 /// and writes through it, and a terminal keeps an edit buffer. A description
3993 /// that carried the value would have to carry a way to write it back, at which
3994 /// point it is a form model and no longer a description.
3995 ///
3996 /// **Constraints** are here and enforcement is not, which is one line rather
3997 /// than two. [`required`], [`max_length`], [`min`] and [`max`] are facts about
3998 /// the *question*, so a renderer can emit its host's idiom for each — an HTML
3999 /// attribute, a marked label, a clamped spinner — and the platform helps the
4000 /// user before anything is submitted. Deciding that a value is wrong stays with
4001 /// whoever validated, and [`error`] is that decision arriving back.
4002 ///
4003 /// The set stops before `pattern`, and stops there on both tests at once. A
4004 /// regex has an honest answer in a webview and none anywhere else: egui would
4005 /// have to run it per keystroke and decide what a half-typed value means, which
4006 /// is enforcement wearing description's clothes. And it is one site in goingson
4007 /// and none in Balanced Breakfast, against 8 and 1 for `maxlength`. Measured
4008 /// 2026-08-09, `2cbad3e2`.
4009 ///
4010 /// [`error`]: Field::error
4011 /// [`required`]: Field::required
4012 /// [`max_length`]: Field::max_length
4013 /// [`min`]: Field::min
4014 /// [`max`]: Field::max
4015 /// How a slider's position becomes its value, and how finely it moves.
4016 ///
4017 /// **The data of a slider is a fraction and a function taking numbers to
4018 /// numbers.** Stated by Max 2026-08-21, and it corrects a reading this crate
4019 /// had carried since [`FieldKind::Range`] arrived at 0.28.0:
4020 /// [`min`](Field::min) and [`max`](Field::max) were never the control's extent.
4021 /// A slider's extent is always 0 to 1 — a thumb at 40% of a track — and the
4022 /// bounds are `f(0)` and `f(1)`. Linear is the constant-slope case, which is
4023 /// exactly why nobody noticed the function was there: when `f` is
4024 /// `min + t * (max - min)` the extent and the bounds coincide numerically and
4025 /// the mapping is invisible.
4026 ///
4027 /// So this is not a scale flag bolted onto a range. Every range described
4028 /// before it had a mapping, and four renderers each hard-coded the same one.
4029 ///
4030 /// # Why a closed family and not a function
4031 ///
4032 /// `fn(f64) -> f64` is the literal reading and it does not survive the
4033 /// description boundary. A fn pointer cannot be emitted into a browser, and it
4034 /// cannot be compared or hashed in a way that means anything, which this struct
4035 /// needs. A named family is the same semantics with arbitrary closures given
4036 /// up, and nothing measured wants one: the tree has a single non-linear shape
4037 /// across five controls and no second shape at all.
4038 ///
4039 /// # Why the step is here
4040 ///
4041 /// Max, in the same breath: if the family is prescriptive anyway, the step
4042 /// spacing belongs in it. On a slider the granularity and the mapping are one
4043 /// decision — a curve chosen without saying how finely it moves is half an
4044 /// answer — and holding them apart is what let a 0-to-1 threshold ship as a
4045 /// two-position control, since the host default of 1 was applied to a mapping
4046 /// nobody had named. It also un-overloads [`Field::step`], which stays as it
4047 /// was for a *typed* value, where there is no mapping and the granularity is a
4048 /// plain fact about the number.
4049 ///
4050 /// A future curve carrying a fact of its own — an exponent, an inflection —
4051 /// puts it in its own variant rather than on the struct, which is the second
4052 /// reason this shape is right.
4053 ///
4054 /// **The step is in the value's own units under every curve.** What a curve
4055 /// changes is the mapping, not the units the granularity is measured in: a step
4056 /// of `0.001` on an envelope time is three decimals whether the track is
4057 /// logarithmic or not, and a renderer that reads the step for display precision
4058 /// keeps reading it the same way.
4059 ///
4060 /// Added 0.32.0, from audiofiles' ADSR envelope and its storage cap picker.
4061 #[non_exhaustive]
4062 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4063 pub enum Curve<'a> {
4064 /// Constant slope: `f(t) = min + t * (max - min)`.
4065 ///
4066 /// What every described range meant before this enum existed, and the
4067 /// default, so a site that says nothing is correct unchanged.
4068 Linear {
4069 /// The granularity, in the value's own units. `None` is the host's own.
4070 step: Option<&'a str>,
4071 },
4072 /// Constant ratio: `f(t) = min * (max / min).powf(t)`.
4073 ///
4074 /// The mapping for a question whose extent spans orders of magnitude and
4075 /// whose interesting half is the small end. audiofiles' envelope times run
4076 /// 0.001 to 5 seconds, where a 5 ms attack and a 50 ms attack are audibly
4077 /// different instruments and a linear track puts both inside its first one
4078 /// percent.
4079 ///
4080 /// # It needs positive bounds
4081 ///
4082 /// A constant ratio is undefined across zero, so this asks for `min > 0`.
4083 /// A range that does not have that is mapped [`Linear`](Self::Linear)ly
4084 /// instead — see [`value_at`](Self::value_at). Stated rather than enforced,
4085 /// the way every other constraint in this crate is, and it is not a
4086 /// hypothetical: an envelope's sustain is a 0-to-1 level and is linear for
4087 /// this reason rather than by oversight.
4088 Logarithmic {
4089 /// The granularity, in the value's own units. `None` is the host's own.
4090 step: Option<&'a str>,
4091 },
4092 }
4093
4094 impl Default for Curve<'_> {
4095 fn default() -> Self {
4096 Self::Linear { step: None }
4097 }
4098 }
4099
4100 impl<'a> Curve<'a> {
4101 /// The granularity this curve moves in, whichever curve it is.
4102 ///
4103 /// Every variant carries one, so reading it does not need a match at each
4104 /// of the four renderers.
4105 #[must_use]
4106 pub const fn step(self) -> Option<&'a str> {
4107 // No wildcard: `#[non_exhaustive]` binds downstream, not here, so a
4108 // curve added later has to answer this rather than fall through to a
4109 // granularity nobody chose.
4110 match self {
4111 Self::Linear { step } | Self::Logarithmic { step } => step,
4112 }
4113 }
4114
4115 /// Whether this curve maps as a constant ratio *given these bounds*.
4116 ///
4117 /// The bounds are the argument because [`Logarithmic`](Self::Logarithmic)
4118 /// is a request rather than a guarantee: it needs `0 < min < max`, and a
4119 /// range that does not have that is drawn linearly. A renderer asks this
4120 /// instead of matching on the variant, so the fallback is decided in one
4121 /// place rather than four.
4122 #[must_use]
4123 pub fn is_ratio(self, min: f64, max: f64) -> bool {
4124 matches!(self, Self::Logarithmic { .. }) && min > 0.0 && max > min
4125 }
4126
4127 /// The value at a position along the track, where `position` is 0 to 1.
4128 ///
4129 /// `f`. The whole point of the type, and it lives here rather than in each
4130 /// renderer so that a terminal's bar, an egui slider and a browser's input
4131 /// cannot disagree about where a value sits.
4132 ///
4133 /// A position outside 0 to 1 is clamped, and bounds that are equal or
4134 /// inverted give `min` back: a track with no extent has one value on it.
4135 #[must_use]
4136 pub fn value_at(self, position: f64, min: f64, max: f64) -> f64 {
4137 let position = position.clamp(0.0, 1.0);
4138 // NaN named rather than fallen through: `max <= min` is false for a NaN
4139 // bound, so without it a track with no numbers on it would be mapped as
4140 // if it had two.
4141 if max <= min || min.is_nan() || max.is_nan() {
4142 return min;
4143 }
4144 if self.is_ratio(min, max) {
4145 min * (max / min).powf(position)
4146 } else {
4147 position.mul_add(max - min, min)
4148 }
4149 }
4150
4151 /// The position a value sits at, where the answer is 0 to 1.
4152 ///
4153 /// `f` inverted, which is what a renderer needs to *draw* a value it was
4154 /// handed. Same clamping and the same degenerate answer as
4155 /// [`value_at`](Self::value_at).
4156 #[must_use]
4157 pub fn position_of(self, value: f64, min: f64, max: f64) -> f64 {
4158 if max <= min || min.is_nan() || max.is_nan() {
4159 return 0.0;
4160 }
4161 let value = value.clamp(min, max);
4162 let position = if self.is_ratio(min, max) {
4163 (value / min).ln() / (max / min).ln()
4164 } else {
4165 (value - min) / (max - min)
4166 };
4167 position.clamp(0.0, 1.0)
4168 }
4169 }
4170
4171 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4172 pub struct Field<'a> {
4173 /// What kind of value it takes.
4174 pub kind: FieldKind,
4175 /// The name the value is submitted under.
4176 ///
4177 /// The *lower* end's name for a [`FieldKind::Interval`], whose upper end is
4178 /// [`upper_name`](Self::upper_name). Every other kind submits one value and
4179 /// this is the whole of it.
4180 pub name: &'a str,
4181 /// The name a [`FieldKind::Interval`]'s upper end is submitted under.
4182 ///
4183 /// [`None`] for every other kind, and sayable-and-ignored there the way
4184 /// [`options`](Self::options) is on a kind that offers none.
4185 ///
4186 /// Stated rather than derived from [`name`](Self::name), and
4187 /// [`FieldKind::Interval`] carries the measurement that decided it: the two
4188 /// sites in this tree disagree about affix order, so a derived rule would
4189 /// rename one of them. Which member a name sits in is also what says which
4190 /// end it is, so nothing separate carries the direction.
4191 ///
4192 /// An interval missing it is an interval with one end that can be submitted,
4193 /// which is a description a renderer may draw honestly and no better than
4194 /// that. [`Field::interval`] is what makes forgetting it unsayable, on the
4195 /// same footing as [`Field::range`] and its bounds.
4196 ///
4197 /// Added 0.34.0.
4198 pub upper_name: Option<&'a str>,
4199 /// What the user is asked for.
4200 pub label: &'a str,
4201 /// Standing help, shown whether or not anything is wrong.
4202 pub hint: Option<&'a str>,
4203 /// What is currently wrong with the value.
4204 pub error: Option<&'a str>,
4205 /// A consequence of the answer the user has given, carrying its own tone.
4206 ///
4207 /// The third message channel, between [`hint`](Self::hint) and
4208 /// [`error`](Self::error) and overlapping neither. A hint is standing help
4209 /// that does not depend on the value; an error says the value is not
4210 /// acceptable. A note is the case in the middle: the value is perfectly
4211 /// acceptable and choosing it costs something the user should know about.
4212 ///
4213 /// The first consumer is audiofiles' export Format field, where choosing
4214 /// WAV or AIFF over Original re-encodes and silently drops embedded BWF,
4215 /// iXML, loop points, cue markers and ID3. That is not a validation
4216 /// failure and it is not standing help — it is true of one answer to one
4217 /// question — and it was hand-drawn in the app's own draw callback for
4218 /// want of anywhere to say it.
4219 ///
4220 /// The tone is carried rather than fixed at [`Tone::Warning`] because the
4221 /// channel is not only for warnings: the same slot says "this is the
4222 /// recommended one" ([`Tone::Success`]) and "this is what that setting
4223 /// implies" ([`Tone::Info`]). A renderer gets the announcement behaviour
4224 /// off the tone for free — makeover-webview emits `data-tone` and treats
4225 /// Warning and Danger as assertive for `aria-live`.
4226 ///
4227 /// It does **not** make the field invalid. [`invalid`](Self::invalid) stays
4228 /// `error.is_some()`, so a note never marks the group as a problem.
4229 ///
4230 /// # Precedence, for a renderer with room for one
4231 ///
4232 /// Error, then note, then hint. A renderer that shows every message shows
4233 /// them in that order too. makeover-tui is the one with room for exactly
4234 /// one line, and it is why the order is decided here rather than three
4235 /// times: what is wrong outranks what it costs, which outranks how it
4236 /// works.
4237 ///
4238 /// Added 0.36.0.
4239 pub note: Option<(Tone, &'a str)>,
4240 /// Ghost text shown while the field is empty.
4241 ///
4242 /// User-facing text, and it sits with `label` and `hint` rather than with
4243 /// the value because it is a property of the *question* and not of the
4244 /// answer. It lived renderer-side in `makeover-webview` until 0.8.0 for one
4245 /// reason and it was not a reading on where it belonged: adding a field to
4246 /// a published struct is a breaking change.
4247 ///
4248 /// Not a substitute for a label. A field labelled only by its placeholder
4249 /// loses its label the moment anything is typed, and no renderer here can
4250 /// make that not happen, so the description keeps both.
4251 pub placeholder: Option<&'a str>,
4252 /// The options offered, in the order they are offered.
4253 ///
4254 /// Empty for every kind [`FieldKind::offers_options`] rejects. A field
4255 /// described with no options is sayable on purpose: it is what an app with
4256 /// an unfinished-loading option list actually has, and a renderer showing
4257 /// an empty control says so on screen rather than in a log.
4258 ///
4259 /// Which option is *current* is not here. That is the value, and the value
4260 /// is renderer state.
4261 pub options: &'a [Choice<'a>],
4262 /// What a file field takes, in the order a host offering the list shows it.
4263 ///
4264 /// Empty for every kind [`FieldKind::takes_files`] rejects, and empty is
4265 /// also a real answer for one that accepts it: a field that takes any file
4266 /// says so by listing nothing, which is what an `<input type="file">` with
4267 /// no `accept` does and what most of the measured sites are.
4268 ///
4269 /// It is a filter and it is the disclosure cue, and [`Accepted`]'s doc
4270 /// carries which reading is which. Nothing here validates: a host may hand
4271 /// back a file the list does not cover, exactly as a browser does when the
4272 /// user switches the picker to "All Files", and deciding a value is wrong
4273 /// stays with whoever validated.
4274 ///
4275 /// Added 0.31.0, `f7261a5a`.
4276 pub accept: &'a [Accepted<'a>],
4277 /// Whether more than one file may be picked at once.
4278 ///
4279 /// Only [`FieldKind::takes_files`] reads it. A multi-valued answer to any
4280 /// other question is a different shape — a set of options, a repeated
4281 /// group — and neither is this flag with a different kind beside it.
4282 ///
4283 /// False is the common case: 4 of the MNW server's 16 file inputs carry it.
4284 ///
4285 /// Added 0.31.0, `f7261a5a`.
4286 pub multiple: bool,
4287 /// Whether the form refuses to submit without it.
4288 pub required: bool,
4289 /// The longest the value may be, in characters.
4290 ///
4291 /// Added 0.11.0 with [`min`](Self::min) and [`max`](Self::max), joining
4292 /// [`required`](Self::required), which had been the only constraint here
4293 /// since before the crate wrote down that it carried none.
4294 pub max_length: Option<u32>,
4295 /// The lowest value accepted, as the host would write it.
4296 ///
4297 /// Text rather than a number, because the bound is only a number for some
4298 /// of the kinds that take one. goingson's own sites are `min="1"` on a
4299 /// duration and `min="2026-08-09T14:30"` on a datetime, and a numeric member
4300 /// could say the first and not the second. The [`kind`](Self::kind) already
4301 /// says how to read it, the same way it does for the value.
4302 pub min: Option<&'a str>,
4303 /// The highest value accepted, as the host would write it. See
4304 /// [`min`](Self::min).
4305 pub max: Option<&'a str>,
4306 /// The granularity the value moves in, as the host would write it.
4307 ///
4308 /// Text for [`min`](Self::min)'s reason, and it earns it twice over: the
4309 /// step of a date is a day and the step of a threshold is 0.01, and a
4310 /// numeric member could say one of them.
4311 ///
4312 /// Absent means the host's own granularity, which is the honest default
4313 /// rather than a missing value: a webview's `<input>` steps by 1 unless told
4314 /// otherwise, and that is the browser's rule and not this crate's to
4315 /// restate.
4316 ///
4317 /// # It is the granularity of a *typed* value
4318 ///
4319 /// [`FieldKind::Range`] reads its own from [`curve`](Self::curve) and
4320 /// ignores this, as of 0.32.0. Until then this member served both, and
4321 /// serving both is what the split fixes: on a slider the granularity and
4322 /// the mapping are one decision, and on a typed number there is no mapping
4323 /// to decide with. See [`Curve`], "Why the step is here".
4324 ///
4325 /// Added 0.28.0 with [`FieldKind::Range`], and narrowed away from it at
4326 /// 0.32.0.
4327 pub step: Option<&'a str>,
4328 /// How a slider's position becomes its value, and how finely it moves.
4329 ///
4330 /// [`FieldKind::Range`]'s, and nothing else reads it: a typed number has a
4331 /// granularity but no mapping, and takes [`step`](Self::step) instead.
4332 ///
4333 /// Defaults to [`Curve::Linear`] with no step, which is what every range
4334 /// described before 0.32.0 meant, so this member is additive and no
4335 /// existing site changes meaning.
4336 ///
4337 /// Added 0.32.0.
4338 pub curve: Curve<'a>,
4339 /// What the number is measured in: `s`, `ms`, `dB`, `GiB`.
4340 ///
4341 /// A fact about the value, not part of the question's name, and that
4342 /// distinction is the whole reason it is a member. The two readings come
4343 /// apart the moment anything reads a field back rather than drawing it: a
4344 /// [`max`](Self::max) of `-96` and a bound of `-96 dBFS` are the same number
4345 /// and not the same answer, and under the convention this replaces the unit
4346 /// could only be recovered by parsing it back out of a label.
4347 ///
4348 /// # Where a renderer draws it
4349 ///
4350 /// Beside the value, wherever that host puts a value. Not in the label: the
4351 /// label is the sentence above the control and that is the one place the
4352 /// convention could put it, which is why it read the same on every host and
4353 /// was wrong on the one host that had somewhere better. egui puts it inside
4354 /// the slider where the readout already is, a terminal appends it to the
4355 /// value in the edit line, a webview sets it adjacent to the input.
4356 ///
4357 /// # Which kinds read it
4358 ///
4359 /// [`FieldKind::measurable`] answers, and it is
4360 /// [`takes_files`](FieldKind::takes_files)'s footing: three renderers ask
4361 /// before they can decide whether to draw this, and a `matches!` per
4362 /// renderer is where the next measurable kind goes missing. A unit on a kind
4363 /// that rejects it is sayable and ignored, the same way
4364 /// [`options`](Self::options) is on a kind that offers none.
4365 ///
4366 /// # Why a string
4367 ///
4368 /// The measured sites are `GiB`, `dBFS`, `s` and `ms`. An enum would have to
4369 /// grow a member for every unit any consumer ever wants, and this crate does
4370 /// not know them; it knows that a number has one.
4371 ///
4372 /// Written as the symbol alone, with no brackets and no leading space. The
4373 /// spacing is the renderer's, because a slider's readout and a sentence want
4374 /// different answers.
4375 ///
4376 /// Added 0.33.0, `32215e21`, on eight sites across four files that had each
4377 /// arrived at "Attack (s)" separately.
4378 pub unit: Option<&'a str>,
4379 /// Whether the field lives behind a "more options" disclosure.
4380 pub extended: bool,
4381 }
4382
4383 impl<'a> Field<'a> {
4384 /// A plain required-nothing field of the given kind.
4385 #[must_use]
4386 pub const fn new(kind: FieldKind, name: &'a str, label: &'a str) -> Self {
4387 Self {
4388 kind,
4389 name,
4390 upper_name: None,
4391 label,
4392 hint: None,
4393 error: None,
4394 note: None,
4395 placeholder: None,
4396 options: &[],
4397 accept: &[],
4398 multiple: false,
4399 required: false,
4400 max_length: None,
4401 min: None,
4402 max: None,
4403 step: None,
4404 curve: Curve::Linear { step: None },
4405 unit: None,
4406 extended: false,
4407 }
4408 }
4409
4410 /// A bounded number the user drags across its whole extent.
4411 ///
4412 /// The third under-described kind, and it gets a constructor for
4413 /// [`select`](Self::select)'s reason: a range is the one kind whose bounds
4414 /// are not a rule but the control itself, so a call site that forgot them
4415 /// has a slider with nothing to slide across. Taking them as arguments is
4416 /// what makes that unsayable.
4417 ///
4418 /// The granularity stays a field rather than a fourth argument, and since
4419 /// 0.32.0 it is [`curve`](Self::curve)'s: it is genuinely optional — the
4420 /// host's own is a real answer — and the two bounds are not.
4421 #[must_use]
4422 pub const fn range(name: &'a str, label: &'a str, min: &'a str, max: &'a str) -> Self {
4423 Self {
4424 min: Some(min),
4425 max: Some(max),
4426 ..Self::new(FieldKind::Range, name, label)
4427 }
4428 }
4429
4430 /// One question with two ends, taking the name each end submits under.
4431 ///
4432 /// A constructor for [`range`](Self::range)'s reason inverted: a range's
4433 /// bounds are what a call site cannot forget, and an interval's second name
4434 /// is. An interval built through [`new`](Self::new) has an upper end with
4435 /// nowhere to be submitted, and nothing downstream can invent one, so taking
4436 /// it as an argument is what makes that unsayable.
4437 ///
4438 /// The extent, the granularity and the unit stay members. They describe the
4439 /// axis rather than either end and they are genuinely optional, which is
4440 /// [`FieldKind::Number`]'s arrangement and the one an interval takes.
4441 #[must_use]
4442 pub const fn interval(name: &'a str, upper_name: &'a str, label: &'a str) -> Self {
4443 Self {
4444 upper_name: Some(upper_name),
4445 ..Self::new(FieldKind::Interval, name, label)
4446 }
4447 }
4448
4449 /// A file field, taking the given accept list.
4450 ///
4451 /// The fourth under-described kind and it gets a constructor for
4452 /// [`range`](Self::range)'s reason rather than [`select`](Self::select)'s:
4453 /// a file field with no accept list is not broken, it is a field that takes
4454 /// anything, and the hazard is the opposite one. A call site that meant to
4455 /// restrict and forgot has a picker offering every file on the machine and
4456 /// a server refusing the upload afterwards, which is the failure the list
4457 /// exists to move forward. Taking it as an argument is what makes an
4458 /// accidental omission a deliberate `&[]`.
4459 ///
4460 /// [`multiple`](Self::multiple) stays a field. One file is the common case
4461 /// and the honest default; several is the thing worth saying.
4462 #[must_use]
4463 pub const fn upload(name: &'a str, label: &'a str, accept: &'a [Accepted<'a>]) -> Self {
4464 Self {
4465 accept,
4466 ..Self::new(FieldKind::File, name, label)
4467 }
4468 }
4469
4470 /// A select offering the given options.
4471 ///
4472 /// One of the two kinds under-described by [`Field::new`], so it gets a
4473 /// constructor rather than leaving every call site to remember that a
4474 /// select with an empty `options` renders as an empty select.
4475 #[must_use]
4476 pub const fn select(name: &'a str, label: &'a str, options: &'a [Choice<'a>]) -> Self {
4477 Self::offering(FieldKind::Select, name, label, options)
4478 }
4479
4480 /// A radio group offering the given options.
4481 ///
4482 /// The other. Same hazard as [`select`](Self::select) and a worse one: a
4483 /// radio group with no options draws nothing at all, so a call site that
4484 /// forgot them has an empty rectangle rather than a visibly empty control.
4485 #[must_use]
4486 pub const fn radio(name: &'a str, label: &'a str, options: &'a [Choice<'a>]) -> Self {
4487 Self::offering(FieldKind::Radio, name, label, options)
4488 }
4489
4490 /// The shared body of the two constructors that take options.
4491 ///
4492 /// Private, and keyed on the kind rather than exposed, because the two
4493 /// public names are the point: a call site says which question it is
4494 /// asking, not which flag it is setting.
4495 const fn offering(
4496 kind: FieldKind,
4497 name: &'a str,
4498 label: &'a str,
4499 options: &'a [Choice<'a>],
4500 ) -> Self {
4501 Self {
4502 options,
4503 ..Self::new(kind, name, label)
4504 }
4505 }
4506
4507 /// Whether the field is currently reporting a problem.
4508 ///
4509 /// Read this rather than testing `error.is_some()` at each renderer: the
4510 /// error state has to mark the field's whole group and not only the
4511 /// message, because a renderer with no descendant selectors (egui, a
4512 /// terminal) cannot find the group from the message. goingson already marks
4513 /// the group and Balanced Breakfast does not, so goingson's shape is the
4514 /// one taken here.
4515 ///
4516 /// [`note`](Self::note) is deliberately not consulted. A note says the
4517 /// answer costs something, not that it is unacceptable, and a field the
4518 /// user may submit as it stands is not invalid.
4519 #[must_use]
4520 pub const fn invalid(&self) -> bool {
4521 self.error.is_some()
4522 }
4523
4524 /// Whether the field carries both ends of its extent.
4525 ///
4526 /// Only [`FieldKind::Range`] owes them, and it owes them absolutely: a
4527 /// slider with one end missing has no extent to draw. Named here rather
4528 /// than left to each renderer to test `min.is_some() && max.is_some()`,
4529 /// which is three renderers arriving at the same condition and one of them
4530 /// getting it wrong, and named as a question about the *field* rather than
4531 /// about the kind because the kind cannot see the bounds.
4532 ///
4533 /// It is a check and not a guarantee. Nothing here refuses to build an
4534 /// unbounded range — [`Field::range`] is what makes the bounded one easy —
4535 /// so a renderer asks this and falls back to whatever its host does
4536 /// honestly with a number.
4537 #[must_use]
4538 pub const fn bounded(&self) -> bool {
4539 self.min.is_some() && self.max.is_some()
4540 }
4541
4542 /// Whether anything in [`accept`](Self::accept) names a media family.
4543 ///
4544 /// The question a renderer asks before it decides to keep room for a
4545 /// preview, and it is deliberately the *whole list* rather than one entry:
4546 /// the media dropzone this was measured against takes `image/*,video/*`, so
4547 /// there is no single family to return and there is still a disclosure to
4548 /// offer. Which one it turns out to be is known once a file is picked, which
4549 /// is renderer-side and after the description is gone.
4550 ///
4551 /// False for an empty list, for a list of suffixes, and for `text/csv`. A
4552 /// renderer that wants the family of a particular entry reads
4553 /// [`Accepted::family`].
4554 #[must_use]
4555 pub fn accepts_media(&self) -> bool {
4556 self.accept.iter().any(|one| one.family().is_some())
4557 }
4558 }
4559
4560 /// How much room a placement asks for.
4561 ///
4562 /// A column says it, and so does a [`Field`]. An intent, so the actual floor
4563 /// stays with `makeover-geometry`. goingson's task table spells these as
4564 /// `minmax(200px, 1fr)`, `140px` and content-sized; only the first three words
4565 /// of that survive deferral.
4566 /// `#[non_exhaustive]`, for the reason [`Fill`] and [`FieldKind`] are: a
4567 /// renderer matches on this and a vocabulary that grows must not break every
4568 /// renderer when it does.
4569 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4570 #[non_exhaustive]
4571 pub enum Width {
4572 /// Takes what it needs and no more.
4573 Content,
4574 /// A fixed share, the same at every width.
4575 Fixed,
4576 /// Absorbs whatever is left over.
4577 ///
4578 /// **Several fills divide what is left equally.** Stated because it would
4579 /// otherwise be undefined and each renderer would invent something, and
4580 /// stated this way because equal division is the only sharing rule that
4581 /// answers to "Any width, one answer" without a tiebreak: allocating in
4582 /// declaration order makes the result depend on the order the description
4583 /// was written in, which is a fact about the source file and not about the
4584 /// screen. It documents what both renderers already do — CSS grid gives
4585 /// `1fr 1fr`, ratatui gives each a `Constraint::Fill(1)` — rather than
4586 /// changing anything.
4587 ///
4588 /// So a row of fills is a legal thing to describe, and there is no rule
4589 /// against it. Measured 2026-08-16, every table in the tree uses exactly
4590 /// one, which is the discipline this would otherwise have had to forbid.
4591 Fill,
4592 }
4593
4594 /// What a member is worth when there is not room for all of them.
4595 ///
4596 /// Written for table columns and no longer only theirs. Three shapes ask the
4597 /// same question and this answers all three: a table too narrow for its
4598 /// columns, a row too narrow for its parts (see [`RowPart::priority`]), and a
4599 /// group of regions sharing one run of room -- goingson's tab strip and the
4600 /// [`Region::Band`] beside it, which is the case wiki `layout-room-and-fallback`
4601 /// was ruled on. It is what any member of a group is worth, not a table
4602 /// concept, and [`Fallback::Shed`] is what reads it.
4603 ///
4604 /// The doc below is the column argument, which is where the type was measured;
4605 /// the sentence that gave it away is [`Priority::Essential`]'s, which was
4606 /// already written about a row.
4607 ///
4608 /// Ordered: [`Priority::Optional`] drops first, [`Priority::Essential`] never
4609 /// drops. This replaces addressing columns by position, which is what both
4610 /// webview apps do today and is a live bug rather than only verbosity. goingson
4611 /// hides mobile columns with `nth-child(n+5)` against a seven-column table, so
4612 /// inserting a column silently hides the wrong one.
4613 /// `#[non_exhaustive]`, same reasoning as [`Width`]. Note the ordering is the
4614 /// whole point of the type, so a new tier has to be declared in its place in
4615 /// the sequence rather than appended.
4616 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
4617 #[non_exhaustive]
4618 pub enum Priority {
4619 /// Dropped first.
4620 Optional,
4621 /// Dropped once the optional members are gone.
4622 Secondary,
4623 /// Never dropped. Without it the group does not identify itself.
4624 Essential,
4625 }
4626
4627 /// How much room a group has, measured against its own allocation.
4628 ///
4629 /// Never authored. A renderer computes it from what the group was given and
4630 /// what the group's own contents ask for, in that renderer's units: a webview
4631 /// from `min-content` under a container query, a terminal from cell widths,
4632 /// egui from the galley. Nothing in the description says a number, which is the
4633 /// point -- an authored breakpoint rots and this cannot.
4634 ///
4635 /// # Why not [`Depth`]-style two members and no more
4636 ///
4637 /// Two is what the measurement supports. The goingson case that produced this
4638 /// type is a window 913px wide -- makeover-geometry's `SizeClass::Expanded` --
4639 /// holding a group that has run out of room. A third tier would be a guess
4640 /// about a shape nothing in the tree has yet.
4641 ///
4642 /// # Why it is not `SizeClass`
4643 ///
4644 /// Because 913 is exactly the case that proves they are different facts. The
4645 /// window is roomy and the group is not, so a type that answered for both would
4646 /// have to be wrong about one of them. Sharing the name would also invite
4647 /// `@media` thinking straight back in, which is what put a `position: absolute`
4648 /// in goingson's stylesheet in the first place. Container semantics instead: a
4649 /// group narrowed by a sidebar behaves the same as one narrowed by the window,
4650 /// and there is one code path rather than two.
4651 ///
4652 /// Ordered least room first, [`Priority`]'s convention, so a group nesting
4653 /// another takes the minimum of the two and relief still resolves inside-out.
4654 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
4655 #[non_exhaustive]
4656 pub enum Room {
4657 /// Not everything the group contains fits, and the group's [`Fallback`]
4658 /// decides what happens.
4659 Tight,
4660 /// Everything fits as described.
4661 Ample,
4662 }
4663
4664 /// What a group does when it is [`Room::Tight`].
4665 ///
4666 /// Authored, and required: the field carrying this has no `Default` and a group
4667 /// cannot be described without saying what it does when it runs out of room.
4668 /// Max ruled on that 2026-08-18 -- more intentionality from layout designers is
4669 /// acceptable so long as the constraints are solvable, because the goal is
4670 /// enabling good layouts rather than rescuing bad ones. A default here would be
4671 /// the crate guessing, and the guess would be silently wrong on the screens
4672 /// that matter.
4673 ///
4674 /// Relief resolves inside-out. A group asks its children to fall back before
4675 /// falling back itself, or an outer group collapses while an inner one still
4676 /// had slack.
4677 ///
4678 /// # No `Swap`
4679 ///
4680 /// An authored alternate group for the tight case is deliberately out of the
4681 /// first cut. It doubles the description for that group and the two halves can
4682 /// drift, which is the failure this vocabulary exists to end. Add it when a
4683 /// site proves it needs one.
4684 ///
4685 /// `#[non_exhaustive]`, [`Width`]'s reasoning. Unlike [`Priority`] there is no
4686 /// order to preserve, so a member can be appended.
4687 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4688 #[non_exhaustive]
4689 pub enum Fallback {
4690 /// One row becomes two. Every member stays, in the order described.
4691 Wrap,
4692 /// A row becomes a column. Every member stays, full width.
4693 Stack,
4694 /// Members drop by [`Priority`], down to [`Priority::Essential`].
4695 ///
4696 /// What a narrow table already does with its columns, applied to a group.
4697 /// What drops is gone from the screen, so this is right when the dropped
4698 /// members are facts the reader can do without and wrong when they are the
4699 /// only way to act.
4700 Shed,
4701 /// The members [`Shed`](Self::Shed) would drop move into one overflow
4702 /// control instead.
4703 ///
4704 /// The answer when a group holds actions. A control is not a fact: dropping
4705 /// it does not cost the reader a detail, it costs them the only way to act,
4706 /// which is [`RowPart::priority`]'s argument one level up.
4707 Menu,
4708 }
4709
4710 /// One column of a table.
4711 ///
4712 /// Described once. The grid track, the cell order and the drop behaviour are
4713 /// all derived from this, rather than being three hand-written encodings that
4714 /// must agree and are never checked against each other.
4715 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4716 pub struct Column<'a> {
4717 /// The heading, and the name the cell is addressed by.
4718 pub name: &'a str,
4719 /// How much room it asks for.
4720 pub width: Width,
4721 /// What it is worth when room runs out.
4722 pub priority: Priority,
4723 /// Whether the user can reorder the table by this column.
4724 ///
4725 /// `ce620871`. What reordering *calls* is not here — that is an address, and
4726 /// this crate names none — so a host pairs this with the route the way it
4727 /// pairs a row's parts with the row's activation. This says the affordance
4728 /// exists, which is what a renderer needs to draw a header a user can press
4729 /// rather than a heading they cannot.
4730 pub sortable: bool,
4731 /// Which way the table is ordered by this column, if it is.
4732 ///
4733 /// `None` on every column but the one in force. A renderer draws the caret
4734 /// from this and a webview sets `aria-sort`, which is why it is per column
4735 /// rather than a single fact on the table: the host idiom is a property of
4736 /// the header cell.
4737 ///
4738 /// Independent of [`sortable`](Self::sortable) rather than implied by it,
4739 /// because both combinations mean something. A column sorted and not
4740 /// sortable is a list ordered by a key the user cannot change, which is a
4741 /// real thing to describe and a caret worth drawing.
4742 pub sorted: Option<Sort>,
4743 }
4744
4745 /// Which way a column is ordered.
4746 ///
4747 /// Two, because there is no third. "Unsorted" is [`Column::sorted`] being
4748 /// `None`, and folding it in here would be the same absence said twice.
4749 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4750 pub enum Sort {
4751 /// Smallest, earliest or first alphabetically at the top.
4752 Ascending,
4753 /// The other way.
4754 Descending,
4755 }
4756
4757 impl Sort {
4758 /// The other direction, for a header that flips when pressed.
4759 #[must_use]
4760 pub const fn reversed(self) -> Self {
4761 match self {
4762 Self::Ascending => Self::Descending,
4763 Self::Descending => Self::Ascending,
4764 }
4765 }
4766
4767 /// What a webview writes into `aria-sort`.
4768 ///
4769 /// Named here rather than in the webview renderer because a terminal and an
4770 /// immediate-mode painter both want the same two words for a caret's label,
4771 /// and three renderers picking their own is the drift this crate ends.
4772 #[must_use]
4773 pub const fn as_str(self) -> &'static str {
4774 match self {
4775 Self::Ascending => "ascending",
4776 Self::Descending => "descending",
4777 }
4778 }
4779
4780 /// The caret a renderer draws for this direction.
4781 ///
4782 /// Here for [`as_str`](Self::as_str)'s reason, said about a glyph rather
4783 /// than a word: three renderers picking their own is the drift this crate
4784 /// ends. They had picked their own — two on the solid triangles and
4785 /// `makeover-webview` on the arrows U+2191/U+2193 — and agreeing by
4786 /// coincidence in three files is not agreement.
4787 ///
4788 /// Settled 2026-08-16 (Max): the solid triangles, U+25B2 and U+25BC. The
4789 /// reason generalizes past this pair and is the house rule now — prefer the
4790 /// bolder, simpler glyph over the thinner or more complicated one. A third
4791 /// spelling is not open for re-argument.
4792 ///
4793 /// **Bare, with no spacing.** Where the gap goes is each renderer's
4794 /// business: `makeover-tui` and `makeover-immediate` carry a leading space
4795 /// inside their `TableStyle` string and a webview emits its own in
4796 /// `content`, so folding a space in here would make one of the two wrong.
4797 ///
4798 /// Neither face the web apps self-host carries these — IBM Plex Mono has one
4799 /// glyph in the whole geometric-shapes block and Lato has none — so a
4800 /// browser falls back per glyph until the in-house face ships with them
4801 /// drawn in (makeover `6d6d9146`, wiki `typography-standard`). Cosmetic
4802 /// drift in one renderer, not a reason to spell it three ways.
4803 #[must_use]
4804 pub const fn glyph(self) -> &'static str {
4805 match self {
4806 Self::Ascending => "\u{25B2}",
4807 Self::Descending => "\u{25BC}",
4808 }
4809 }
4810 }
4811
4812 impl<'a> Column<'a> {
4813 /// A column that absorbs slack and drops after the optional ones.
4814 #[must_use]
4815 pub const fn new(name: &'a str) -> Self {
4816 Self {
4817 name,
4818 width: Width::Fill,
4819 priority: Priority::Secondary,
4820 sortable: false,
4821 sorted: None,
4822 }
4823 }
4824
4825 /// Whether this column survives at the given cutoff.
4826 ///
4827 /// A renderer narrows by raising the cutoff, and never by counting
4828 /// positions.
4829 #[must_use]
4830 pub const fn kept_at(&self, cutoff: Priority) -> bool {
4831 (self.priority as u8) >= (cutoff as u8)
4832 }
4833 }
4834
4835 /// What a table cell holds.
4836 ///
4837 /// [`RowPart`] for tables, and it exists for the same reason: a part that
4838 /// carries a control is not text, and a renderer with one class for the whole
4839 /// cell paints it as though it were. `makeover-webview` emitted a single
4840 /// `.cell` until 0.25.0, so a button in a cell inherited the cell's content
4841 /// colour, which is the exact drift [`RowPart::intent`] prevents for rows and
4842 /// prevented for nothing here.
4843 ///
4844 /// Four members, and the count is what quasi's `Cell` was measured to carry:
4845 /// a value, tokens (33 cells across 22 server templates), actions (30 rows
4846 /// carrying a control, 5 beside a value) and a link (35 cells across 18
4847 /// templates). Nothing was added past what something holds.
4848 ///
4849 /// `#[non_exhaustive]` for [`RowPart`]'s reason: growth here must not be a
4850 /// lockstep event across three renderers.
4851 ///
4852 /// # No hover-reveal
4853 ///
4854 /// [`RowPart`] carried a `revealed_on_hover` until 0.13.0 retired it, and this
4855 /// enum never gets one. A cell's actions are shown at rest in every consumer
4856 /// measured, and a member nothing uses is one three renderers owe an answer
4857 /// for.
4858 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4859 #[non_exhaustive]
4860 pub enum CellPart {
4861 /// The cell's own text.
4862 Value,
4863 /// Small labelled things in the cell: a status badge, a chip.
4864 Tokens,
4865 /// Controls that act on what the row is about.
4866 Actions,
4867 /// The cell's value, where the value is itself a link.
4868 Link,
4869 }
4870
4871 impl CellPart {
4872 /// The content intent the part takes.
4873 ///
4874 /// One part is text and three are not, so three answer with the intent
4875 /// inheriting already gives. That is [`RowPart::intent`]'s shape with the
4876 /// text side narrower: a cell's secondary and muted readings are the
4877 /// column's business, not the cell's.
4878 #[must_use]
4879 pub const fn intent(self) -> &'static str {
4880 match self {
4881 Self::Value => "content",
4882 // A token carries its own tone, and a part-level intent underneath
4883 // it would fight the token sitting on it.
4884 Self::Tokens => "content",
4885 // Actions carry controls rather than text.
4886 Self::Actions => "content",
4887 // A link takes the action colour from the control it is, rather
4888 // than the cell's text colour from the cell it sits in.
4889 Self::Link => "content",
4890 }
4891 }
4892 }
4893
4894 /// A named dimension a set can be narrowed by.
4895 ///
4896 /// One word for six things that were six mechanisms. MNW's discover page filters
4897 /// by free text, a flat any-of over item types, a tree of tags, a numeric range
4898 /// over price, a nested one-of over AI tier, and a browse position in the tag
4899 /// tree held separately from the tag selection — and the last two being separate
4900 /// is the whole reason a filter row there needs a tick box *and* a chevron. The
4901 /// panel is a mixed bag of hand-written controls because nothing named the thing
4902 /// they all are.
4903 ///
4904 /// Deliberately wider than that one page. audiofiles' library browser and
4905 /// goingson's filters are the same shape, and a word that only fitted discover
4906 /// would be discover's markup with a neutral name on it.
4907 ///
4908 /// # What it does not say
4909 ///
4910 /// **What picking a value calls.** This crate names no address, so a facet is
4911 /// paired with routes the way a column's [`sortable`](Column::sortable) flag is
4912 /// paired with what reordering calls.
4913 ///
4914 /// **How a tree is drawn.** Indented rows, a column of panes, a breadcrumb and a
4915 /// list: all four are honest renderings of the same described facet, and a
4916 /// terminal will not pick the same one a browser does. [`FacetValue::depth`] is
4917 /// what a renderer needs to draw any of them; the choice is not described.
4918 ///
4919 /// **Which values to show.** A tag tree has thousands of nodes and a panel shows
4920 /// a handful. Deciding which handful is the app's — it is the same question as
4921 /// which rows go in a table, and no table member answers it either.
4922 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4923 #[non_exhaustive]
4924 pub struct Facet<'a> {
4925 /// What the dimension is called, as the user reads it.
4926 pub name: &'a str,
4927 /// How many of its values may be in force, and in what shape.
4928 pub mode: Selecting,
4929 /// The values on offer, in the order they are drawn.
4930 ///
4931 /// A [`Selecting::Text`] facet has none: the value is whatever was typed,
4932 /// and a description that listed the possible strings would be listing the
4933 /// corpus. A [`Selecting::Range`] facet has none either, for the reason
4934 /// [`FieldKind::Range`] takes bounds rather than options — the ends are the
4935 /// question and the values between them are not enumerable.
4936 pub values: &'a [FacetValue<'a>],
4937 }
4938
4939 impl<'a> Facet<'a> {
4940 /// A dimension with values to pick from.
4941 #[must_use]
4942 pub const fn new(name: &'a str, mode: Selecting, values: &'a [FacetValue<'a>]) -> Self {
4943 Self { name, mode, values }
4944 }
4945
4946 /// Whether the facet is narrowing the set right now.
4947 ///
4948 /// The question a renderer asks to decide whether to offer a way out of it,
4949 /// and the reason it is derived rather than carried: a facet with nothing
4950 /// standing is unengaged by construction, so a member saying so could
4951 /// disagree with the values beside it. [`Standing::Inherited`] does not
4952 /// count — something further up is what is doing the narrowing, and clearing
4953 /// a child that was never picked clears nothing.
4954 ///
4955 /// Always false for [`Selecting::Text`] and [`Selecting::Range`], which
4956 /// carry no values. A host that wants a clear affordance on those knows
4957 /// whether its own box is empty; the description does not hold the typed
4958 /// string.
4959 #[must_use]
4960 pub fn engaged(&self) -> bool {
4961 self.values.iter().any(|value| value.standing.is_picked())
4962 }
4963
4964 /// The deepest value in the facet, or zero when it is flat.
4965 ///
4966 /// What an indenting renderer needs to reserve a gutter before it draws the
4967 /// first row, which is "First paint is final paint" applied to a tree: a
4968 /// gutter widened as deeper values arrive is the reflow that rule forbids.
4969 #[must_use]
4970 pub fn reach(&self) -> u8 {
4971 self.values
4972 .iter()
4973 .map(|value| value.depth)
4974 .max()
4975 .unwrap_or(0)
4976 }
4977 }
4978
4979 /// How many of a [`Facet`]'s values may be in force, and in what shape.
4980 ///
4981 /// Five, and the fifth is what made this an enum rather than a bool. `one-of`,
4982 /// `any-of`, a range and free text are the four a form vocabulary already has in
4983 /// [`FieldKind`]; a tree's selection is none of them, and describing tags as
4984 /// any-of was what forced browsing to be a second mechanism beside filtering.
4985 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
4986 #[non_exhaustive]
4987 pub enum Selecting {
4988 /// Exactly one value, and picking another replaces it.
4989 ///
4990 /// MNW's AI tier, whose three options are nested ranges rather than
4991 /// independent values, so two of them at once means nothing.
4992 OneOf,
4993 /// Any number of values, each independent of the others.
4994 AnyOf,
4995 /// A low end, a high end, or both.
4996 ///
4997 /// Carries no values for [`FieldKind::Range`]'s reason: the ends are the
4998 /// question.
4999 Range,
5000 /// Whatever the user types.
5001 Text,
5002 /// A position in a tree, edited by taking branches in and pruning branches
5003 /// out.
5004 ///
5005 /// The one mode that is not reducible to the others, and the one gesture
5006 /// that replaced two. Picking a value narrows the set to it *and* reveals
5007 /// its children, so browsing a tree and filtering by it stop being separate
5008 /// mechanisms with separate state. What a selection then is: a set of
5009 /// branches taken and a set pruned, resolved nearest-ancestor-first, so
5010 /// `music` in and `music/synths` out is sayable and no flat mode can say it.
5011 ///
5012 /// Resolution happens in the app, and what reaches a renderer is the
5013 /// [`Standing`] each drawn value ended up with. A renderer walking ancestors
5014 /// itself would be a renderer that can disagree with the results beside it.
5015 Subtree,
5016 }
5017
5018 impl Selecting {
5019 /// Whether the mode picks from values the description lists.
5020 ///
5021 /// False for [`Text`](Self::Text) and [`Range`](Self::Range), which are the
5022 /// two whose answer is not one of a set. A renderer asks this before it
5023 /// looks at [`Facet::values`], the way it asks
5024 /// [`FieldKind::offers_options`] before it looks at [`Field::options`].
5025 #[must_use]
5026 pub const fn offers_values(self) -> bool {
5027 matches!(self, Self::OneOf | Self::AnyOf | Self::Subtree)
5028 }
5029
5030 /// Whether a value can be pruned as well as picked.
5031 ///
5032 /// [`Subtree`](Self::Subtree) alone. Excluding a value from a flat facet is
5033 /// the same fact as not picking it, so an exclude affordance there would be
5034 /// a second control for a state the first one already holds.
5035 #[must_use]
5036 pub const fn prunes(self) -> bool {
5037 matches!(self, Self::Subtree)
5038 }
5039
5040 /// Whether picking a second value keeps the first.
5041 #[must_use]
5042 pub const fn accumulates(self) -> bool {
5043 matches!(self, Self::AnyOf | Self::Subtree)
5044 }
5045 }
5046
5047 /// One value a [`Facet`] offers, as it currently stands.
5048 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
5049 #[non_exhaustive]
5050 pub struct FacetValue<'a> {
5051 /// What identifies it, and what a host keys its route on.
5052 ///
5053 /// [`Choice::value`]'s split, and a tree is why it is not optional: two
5054 /// leaves under different parents are legitimately both called "Ambient",
5055 /// and the path is the only thing telling them apart. It is also what
5056 /// nearest-ancestor-wins resolves over, so an app that carried only labels
5057 /// could not compute the [`standing`](Self::standing) it hands back here.
5058 pub value: &'a str,
5059 /// What it is called, as the user reads it.
5060 ///
5061 /// The leaf's own name rather than its path: a facet drawn as an indented
5062 /// tree repeats every ancestor on every line otherwise, and one drawn as a
5063 /// breadcrumb has the ancestors already.
5064 pub label: &'a str,
5065 /// How many members of the set carry it.
5066 ///
5067 /// Optional, and settled that way rather than made mandatory: a count is a
5068 /// measured fact the app may not have. Counting a tag subtree under an
5069 /// active text search is a second query, and an app that will not pay for it
5070 /// should be able to describe the facet anyway rather than write a zero that
5071 /// reads as "none of them". That is [`Awaiting::amount`]'s rule in a second
5072 /// place — state a number when it was measured, and nothing when it was not.
5073 pub count: Option<u64>,
5074 /// Whether it is narrowing the set, and how it came to be.
5075 pub standing: Standing,
5076 /// How far down the tree it sits, counting from zero at the root.
5077 ///
5078 /// Always zero for a flat facet, which is what makes an indenting renderer
5079 /// one code path rather than two. A renderer that draws no tree at all still
5080 /// reads this, since a value's depth is what distinguishes two same-named
5081 /// leaves under different parents.
5082 pub depth: u8,
5083 /// Whether taking it reveals values under it.
5084 ///
5085 /// Distinct from having a nonzero [`depth`](Self::depth): a leaf deep in the
5086 /// tree branches no further, and a root with children does. Both facts are
5087 /// needed and neither implies the other, which is why the pair is two
5088 /// members rather than one count.
5089 pub branching: bool,
5090 }
5091
5092 impl<'a> FacetValue<'a> {
5093 /// An unpicked value at the root of the facet.
5094 #[must_use]
5095 pub const fn new(value: &'a str, label: &'a str) -> Self {
5096 Self {
5097 value,
5098 label,
5099 count: None,
5100 standing: Standing::Open,
5101 depth: 0,
5102 branching: false,
5103 }
5104 }
5105
5106 /// A value whose identifier is also what the user reads.
5107 ///
5108 /// [`Choice::of`]'s convenience, and it is the flat case: a type or a tier
5109 /// is its own name, and only a tree needs a path that is not one.
5110 #[must_use]
5111 pub const fn of(value: &'a str) -> Self {
5112 Self::new(value, value)
5113 }
5114
5115 /// How many members carry it, when that was measured.
5116 #[must_use]
5117 pub const fn counted(mut self, count: u64) -> Self {
5118 self.count = Some(count);
5119 self
5120 }
5121
5122 /// How it stands in the current selection.
5123 #[must_use]
5124 pub const fn standing(mut self, standing: Standing) -> Self {
5125 self.standing = standing;
5126 self
5127 }
5128
5129 /// Where it sits in the tree, and whether anything hangs off it.
5130 #[must_use]
5131 pub const fn at(mut self, depth: u8, branching: bool) -> Self {
5132 self.depth = depth;
5133 self.branching = branching;
5134 self
5135 }
5136 }
5137
5138 /// Whether a [`FacetValue`] is narrowing the set, and how it came to be.
5139 ///
5140 /// Four rather than a bool, and the two extra members are what a tree costs. A
5141 /// pruned branch and an untaken one are not the same state — one was decided
5142 /// against and the other was never reached — and a child under a taken parent is
5143 /// in force without anybody having picked it. A renderer given a bool either
5144 /// marks every descendant of a taken branch, which reads as forty deliberate
5145 /// choices, or marks none of them, which reads as unfiltered.
5146 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
5147 #[non_exhaustive]
5148 pub enum Standing {
5149 /// Not picked, and nothing above it is either.
5150 #[default]
5151 Open,
5152 /// Picked here. The set is narrowed to it and whatever hangs off it.
5153 Taken,
5154 /// In force because something above it was taken.
5155 Inherited,
5156 /// Pruned out, though something above it was taken.
5157 ///
5158 /// The state that only [`Selecting::Subtree`] can reach, and the reason
5159 /// exclusion is drawn as a visible affordance beside each label rather than
5160 /// as a modifier on the ordinary one: a gesture a terminal cannot express is
5161 /// a gesture half the renderers would have to leave out, and an affordance
5162 /// nothing teaches is one users do not find.
5163 Pruned,
5164 }
5165
5166 impl Standing {
5167 /// Whether the user decided this value, either way.
5168 ///
5169 /// True for [`Taken`](Self::Taken) and [`Pruned`](Self::Pruned) — both are
5170 /// choices, and both are things a "clear this" affordance has to clear.
5171 /// [`Inherited`](Self::Inherited) is not: clearing it clears nothing,
5172 /// because the decision is further up.
5173 #[must_use]
5174 pub const fn is_picked(self) -> bool {
5175 matches!(self, Self::Taken | Self::Pruned)
5176 }
5177
5178 /// Whether the value narrows the set in.
5179 ///
5180 /// [`Taken`](Self::Taken) and [`Inherited`](Self::Inherited): one was picked
5181 /// and one came down from above, and to the set they mean the same thing.
5182 /// The pair is named here so a renderer colouring in-force values does not
5183 /// have to know which is which.
5184 #[must_use]
5185 pub const fn in_force(self) -> bool {
5186 matches!(self, Self::Taken | Self::Inherited)
5187 }
5188
5189 /// The content intent the value takes.
5190 ///
5191 /// [`Pruned`](Self::Pruned) reads back a step, which is the three-tone rule
5192 /// above rather than a new decision: a pruned branch is still a live control
5193 /// — pressing it takes the prune off — so it may not wear `content-muted`,
5194 /// and it is not the thing itself either.
5195 #[must_use]
5196 pub const fn intent(self) -> &'static str {
5197 match self {
5198 Self::Taken | Self::Inherited | Self::Open => "content",
5199 Self::Pruned => "content-secondary",
5200 }
5201 }
5202 }
5203
5204 #[cfg(test)]
5205 mod tests {
5206 use super::*;
5207
5208 #[test]
5209 fn a_markdown_field_is_multiline_and_offers_nothing() {
5210 // The editing counterpart of markdown prose is still text: every host
5211 // can draw it, which is the whole reason the kind was addable.
5212 assert!(FieldKind::Rich.multiline());
5213 assert!(FieldKind::Textarea.multiline());
5214 assert!(!FieldKind::Text.multiline());
5215 // It is not a chooser and not a moment.
5216 assert!(!FieldKind::Rich.offers_options());
5217 assert!(!FieldKind::Rich.temporal());
5218 assert!(FieldKind::Rich.visible());
5219 }
5220
5221 #[test]
5222 fn only_the_numeric_kinds_are_measurable() {
5223 assert!(FieldKind::Number.measurable());
5224 assert!(FieldKind::Range.measurable());
5225 // An axis is measured in something and both its ends are in it, so the
5226 // unit is read once for the pair rather than per end.
5227 assert!(FieldKind::Interval.measurable());
5228 // A date is ordered and is not a quantity with a unit to choose: its
5229 // unit is fixed by the kind, so saying one would restate `kind`.
5230 for kind in [
5231 FieldKind::Text,
5232 FieldKind::Date,
5233 FieldKind::DateTime,
5234 FieldKind::Select,
5235 FieldKind::Checkbox,
5236 FieldKind::File,
5237 ] {
5238 assert!(!kind.measurable(), "{kind:?}");
5239 }
5240 }
5241
5242 #[test]
5243 fn a_field_carries_no_unit_until_one_is_given() {
5244 // Additive: absent is what every field described before 0.33.0 meant.
5245 let plain = Field::new(FieldKind::Number, "attack", "Attack");
5246 assert_eq!(plain.unit, None);
5247 let measured = Field {
5248 unit: Some("s"),
5249 ..Field::range("attack", "Attack", "0.001", "5")
5250 };
5251 assert_eq!(measured.unit, Some("s"));
5252 assert!(measured.kind.measurable());
5253 }
5254
5255 #[test]
5256 fn an_interval_states_both_ends_names() {
5257 // Stated rather than derived: the two measured sites disagree about
5258 // affix order, so a rule here would rename one of them.
5259 let suffixed = Field::interval("bpm_min", "bpm_max", "BPM");
5260 assert_eq!(suffixed.name, "bpm_min");
5261 assert_eq!(suffixed.upper_name, Some("bpm_max"));
5262 let prefixed = Field::interval("min_price", "max_price", "Price");
5263 assert_eq!(prefixed.name, "min_price");
5264 assert_eq!(prefixed.upper_name, Some("max_price"));
5265 assert_eq!(suffixed.kind, FieldKind::Interval);
5266 }
5267
5268 #[test]
5269 fn every_other_kind_has_no_upper_end() {
5270 // Additive: absent is what every field described before 0.34.0 meant.
5271 for kind in [FieldKind::Text, FieldKind::Number, FieldKind::Range] {
5272 assert_eq!(Field::new(kind, "n", "N").upper_name, None, "{kind:?}");
5273 }
5274 assert_eq!(Field::range("t", "T", "0", "1").upper_name, None);
5275 }
5276
5277 #[test]
5278 fn an_interval_owes_no_bounds_and_takes_the_axis_facts_once() {
5279 // A range's bounds are the control's extent and are owed; an interval's
5280 // are a rule on each end, which is Number's arrangement.
5281 let plain = Field::interval("bpm_min", "bpm_max", "BPM");
5282 assert!(!plain.bounded());
5283 let axis = Field {
5284 min: Some("0"),
5285 max: Some("300"),
5286 step: Some("1"),
5287 unit: Some("BPM"),
5288 ..Field::interval("bpm_min", "bpm_max", "BPM")
5289 };
5290 assert!(axis.bounded());
5291 assert_eq!(axis.unit, Some("BPM"));
5292 // Nothing here checks the crossing rule, exactly as nothing checks
5293 // `min` for a number: the description carries constraints and whoever
5294 // validated decides a value is wrong.
5295 assert!(axis.error.is_none());
5296 }
5297
5298 #[test]
5299 fn only_a_subtree_prunes_and_only_the_listing_modes_offer_values() {
5300 // Excluding a value from a flat facet is the same fact as not picking
5301 // it, so the affordance exists in exactly one mode.
5302 assert!(Selecting::Subtree.prunes());
5303 for mode in [
5304 Selecting::OneOf,
5305 Selecting::AnyOf,
5306 Selecting::Range,
5307 Selecting::Text,
5308 ] {
5309 assert!(!mode.prunes(), "{mode:?}");
5310 }
5311 // Text and Range answer with something that is not one of a set.
5312 assert!(!Selecting::Text.offers_values());
5313 assert!(!Selecting::Range.offers_values());
5314 assert!(Selecting::OneOf.offers_values());
5315 assert!(Selecting::AnyOf.accumulates());
5316 assert!(!Selecting::OneOf.accumulates());
5317 }
5318
5319 #[test]
5320 fn an_inherited_value_is_in_force_without_having_been_picked() {
5321 // The distinction a bool cannot hold, and the reason Standing has four
5322 // members: a child under a taken parent narrows the set, and clearing
5323 // it clears nothing.
5324 assert!(Standing::Inherited.in_force());
5325 assert!(!Standing::Inherited.is_picked());
5326 assert!(Standing::Taken.in_force());
5327 assert!(Standing::Taken.is_picked());
5328 // A prune is a decision that takes the value out.
5329 assert!(Standing::Pruned.is_picked());
5330 assert!(!Standing::Pruned.in_force());
5331 assert!(!Standing::Open.is_picked());
5332 assert!(!Standing::Open.in_force());
5333 // A pruned branch still answers a press, so it may not read as inert.
5334 assert_ne!(Standing::Pruned.intent(), "content-muted");
5335 }
5336
5337 #[test]
5338 fn a_facet_is_engaged_by_a_decision_and_not_by_an_inherited_value() {
5339 let inherited = [
5340 FacetValue::of("music")
5341 .standing(Standing::Taken)
5342 .at(0, true),
5343 FacetValue::new("music/synths", "synths")
5344 .standing(Standing::Inherited)
5345 .at(1, false),
5346 ];
5347 let facet = Facet::new("Tag", Selecting::Subtree, &inherited);
5348 assert!(facet.engaged());
5349 // The gutter an indenting renderer reserves before its first paint.
5350 assert_eq!(facet.reach(), 1);
5351
5352 let untouched = [
5353 FacetValue::of("music").at(0, true),
5354 FacetValue::new("music/synths", "synths")
5355 .standing(Standing::Inherited)
5356 .at(1, false),
5357 ];
5358 // Inherited alone is something further up doing the narrowing, and
5359 // there is nothing further up here.
5360 assert!(!Facet::new("Tag", Selecting::Subtree, &untouched).engaged());
5361
5362 // A text facet lists nothing, so it is flat and never reads as engaged
5363 // from its values: the typed string is not held here.
5364 let typed = Facet::new("Search", Selecting::Text, &[]);
5365 assert!(!typed.engaged());
5366 assert_eq!(typed.reach(), 0);
5367 }
5368
5369 #[test]
5370 fn a_count_is_absent_rather_than_zero_when_it_was_not_measured() {
5371 // Awaiting::amount's rule in a second place: a written zero reads as
5372 // "none of them", which is a different claim from "not counted".
5373 assert_eq!(FacetValue::of("Ambient").count, None);
5374 assert_eq!(FacetValue::of("Ambient").counted(0).count, Some(0));
5375 }
5376
5377 #[test]
5378 fn one_kind_takes_files_and_the_two_file_members_are_its_alone() {
5379 assert!(FieldKind::File.takes_files());
5380 for kind in [
5381 FieldKind::Text,
5382 FieldKind::Textarea,
5383 FieldKind::Rich,
5384 FieldKind::Select,
5385 FieldKind::Checkbox,
5386 FieldKind::Hidden,
5387 ] {
5388 assert!(!kind.takes_files());
5389 }
5390 // The default is a field that takes any one file, which is what an
5391 // input with no accept and no multiple already is.
5392 let plain = Field::new(FieldKind::File, "cover", "Cover");
5393 assert!(plain.accept.is_empty());
5394 assert!(!plain.multiple);
5395 }
5396
5397 #[test]
5398 fn an_accept_list_says_which_disclosure_and_a_suffix_says_none() {
5399 // The three shapes are the MNW server's own three, and the family is
5400 // the question a renderer asks before it keeps room for a preview.
5401 assert_eq!(
5402 Accepted::Family(Family::Image).family(),
5403 Some(Family::Image)
5404 );
5405 assert_eq!(Accepted::Type("image/jpeg").family(), Some(Family::Image));
5406 assert_eq!(Accepted::Type("audio/flac").family(), Some(Family::Audio));
5407 assert_eq!(
5408 Accepted::Type("video/quicktime").family(),
5409 Some(Family::Video)
5410 );
5411 // A media type outside the three families names none, and neither does
5412 // a suffix. `.mp3` is audio in fact and this crate will not infer it:
5413 // the table that said so would rot.
5414 assert_eq!(Accepted::Type("text/csv").family(), None);
5415 assert_eq!(Accepted::Suffix(".mp3").family(), None);
5416 assert_eq!(Accepted::Suffix(".tar.gz").family(), None);
5417 // Media types are case-insensitive and half the tree writes them
5418 // lowercase by habit rather than by rule.
5419 assert_eq!(Accepted::Type("IMAGE/PNG").family(), Some(Family::Image));
5420 }
5421
5422 #[test]
5423 fn every_accepted_entry_has_one_spelling_a_host_can_write() {
5424 assert_eq!(Accepted::Family(Family::Image).as_str(), "image/*");
5425 assert_eq!(Accepted::Family(Family::Audio).as_str(), "audio/*");
5426 assert_eq!(Accepted::Family(Family::Video).as_str(), "video/*");
5427 assert_eq!(Accepted::Type("text/csv").as_str(), "text/csv");
5428 assert_eq!(Accepted::Suffix(".tar.gz").as_str(), ".tar.gz");
5429 }
5430
5431 #[test]
5432 fn a_list_accepting_two_families_still_has_a_disclosure_to_offer() {
5433 // The measured dropzone: `accept="image/*,video/*"`. There is no single
5434 // family to return and there is still a preview to keep room for, which
5435 // is why the question is asked of the list rather than of one entry.
5436 const MEDIA: &[Accepted<'_>] = &[
5437 Accepted::Family(Family::Image),
5438 Accepted::Family(Family::Video),
5439 ];
5440 assert!(Field::upload("media", "Media", MEDIA).accepts_media());
5441 // An installer's suffix list wants no disclosure, which is the measured
5442 // case rather than a hypothetical one.
5443 const BUILDS: &[Accepted<'_>] = &[Accepted::Suffix(".zip"), Accepted::Suffix(".dmg")];
5444 assert!(!Field::upload("build", "Build", BUILDS).accepts_media());
5445 // And a field that takes anything says so by listing nothing.
5446 assert!(!Field::upload("any", "File", &[]).accepts_media());
5447 }
5448
5449 #[test]
5450 fn an_upload_carries_its_list_and_takes_one_file_until_it_says_otherwise() {
5451 const IMAGES: &[Accepted<'_>] = &[
5452 Accepted::Type("image/jpeg"),
5453 Accepted::Type("image/png"),
5454 Accepted::Type("image/webp"),
5455 ];
5456 let avatar = Field::upload("avatar", "Avatar", IMAGES);
5457 assert_eq!(avatar.kind, FieldKind::File);
5458 assert_eq!(avatar.accept, IMAGES);
5459 assert!(!avatar.multiple);
5460 let several = Field {
5461 multiple: true,
5462 ..avatar
5463 };
5464 assert!(several.multiple);
5465 }
5466
5467 #[test]
5468 fn the_four_readiness_states_are_one_axis_and_only_one_shows_content() {
5469 // Mutually exclusive is the test for one enum against several fields: a
5470 // region shows its content, or that it is coming, or that there is none,
5471 // or that it broke. Never two.
5472 assert!(Readiness::Ready.shows_content());
5473 for state in [Readiness::Pending, Readiness::Empty, Readiness::Failed] {
5474 assert!(!state.shows_content());
5475 }
5476 }
5477
5478 #[test]
5479 fn a_region_shows_all_of_its_children_unless_it_says_otherwise() {
5480 // The default is the behaviour every region had before this member
5481 // existed, which is what keeps it additive: a description written
5482 // against 0.22.0 says the same thing under 0.23.0.
5483 assert_eq!(Showing::default(), Showing::All);
5484 assert!(!Showing::All.selective());
5485 }
5486
5487 #[test]
5488 fn only_a_disclosure_can_show_nothing() {
5489 // The two derived idioms differ in one respect and this is it. A
5490 // carousel's row moves between frames and never reaches empty; a
5491 // disclosure's summary line is the same control wearing its closed
5492 // state, so a renderer has to know which it is drawing.
5493 assert!(Showing::AtMostOne.dismissible());
5494 assert!(!Showing::One.dismissible());
5495 assert!(!Showing::All.dismissible());
5496
5497 // Both are selective, though. Deriving chrome is one question and
5498 // whether that chrome closes is another.
5499 assert!(Showing::One.selective());
5500 assert!(Showing::AtMostOne.selective());
5501 }
5502
5503 #[test]
5504 fn an_empty_region_is_not_a_broken_one() {
5505 // An empty list is the normal state of a new install. Drawing it in a
5506 // danger tone reports a fault where there is none, and this is the one
5507 // place the distinction is carried.
5508 assert_eq!(Readiness::Empty.tone(), Tone::Neutral);
5509 assert_eq!(Readiness::Failed.tone(), Tone::Danger);
5510 assert_eq!(Readiness::Pending.tone(), Tone::Neutral);
5511 }
5512
5513 #[test]
5514 fn a_column_can_be_sorted_without_being_sortable() {
5515 // Both combinations mean something, which is why the two fields are
5516 // independent rather than one implying the other. A list ordered by a
5517 // key the user cannot change is a real thing with a caret worth drawing.
5518 let fixed = Column {
5519 sorted: Some(Sort::Descending),
5520 ..Column::new("Created")
5521 };
5522
5523 assert!(!fixed.sortable);
5524 assert_eq!(fixed.sorted.map(Sort::as_str), Some("descending"));
5525
5526 let offered = Column {
5527 sortable: true,
5528 ..Column::new("Name")
5529 };
5530 assert_eq!(offered.sorted, None);
5531 }
5532
5533 #[test]
5534 fn a_direction_flips_and_says_what_it_is() {
5535 assert_eq!(Sort::Ascending.reversed(), Sort::Descending);
5536 assert_eq!(Sort::Descending.reversed().reversed(), Sort::Descending);
5537 assert_eq!(Sort::Ascending.as_str(), "ascending");
5538 }
5539
5540 #[test]
5541 fn a_direction_carries_its_caret_and_the_two_are_not_the_same_glyph() {
5542 // The spelling every renderer reads, so that agreeing is composition
5543 // rather than three files happening to hold the same literal.
5544 assert_eq!(Sort::Ascending.glyph(), "\u{25B2}");
5545 assert_eq!(Sort::Descending.glyph(), "\u{25BC}");
5546 assert_ne!(Sort::Ascending.glyph(), Sort::Descending.glyph());
5547 // Bare. The gap is the renderer's, and a space here would be a second
5548 // one wherever a renderer already carries its own.
5549 for d in [Sort::Ascending, Sort::Descending] {
5550 assert_eq!(d.glyph().trim(), d.glyph());
5551 }
5552 }
5553
5554 #[test]
5555 fn a_figure_carries_its_tone_because_no_renderer_can_derive_it() {
5556 // Three of goingson's five sites tone the figure by their own means, so
5557 // tone is carried at every site that needs it and derived at none. The
5558 // same reasoning `Meter` reached, from a different direction.
5559 let streak = Figure::new("0", "Current Streak").tone(Tone::Warning);
5560 assert_eq!(streak.tone, Tone::Warning);
5561 assert_eq!(Figure::new("17", "Total").tone, Tone::Neutral);
5562 }
5563
5564 #[test]
5565 fn a_figures_change_is_the_toned_part_and_is_absent_by_default() {
5566 // 0.13.0. The MNW server's stat card is a label, a value and a delta,
5567 // across four screens, and the delta is what reads as good or bad. Tone
5568 // had no consumer before this: the figure itself is an ordinary fact.
5569 let views = Figure::new("1,204", "Views")
5570 .change("+12.5%")
5571 .tone(Tone::Success);
5572 assert_eq!(views.change, Some("+12.5%"));
5573 assert_eq!(views.tone, Tone::Success);
5574
5575 // A figure with nothing to compare against says so by having no change,
5576 // rather than by carrying an empty string a renderer has to test for.
5577 assert_eq!(Figure::new("3.1%", "Conversion").change, None);
5578 }
5579
5580 #[test]
5581 fn a_figures_value_is_text_because_only_the_app_knows_what_it_is() {
5582 // "84%", "12/30", "3d". A figure is whatever the app computed, already
5583 // formatted, and that is the line between this and `Meter`: a meter is
5584 // a proportion a renderer draws, a figure is a fact it sets in type.
5585 for value in ["84%", "12/30", "3d"] {
5586 assert_eq!(Figure::new(value, "Rate").value, value);
5587 }
5588 }
5589
5590 #[test]
5591 fn a_proportion_is_a_row_part_and_takes_no_intent_of_its_own() {
5592 // The meter carries the tone, so a part-level intent underneath would
5593 // fight it. Same answer `Tokens` needed, for the same reason.
5594 assert_eq!(RowPart::Proportion.intent(), RowPart::Tokens.intent());
5595 }
5596
5597 #[test]
5598 fn a_file_field_is_drawn_and_offers_no_options() {
5599 // It is a control the user operates, unlike `Hidden`, and it does not
5600 // pick from a list the description carries, unlike `Select`.
5601 assert!(FieldKind::File.visible());
5602 assert!(!FieldKind::File.offers_options());
5603 assert!(!FieldKind::File.confidential());
5604 }
5605
5606 #[test]
5607 fn a_constraint_is_a_fact_about_the_question_and_not_a_verdict() {
5608 // The whole model: the description carries the rule, the renderer emits
5609 // its host's idiom, and `error` is what arrives back when someone
5610 // validated. Nothing here decides a value is wrong.
5611 let field = Field {
5612 max_length: Some(100),
5613 min: Some("1"),
5614 max: Some("240"),
5615 required: true,
5616 ..Field::new(FieldKind::Number, "minutes", "Minutes")
5617 };
5618 assert!(!field.invalid());
5619
5620 // A bound is text because it is only a number for some of the kinds
5621 // that take one. goingson has both shapes live.
5622 let when = Field {
5623 min: Some("2026-08-09T14:30"),
5624 ..Field::new(FieldKind::Text, "starts", "Starts")
5625 };
5626 assert_eq!(when.min, Some("2026-08-09T14:30"));
5627 }
5628
5629 #[test]
5630 fn a_meter_keeps_the_over_run_the_percentage_throws_away() {
5631 // The whole reason this is a pair. goingson's `Task::time_progress`
5632 // clamps to 100 and then carries `is_over_estimate` beside it to say
5633 // what the clamp dropped; a meter says both from one fact.
5634 let over = Meter::new(45, 30);
5635 assert_eq!(over.percent(), 100);
5636 assert!(over.overflowing());
5637
5638 let exact = Meter::new(30, 30);
5639 assert_eq!(exact.percent(), over.percent());
5640 assert!(!exact.overflowing());
5641 }
5642
5643 #[test]
5644 fn an_empty_set_does_not_divide_by_zero() {
5645 // Sayable on purpose, so it has to be answerable. A meter over an
5646 // unloaded count is what an app actually has for a frame.
5647 let none = Meter::new(0, 0);
5648 assert_eq!(none.percent(), 0);
5649 assert!(none.is_empty());
5650 assert!(!none.overflowing());
5651 }
5652
5653 #[test]
5654 fn the_ratio_survives_where_a_percentage_would_not() {
5655 // Given 43 nothing can recover "3 of 7", which is why the numbers are
5656 // carried and the label names only the noun.
5657 let m = Meter::new(3, 7).label("subtasks");
5658 assert_eq!(m.percent(), 42);
5659 assert_eq!((m.done, m.total), (3, 7));
5660 assert_eq!(m.label, Some("subtasks"));
5661 }
5662
5663 #[test]
5664 fn tone_is_carried_because_no_renderer_can_derive_it() {
5665 // The same fullness means opposite things on two of goingson's bars,
5666 // and only the app knows which.
5667 let subtasks = Meter::new(9, 10).tone(Tone::Success);
5668 let estimate = Meter::new(9, 10).tone(Tone::Danger);
5669 assert_eq!(subtasks.percent(), estimate.percent());
5670 assert_ne!(subtasks.tone, estimate.tone);
5671 // Untoned by default: a bar says nothing about status until something
5672 // says so, the same way a row is not selectable until told.
5673 assert_eq!(Meter::new(9, 10).tone, Tone::Neutral);
5674 }
5675
5676 #[test]
5677 fn an_act_is_reachable_until_it_is_disabled() {
5678 // The one member a renderer must branch on, and since 0.19.0 the only
5679 // member there is. A stated state is not by itself a reason to stop
5680 // answering, which is the distinction `State` makes and every
5681 // hand-rolled button in the tree had to remember.
5682 assert!(!Act::new("Save").disabled());
5683 assert!(Act::new("Save").state(State::Disabled).disabled());
5684 }
5685
5686 #[test]
5687 fn an_act_carries_its_key_because_a_terminal_has_nothing_else() {
5688 // No key is the ordinary case, and the webview hosts that ignore it
5689 // are why it stayed optional.
5690 assert_eq!(Act::new("Delete").key, None);
5691 let quit = Act::new("Quit").key("q").tone(Tone::Danger);
5692 assert_eq!(quit.key, Some("q"));
5693 assert_eq!(quit.tone, Tone::Danger);
5694 }
5695
5696 #[test]
5697 fn a_meter_does_not_overflow_on_large_counts() {
5698 // done * 100 in u32 would wrap somewhere past 42 million. Counts that
5699 // size are not tasks, but a description layer that silently reports 3%
5700 // for a full bar is worse than one that is slow.
5701 let big = Meter::new(u32::MAX, u32::MAX);
5702 assert_eq!(big.percent(), 100);
5703 assert!(!big.overflowing());
5704 }
5705
5706 #[test]
5707 fn inset_is_raised_with_the_light_moved() {
5708 let (rl, rd) = Bevel::Raised.edges();
5709 let (il, id) = Bevel::Inset.edges();
5710 assert_eq!((rl, rd), (Edge::Light, Edge::Dark));
5711 assert_eq!((il, id), (rd, rl));
5712 }
5713
5714 #[test]
5715 fn pressing_twice_is_a_no_op() {
5716 for b in [Bevel::Raised, Bevel::Inset] {
5717 assert_eq!(b.pressed().pressed(), b);
5718 }
5719 }
5720
5721 #[test]
5722 fn a_raised_region_is_never_filled_with_a_recessed_surface() {
5723 // The bug this vocabulary exists to make unrepresentable.
5724 assert_eq!(Depth::Raised.fill(), Some(Fill::Raised));
5725 assert_eq!(Depth::Raised.bevel(), Some(Bevel::Raised));
5726 assert_eq!(Depth::Well.bevel(), Some(Bevel::Inset));
5727 assert_ne!(Depth::Well.fill(), Depth::Raised.fill());
5728 }
5729
5730 #[test]
5731 fn state_is_orthogonal_to_depth() {
5732 // The reason State is its own axis and not a Depth member: a disabled
5733 // button and a disabled field are both disabled and are not the same
5734 // shape, which one shared variant could not have said.
5735 assert_eq!(Depth::Raised.fill(), Some(Fill::Raised));
5736 assert_eq!(Depth::Well.fill(), Some(Fill::Well));
5737 assert!(State::Disabled.suppresses_interaction());
5738 }
5739
5740 #[test]
5741 fn only_disabled_stops_answering() {
5742 // Kept in spirit from the version where `Focus` was the counter-example:
5743 // suppressing interaction is `Disabled`'s alone, so a member added here
5744 // later does not get to inherit it by being a state.
5745 assert!(State::Disabled.suppresses_interaction());
5746 }
5747
5748 #[test]
5749 fn disabled_resolves_against_an_intent_makeover_already_derives() {
5750 // No new token, so this costs no `makeover` release.
5751 assert_eq!(State::Disabled.token(), "content-muted");
5752 }
5753
5754 #[test]
5755 fn flat_has_neither_edge_nor_fill() {
5756 assert_eq!(Depth::Flat.bevel(), None);
5757 assert_eq!(Depth::Flat.fill(), None);
5758 }
5759
5760 #[test]
5761 fn sunken_is_recessed_by_colour_with_no_edge() {
5762 // The one member carrying a fill without a bevel. A renderer that
5763 // assumes the two arrive together drops the fill silently, which is
5764 // exactly what makeover-webview did before 0.3.0.
5765 assert_eq!(Depth::Sunken.fill(), Some(Fill::Sunken));
5766 assert_eq!(Depth::Sunken.bevel(), None);
5767 }
5768
5769 #[test]
5770 fn sunken_and_flat_are_different_claims() {
5771 // Both edgeless, and only one of them needs a colour. Collapsing them
5772 // is what left an unchosen tab unsayable.
5773 assert_eq!(Depth::Flat.bevel(), Depth::Sunken.bevel());
5774 assert_ne!(Depth::Flat.fill(), Depth::Sunken.fill());
5775 }
5776
5777 #[test]
5778 fn a_sunken_surface_is_not_a_well() {
5779 // Authored in opposite directions: makeover derives surface-well by
5780 // inverting against the theme's content colour, while surface-sunken is
5781 // authored and may sit darker than raised.
5782 assert_ne!(Fill::Sunken, Fill::Well);
5783 assert_eq!(Fill::Sunken.token(), "surface-sunken");
5784 assert_eq!(Fill::Well.token(), "surface-well");
5785 }
5786
5787 #[test]
5788 fn every_selector_describes_both_of_its_states() {
5789 // The gap 0.3.0 closed. Before it, only `chosen` existed and the
5790 // unchosen option fell through to Flat at every renderer.
5791 for s in [Selector::Tabs, Selector::Segmented, Selector::Toggle] {
5792 assert_ne!(
5793 s.chosen(),
5794 s.unchosen(),
5795 "{s:?} cannot tell picked from unpicked"
5796 );
5797 }
5798 }
5799
5800 #[test]
5801 fn only_a_tab_inverts_the_other_way() {
5802 // Tabs recede so the chosen one comes forward; a segment and a toggle
5803 // stand up so the chosen one is held in. That inversion is the whole
5804 // content of "picked" once colour is deferred, and it is why the three
5805 // are not one member with a flag.
5806 assert_eq!(Selector::Tabs.unchosen(), Depth::Sunken);
5807 assert_eq!(Selector::Tabs.chosen(), Depth::Raised);
5808
5809 for s in [Selector::Segmented, Selector::Toggle] {
5810 assert_eq!(s.unchosen(), Depth::Raised);
5811 assert_eq!(s.chosen(), Depth::Well);
5812 // Held in is what pressing produces: one appearance, two reasons.
5813 assert_eq!(s.unchosen().pressed(), s.chosen());
5814 }
5815 }
5816
5817 #[test]
5818 fn pressing_a_card_makes_a_well() {
5819 assert_eq!(Depth::Raised.pressed(), Depth::Well);
5820 assert_eq!(
5821 Depth::Raised.pressed().bevel(),
5822 Depth::Raised.bevel().map(Bevel::pressed)
5823 );
5824 // Only raised regions respond to being pressed.
5825 assert_eq!(Depth::Flat.pressed(), Depth::Flat);
5826 assert_eq!(Depth::Well.pressed(), Depth::Well);
5827 // An overlay is a surface, not a control.
5828 assert_eq!(Depth::Overlay.pressed(), Depth::Overlay);
5829 }
5830
5831 #[test]
5832 fn an_overlay_is_lifted_rather_than_edged() {
5833 // The wave-2 rule: a surface over the page takes elevation, a surface
5834 // in the page takes a bevel. Both halves come off the one Depth, so
5835 // they cannot disagree.
5836 assert_eq!(Depth::Overlay.fill(), Some(Fill::Overlay));
5837 assert_eq!(Depth::Overlay.bevel(), None);
5838
5839 // Three depths have no bevel and they are not the same claim. Flat has
5840 // nothing to separate from, Sunken's colour is doing the separating,
5841 // and an overlay is separated by the lift.
5842 assert_ne!(Depth::Overlay.fill(), Depth::Sunken.fill());
5843 assert_ne!(Depth::Overlay.fill(), Depth::Flat.fill());
5844 }
5845
5846 #[test]
5847 fn a_note_is_neither_a_hint_nor_an_error() {
5848 // audiofiles' export Format field: choosing WAV over Original
5849 // re-encodes and drops the embedded metadata. Perfectly valid, and it
5850 // costs something.
5851 let format = Field {
5852 note: Some((Tone::Warning, "Re-encoding drops embedded BWF and iXML")),
5853 ..Field::select("format", "Format", &[])
5854 };
5855 assert!(!format.invalid(), "a note is not a validation failure");
5856 assert!(format.hint.is_none());
5857 assert!(format.error.is_none());
5858 assert_eq!(format.note.unwrap().0, Tone::Warning);
5859
5860 // The default is no note, so the 15 in-tree `..Field::new(..)`
5861 // literals absorb the member with no call-site edit.
5862 assert!(Field::new(FieldKind::Text, "title", "Title").note.is_none());
5863 }
5864
5865 #[test]
5866 fn neutral_is_content_not_muted_content() {
5867 // Neutral means "no status", and that is all it means. It answered
5868 // `content-muted` until 2026-08-27, which muted a figure's headline
5869 // number to the colour of its own caption. What makes a badge quiet
5870 // is `Token::Badge` answering no click, which lives on the renderer.
5871 assert_eq!(Tone::Neutral.token(), "content");
5872 assert!(!Token::Badge.interactive());
5873 assert_eq!(State::Disabled.token(), "content-muted");
5874 }
5875
5876 #[test]
5877 fn intents_name_makeover_tokens_and_nothing_else() {
5878 assert_eq!(Edge::Light.token(), "bevel-light");
5879 assert_eq!(Edge::Dark.token(), "bevel-dark");
5880 assert_eq!(Fill::Raised.token(), "surface-raised");
5881 assert_eq!(Fill::Well.token(), "surface-well");
5882 // No value ever leaves this crate.
5883 for t in [
5884 Edge::Light.token(),
5885 Edge::Dark.token(),
5886 Tone::Danger.token(),
5887 Tone::Neutral.token(),
5888 State::Disabled.token(),
5889 ] {
5890 assert!(!t.starts_with('#'), "{t} looks like a value");
5891 assert!(
5892 !t.chars().next().unwrap().is_ascii_digit(),
5893 "{t} is a value"
5894 );
5895 }
5896 }
5897
5898 #[test]
5899 fn a_badge_cannot_be_pressed_and_a_chip_latches() {
5900 // The one line that runs through all three apps' taxonomies.
5901 assert!(!Token::Badge.interactive());
5902 assert!(Token::Chip { removable: false }.interactive());
5903 assert!(Token::Chip { removable: true }.interactive());
5904
5905 // A badge is a label, so giving it an edge would lie about it.
5906 assert_eq!(Token::Badge.depth(false), Depth::Flat);
5907 assert_eq!(Token::Badge.depth(true), Depth::Flat);
5908
5909 // A latched chip wears the same shape a pressed one does.
5910 let chip = Token::Chip { removable: false };
5911 assert_eq!(chip.depth(false), Depth::Raised);
5912 assert_eq!(chip.depth(true), Depth::Raised.pressed());
5913 }
5914
5915 #[test]
5916 fn a_toast_and_a_banner_differ_in_more_than_placement() {
5917 assert!(Notice::Toast.transient());
5918 assert!(!Notice::Banner.transient());
5919 // A toast floats above the page; a banner rests in the flow.
5920 assert_eq!(Notice::Toast.fill(), Fill::Overlay);
5921 assert_eq!(Notice::Banner.fill(), Fill::Raised);
5922 }
5923
5924 #[test]
5925 fn emphasis_falls_off_down_the_row() {
5926 // `revealed_on_hover` was asserted here until 0.13.0 retired it. It said
5927 // a row's actions stay hidden until hover, which stopped being true when
5928 // makeover-webview 0.23.0 showed them at rest, and nothing had consumed
5929 // it for a release either way.
5930 assert_eq!(RowPart::Primary.intent(), "content");
5931 assert_eq!(RowPart::Secondary.intent(), "content-secondary");
5932 assert_eq!(RowPart::Meta.intent(), "content-muted");
5933 }
5934
5935 #[test]
5936 fn a_token_part_carries_no_intent_of_its_own() {
5937 // Each token carries its own tone, so a part-level intent underneath
5938 // would fight the thing sitting on it. Same reasoning as actions, which
5939 // is why they answer alike.
5940 assert_eq!(RowPart::Tokens.intent(), RowPart::Actions.intent());
5941 assert_eq!(RowPart::Tokens.intent(), "content");
5942 }
5943
5944 #[test]
5945 fn the_two_temporal_kinds_are_the_two_that_name_a_moment() {
5946 // The pair is named once so a host with parsing to do asks here rather
5947 // than spelling it out, which is `offers_options`' reason.
5948 assert!(FieldKind::Date.temporal());
5949 assert!(FieldKind::DateTime.temporal());
5950
5951 for kind in [
5952 FieldKind::Text,
5953 FieldKind::Secret,
5954 FieldKind::Number,
5955 FieldKind::Email,
5956 FieldKind::Url,
5957 FieldKind::Tel,
5958 FieldKind::Range,
5959 FieldKind::Textarea,
5960 FieldKind::Rich,
5961 FieldKind::Select,
5962 FieldKind::Radio,
5963 FieldKind::Checkbox,
5964 FieldKind::File,
5965 FieldKind::Hidden,
5966 ] {
5967 assert!(!kind.temporal(), "{kind:?}");
5968 }
5969 }
5970
5971 #[test]
5972 fn a_date_carries_no_time_and_a_datetime_carries_no_zone() {
5973 // The formats are the whole reason the members are worth naming apart
5974 // from text, so the doc comments and the constants have to agree. A
5975 // host reading one and meeting the other is the silent failure.
5976 assert_eq!(DATE_FORMAT, "%Y-%m-%d");
5977 assert!(!DATE_FORMAT.contains("%H"), "a day carries no hour");
5978
5979 assert_eq!(DATETIME_FORMAT, "%Y-%m-%dT%H:%M");
5980 assert!(
5981 DATETIME_FORMAT.starts_with(DATE_FORMAT),
5982 "a moment starts with the day it is on"
5983 );
5984 // Local, and that is a property of the value rather than an omission.
5985 assert!(!DATETIME_FORMAT.contains("%Z"), "no zone name");
5986 assert!(!DATETIME_FORMAT.ends_with('Z'), "not UTC-stamped");
5987 assert!(!DATETIME_FORMAT.contains("%S"), "no seconds by default");
5988 }
5989
5990 #[test]
5991 fn a_temporal_kind_takes_a_label_above_it_and_offers_no_options() {
5992 // Neither is a checkbox and neither is a fixed set, so both fall where
5993 // text does. Asserted because a new kind lands in three predicates and
5994 // only one of them is the interesting one.
5995 for kind in [FieldKind::Date, FieldKind::DateTime] {
5996 assert!(kind.visible(), "{kind:?}");
5997 assert!(!kind.confidential(), "{kind:?}");
5998 assert!(!kind.labels_itself(), "{kind:?}");
5999 assert!(!kind.offers_options(), "{kind:?}");
6000 }
6001 }
6002
6003 #[test]
6004 fn a_cell_part_names_an_intent_and_only_the_value_is_text() {
6005 // The table half of what RowPart::intent does for rows. A cell holding
6006 // a control and a cell holding text answered alike until 0.14.0, and a
6007 // control in a cell took the cell's text colour.
6008 assert_eq!(CellPart::Value.intent(), "content");
6009
6010 for part in [CellPart::Tokens, CellPart::Actions, CellPart::Link] {
6011 // Each for its own reason -- a token carries its tone, an action is
6012 // a control, a link takes the action colour -- and all three reach
6013 // the intent inheriting already gives.
6014 assert_eq!(part.intent(), CellPart::Value.intent(), "{part:?}");
6015 }
6016 }
6017
6018 #[test]
6019 fn every_cell_part_answers_with_a_token_and_never_a_value() {
6020 for part in [
6021 CellPart::Value,
6022 CellPart::Tokens,
6023 CellPart::Actions,
6024 CellPart::Link,
6025 ] {
6026 let intent = part.intent();
6027 assert!(!intent.is_empty(), "{part:?} names nothing");
6028 assert!(!intent.starts_with('#'), "{part:?} looks like a value");
6029 }
6030 }
6031
6032 #[test]
6033 fn a_separator_is_what_tells_a_section_from_a_subsection() {
6034 assert!(Heading::Section.separated());
6035 assert!(!Heading::Subsection.separated());
6036 assert!(!Heading::Page.separated());
6037 }
6038
6039 #[test]
6040 fn a_chosen_segment_is_held_in_and_a_chosen_tab_comes_forward() {
6041 assert_eq!(Selector::Segmented.chosen(), Depth::Well);
6042 assert_eq!(Selector::Toggle.chosen(), Depth::Well);
6043 // The exception, and the whole folder semantic: the open tab joins its
6044 // pane rather than sinking away from it.
6045 assert_eq!(Selector::Tabs.chosen(), Depth::Raised);
6046
6047 // A held-in segment is indistinguishable from a pressed raised one,
6048 // which is the economy the light model buys over a colour swap.
6049 assert_eq!(Selector::Segmented.chosen(), Depth::Raised.pressed());
6050
6051 // A toggle stands alone; the other two are built out of parts that
6052 // touch.
6053 assert!(Selector::Segmented.abutting());
6054 assert!(Selector::Tabs.abutting());
6055 assert!(!Selector::Toggle.abutting());
6056 }
6057
6058 #[test]
6059 fn columns_are_peers_and_a_split_is_not() {
6060 // The distinction the member exists for. A split's two panes stand in a
6061 // master-detail relationship; columns choose nothing about each other.
6062 // Both are flat, so depth cannot tell them apart and the doc has to.
6063 assert_eq!(Region::Columns.depth(), Depth::Flat);
6064 assert_eq!(Region::Split.depth(), Depth::Flat);
6065 assert_ne!(Region::Columns, Region::Split);
6066 }
6067
6068 #[test]
6069 fn columns_carry_no_count_and_no_share() {
6070 // The two things a board is always asked to carry and must not. How
6071 // many is what the children say; how wide is settled by "peers are
6072 // equal".
6073 //
6074 // The guard is the binding itself and it is a compile-time one: adding
6075 // a field to `Columns` stops this line compiling, which is a better
6076 // failure than any assertion about it. Written out rather than inlined
6077 // for exactly that reason.
6078 let columns: Region<'_> = Region::Columns;
6079 assert_eq!(columns.name(), None);
6080 }
6081
6082 #[test]
6083 fn columns_are_described_and_the_escape_hatch_is_still_one_member() {
6084 // A board's contents are ordinary description all the way down, so a
6085 // renderer that does not lay them across still draws every column.
6086 // Stacking them vertically is honouring this member, not degrading it.
6087 assert!(Region::Columns.described());
6088 assert!(!Region::Bespoke { name: "timeline" }.described());
6089 }
6090
6091 #[test]
6092 fn a_span_never_has_zero_minutes_however_it_is_asked_for() {
6093 // Every renderer divides by this. A caller passing a backwards or empty
6094 // span is a bug, but it is not a bug worth a panic three renderers deep.
6095 assert_eq!(Span::new(600, 600).length(), 1);
6096 assert_eq!(Span::new(600, 300).length(), 1);
6097 assert_eq!(Span::DAY.length(), 1440);
6098 }
6099
6100 #[test]
6101 fn a_span_can_run_past_midnight_without_a_second_date() {
6102 // 22:00 to 02:00. The alternative was carrying a date, which drags a
6103 // timezone into the vocabulary for the sake of one night shift.
6104 let overnight = Span::new(1320, 1560);
6105 assert_eq!(overnight.length(), 240);
6106 assert!(overnight.holds(1500));
6107 assert!(!overnight.holds(1200));
6108 }
6109
6110 #[test]
6111 fn overlap_is_computed_rather_than_declared() {
6112 // The reason Placement carries no `conflicts` flag: the times already
6113 // say it, and a second source for one fact is how a stale conflict
6114 // badge outlives the conflict.
6115 let morning = Placement::new(540, 60); // 09:00-10:00
6116 let overlapping = Placement::new(570, 60); // 09:30-10:30
6117 let after = Placement::new(600, 60); // 10:00-11:00
6118
6119 assert!(morning.overlaps(overlapping));
6120 assert!(overlapping.overlaps(morning), "overlap is symmetric");
6121 // Touching end to end is not overlapping: `to` is exclusive, so a
6122 // 10:00 start does not collide with a 10:00 end.
6123 assert!(!morning.overlaps(after));
6124 assert!(!after.overlaps(morning));
6125 }
6126
6127 #[test]
6128 fn a_placement_is_always_drawable() {
6129 assert_eq!(Placement::new(540, 0).length(), 1);
6130 assert_eq!(Placement::new(540, 30).end(), 570);
6131 }
6132
6133 #[test]
6134 fn a_track_places_the_fraction_every_renderer_would_otherwise_compute() {
6135 let day = Track::DAY;
6136 assert!((day.fraction(0) - 0.0).abs() < f32::EPSILON);
6137 assert!((day.fraction(720) - 0.5).abs() < f32::EPSILON);
6138 // Clamped rather than off the end: an event running past the span's
6139 // close draws at the edge, which beats panicking or drawing nowhere.
6140 assert!((day.fraction(2000) - 1.0).abs() < f32::EPSILON);
6141 }
6142
6143 #[test]
6144 fn a_track_counts_its_slots_and_never_divides_by_zero() {
6145 assert_eq!(Track::DAY.slots(), 96);
6146 assert_eq!(Track::over(Span::new(540, 1020)).slots(), 32);
6147 // A span that does not divide evenly keeps a slot for its tail.
6148 assert_eq!(Track::over(Span::new(0, 50)).slots(), 4);
6149 // slot: 0 is a caller bug that reads as one slot, not a panic.
6150 let degenerate = Track {
6151 span: Span::DAY,
6152 slot: 0,
6153 tick: 60,
6154 unit: Unit::Minutes,
6155 };
6156 assert_eq!(degenerate.slots(), 1);
6157 }
6158
6159 #[test]
6160 fn a_track_carries_facts_and_no_presentation() {
6161 // The guard on the thing the withdrawn refusal was right about. If a
6162 // pixel measure, a scroll offset or a colour ever lands on Track, the
6163 // member has stopped being a fact about the data and the timeline
6164 // really has become a component library wearing a description's name.
6165 let day = Track::DAY;
6166 assert_eq!(day.span, Span::DAY);
6167 assert_eq!(day.slot, 15);
6168 assert_eq!(day.tick, 60);
6169 assert_eq!(day.unit, Unit::Minutes);
6170
6171 // Three fields when this was written, and the fourth came here to say
6172 // why, which is the whole point of the assertion. `unit` is what the
6173 // integers COUNT -- a fact about the data, unavailable from the numbers
6174 // themselves, and the absence of it is what let a month strip render
6175 // under a wall clock. A fifth field still has to argue, and "the
6176 // renderer would find it handy" is still not the argument.
6177 // Destructured rather than rebuilt: this is the form that names every
6178 // field and stops compiling when a fifth arrives, without binding
6179 // anything a lint has to forgive.
6180 let Track {
6181 span: _,
6182 slot: _,
6183 tick: _,
6184 unit: _,
6185 } = day;
6186 }
6187
6188 #[test]
6189 fn a_day_strip_is_the_same_arithmetic_under_a_different_unit() {
6190 // The probe that found the defect, kept as a test. Fifteen days from
6191 // day three, on a thirty-one day month: the geometry was always right
6192 // and only the label was wrong, which is why `unit` is a fact and not
6193 // presentation.
6194 let march = Track::days(Span::new(0, 31));
6195 assert_eq!(march.slots(), 31);
6196 assert_eq!(march.unit, Unit::Days);
6197
6198 let leave = Placement::new(2, 15);
6199 assert!((march.fraction(leave.at()) - 2.0 / 31.0).abs() < 0.0001);
6200 assert!((march.fraction(leave.end()) - 17.0 / 31.0).abs() < 0.0001);
6201 }
6202
6203 #[test]
6204 fn a_pane_is_looked_into_and_a_band_is_not() {
6205 assert_eq!(Region::Pane.depth(), Depth::Well);
6206 assert_eq!(Region::Modal.depth(), Depth::Raised);
6207 for r in [
6208 Region::Band,
6209 Region::Sidebar,
6210 Region::Group,
6211 Region::Split,
6212 Region::TabGroup,
6213 ] {
6214 assert_eq!(r.depth(), Depth::Flat, "{r:?} should carry no edge");
6215 }
6216 }
6217
6218 #[test]
6219 fn exactly_one_region_is_opaque() {
6220 // The escape hatch is one member and stays one member. If a second
6221 // undescribed region ever appears, the description has started
6222 // conceding rather than deferring.
6223 for r in [
6224 Region::Band,
6225 Region::Sidebar,
6226 Region::Pane,
6227 Region::Group,
6228 Region::Split,
6229 Region::TabGroup,
6230 Region::Modal,
6231 // A widget is described, and that is the whole of what separates it
6232 // from a bespoke here. Both carry a name this crate never reads;
6233 // only one of them has contents under it that a renderer which does
6234 // not know the name can still walk.
6235 Region::Widget { name: "carousel" },
6236 ] {
6237 assert!(r.described(), "{r:?} should be describable");
6238 }
6239 assert!(!Region::Bespoke { name: "day-plan" }.described());
6240 }
6241
6242 #[test]
6243 fn a_picture_that_says_nothing_is_a_claim_and_not_an_oversight() {
6244 // The distinction a renderer with no graphics protocol runs on: draw
6245 // the words, or draw nothing. Standing in for a decorative rule with
6246 // the word "decoration" is worse than leaving the space empty.
6247 assert!(Image::new("The library view, mid-import").speaks());
6248 assert!(!Image::new("").speaks());
6249 }
6250
6251 #[test]
6252 fn a_caption_and_alt_text_are_not_the_same_line() {
6253 // A caption is content everybody reads; alt text stands in for the
6254 // picture. A screenshot with a caption still needs alt text.
6255 let shot = Image::new("A file list with three rows selected").caption("The library view");
6256 assert_eq!(shot.caption, Some("The library view"));
6257 assert!(shot.speaks());
6258 assert_ne!(shot.alt, shot.caption.unwrap());
6259 }
6260
6261 #[test]
6262 fn a_picture_can_say_how_much_room_to_hold() {
6263 // The whole point: a renderer reserves from the ratio, so the space is
6264 // right at any width. A fixed height would only be right at one.
6265 let shot = Image::new("a screenshot").intrinsic(5120, 3412);
6266 let e = shot.intrinsic.expect("carried");
6267 assert_eq!((e.width, e.height), (5120, 3412));
6268 assert!((e.ratio().unwrap() - 1.5006).abs() < 0.001);
6269 }
6270
6271 #[test]
6272 fn a_picture_with_no_dimensions_reserves_nothing_rather_than_guessing() {
6273 // `None` is honest: a creator upload whose size was never recorded does
6274 // not know it. A renderer must not invent one.
6275 assert_eq!(Image::new("unknown upload").intrinsic, None);
6276 assert_eq!(Extent::new(0, 10).ratio(), None);
6277 assert_eq!(Extent::new(10, 0).ratio(), None);
6278 }
6279
6280 #[test]
6281 fn a_picture_is_wanted_now_unless_the_app_says_otherwise() {
6282 // Eager is the safe default and lazy is the opt-in, because deferring
6283 // something already on screen saves nothing and moves its shift later.
6284 assert_eq!(Image::new("hero").loading, Loading::Eager);
6285 assert_eq!(Loading::default(), Loading::Eager);
6286 assert_eq!(Image::new("frame 2").lazy().loading, Loading::Lazy);
6287 }
6288
6289 #[test]
6290 fn a_picture_keeps_its_own_proportions_unless_told_otherwise() {
6291 // The default is the one that shows the whole picture at its own shape,
6292 // so a renderer ignoring Fit entirely is still right about the common
6293 // case. The shipped MNW carousel sets no object-fit at all, which is
6294 // this.
6295 assert_eq!(Image::new("a").fit, Fit::Natural);
6296 assert_eq!(Fit::default(), Fit::Natural);
6297 assert_eq!(Image::new("a").fit(Fit::Cover).fit, Fit::Cover);
6298 }
6299
6300 #[test]
6301 fn a_group_contains_a_section_without_claiming_to_be_a_pane() {
6302 // The whole of why this is a member rather than a `Pane`. A pane is
6303 // looked into and scrolls; a group is neither, and four groups inside a
6304 // settings pane described as panes are four wells inside a well.
6305 assert_eq!(Region::Pane.depth(), Depth::Well);
6306 assert_eq!(Region::Group.depth(), Depth::Flat);
6307 assert_ne!(Region::Group, Region::Pane);
6308
6309 // Described, and it carries no name: a group is a primitive every
6310 // renderer draws from scratch, which is what separates it from the two
6311 // members that do carry one.
6312 assert!(Region::Group.described());
6313 assert_eq!(Region::Group.name(), None);
6314 }
6315
6316 #[test]
6317 fn a_section_heading_names_a_block_that_now_exists() {
6318 // `Heading::Section` has said "names a block within the screen" since
6319 // 0.2.0 and there was no block. The pairing is the point, and it is the
6320 // reason a group carries no heading of its own: the heading is an
6321 // ordinary node in the body, and a group without one is legal.
6322 assert!(Heading::Section.separated());
6323 assert_eq!(Region::Group.depth(), Depth::Flat);
6324 }
6325
6326 #[test]
6327 fn a_widget_inherits_its_depth_the_way_a_bespoke_does() {
6328 // Stronger than the bespoke case: a widget is drawn by whichever
6329 // renderer recognises the name, so a depth chosen here would be this
6330 // crate deciding a carousel is raised on every host.
6331 assert_eq!(Region::Widget { name: "carousel" }.depth(), Depth::Flat);
6332 assert_eq!(Region::Widget { name: "pager" }.depth(), Depth::Flat);
6333 }
6334
6335 #[test]
6336 fn a_name_is_readable_without_asking_which_member_carried_it() {
6337 // A renderer dispatching on a name wants the string, not the member.
6338 // Writing that `matches!` at each renderer is how the two drift apart.
6339 assert_eq!(Region::Widget { name: "carousel" }.name(), Some("carousel"));
6340 assert_eq!(
6341 Region::Bespoke { name: "day-plan" }.name(),
6342 Some("day-plan")
6343 );
6344
6345 for r in [
6346 Region::Band,
6347 Region::Sidebar,
6348 Region::Pane,
6349 Region::Group,
6350 Region::Split,
6351 Region::TabGroup,
6352 Region::Modal,
6353 ] {
6354 assert_eq!(r.name(), None, "{r:?} names nothing an app chose");
6355 }
6356 }
6357
6358 #[test]
6359 fn a_bespoke_region_inherits_its_depth_rather_than_choosing_one() {
6360 // The app owns the contents, not the placement. An app that wants its
6361 // timeline in a well frames it in a Pane.
6362 assert_eq!(Region::Bespoke { name: "day-plan" }.depth(), Depth::Flat);
6363 assert_eq!(Region::Bespoke { name: "kanban" }.depth(), Depth::Flat);
6364 }
6365
6366 #[test]
6367 fn a_screen_with_a_bespoke_region_is_still_a_whole_screen() {
6368 // The argument the member exists for: goingson's day-plan has to be
6369 // routable, or the description covers only the boring screens and the
6370 // interesting four need a second path beside the router.
6371 let day_plan = [
6372 Region::Band,
6373 Region::Bespoke { name: "day-plan" },
6374 Region::Sidebar,
6375 ];
6376 assert_eq!(day_plan.iter().filter(|r| r.described()).count(), 2);
6377 assert_eq!(day_plan.iter().filter(|r| !r.described()).count(), 1);
6378 }
6379
6380 #[test]
6381 fn a_secret_field_is_marked_as_one_and_a_hidden_field_is_not_drawn() {
6382 let secret = Field::new(FieldKind::Secret, "password", "Password");
6383 assert!(secret.kind.confidential());
6384 assert!(secret.kind.visible());
6385
6386 assert!(!FieldKind::Hidden.visible());
6387 // Nothing else is confidential, or the marker means nothing.
6388 for k in [
6389 FieldKind::Text,
6390 FieldKind::Number,
6391 FieldKind::Textarea,
6392 FieldKind::Rich,
6393 FieldKind::Select,
6394 FieldKind::Checkbox,
6395 FieldKind::Hidden,
6396 ] {
6397 assert!(!k.confidential(), "{k:?} should not be confidential");
6398 }
6399
6400 // Only a checkbox carries its own label.
6401 assert!(FieldKind::Checkbox.labels_itself());
6402 assert!(!FieldKind::Text.labels_itself());
6403 }
6404
6405 #[test]
6406 fn a_plain_field_offers_nothing_and_a_select_offers_its_options() {
6407 let text = Field::new(FieldKind::Text, "title", "Title");
6408 assert!(text.options.is_empty());
6409 assert_eq!(text.placeholder, None);
6410
6411 let sizes = [Choice::plain("small"), Choice::plain("large")];
6412 let select = Field::select("size", "Size", &sizes);
6413 assert_eq!(select.kind, FieldKind::Select);
6414 assert_eq!(select.options.len(), 2);
6415 }
6416
6417 #[test]
6418 fn a_choice_says_what_submits_and_what_is_read_apart() {
6419 // The whole reason it is two strings. `plain` is the case where they
6420 // coincide, and it is a shorthand rather than the general shape.
6421 let plain = Choice::plain("7");
6422 assert_eq!((plain.value, plain.label), ("7", "7"));
6423
6424 let spelled = Choice::new("7", "One week");
6425 assert_ne!(spelled.value, spelled.label);
6426 assert!(
6427 spelled.available(),
6428 "an option is pickable until it says not"
6429 );
6430 }
6431
6432 #[test]
6433 fn a_candidate_carries_the_line_that_tells_it_from_its_neighbours() {
6434 // The gap this type was born for: two candidates whose labels read
6435 // alike, told apart by the second string and by nothing else. The
6436 // measured site is the MNW tag box, where "Format" is a leaf under
6437 // audio, software, writing and video.
6438 let audio = Candidate::new("audio/format", "Format").detailed("Audio");
6439 let writing = Candidate::new("writing/format", "Format").detailed("Writing");
6440
6441 assert_eq!(audio.label, writing.label);
6442 assert_ne!(audio.detail, writing.detail);
6443 assert_ne!(
6444 audio, writing,
6445 "two rows a user cannot tell apart are two rows the type can"
6446 );
6447 }
6448
6449 #[test]
6450 fn a_candidate_is_read_differently_from_an_option_and_written_the_same() {
6451 // The ruling's own distinction, held as a test so the two types do not
6452 // drift back together. Submitting is identical; the second line is the
6453 // whole of what differs, and it is absent by default because a list of
6454 // distinct labels wants nothing there.
6455 let candidate = Candidate::plain("rust");
6456 assert_eq!((candidate.value, candidate.label), ("rust", "rust"));
6457 assert_eq!(
6458 candidate.detail, None,
6459 "one line unless the route says otherwise"
6460 );
6461
6462 let option = Choice::plain("rust");
6463 assert_eq!(
6464 (candidate.value, candidate.label),
6465 (option.value, option.label)
6466 );
6467 }
6468
6469 #[test]
6470 fn a_radio_asks_the_same_question_as_a_select_and_is_not_the_same_kind() {
6471 // Both offer a fixed set and both read `options`, so the two
6472 // constructors differ in exactly one thing. That one thing is the
6473 // point: a renderer decides whether the alternatives are readable
6474 // without opening anything, and it can only decide that if the
6475 // description said which question was asked.
6476 let styles = [
6477 Choice::new("copy", "Copy samples in"),
6478 Choice::new("reference", "Reference in place"),
6479 ];
6480 let radio = Field::radio("storage", "Storage style", &styles);
6481 let select = Field::select("storage", "Storage style", &styles);
6482
6483 assert_eq!(radio.kind, FieldKind::Radio);
6484 assert_ne!(radio.kind, select.kind);
6485 assert_eq!(radio.options, select.options);
6486 assert_eq!(
6487 Field {
6488 kind: select.kind,
6489 ..radio
6490 },
6491 select
6492 );
6493 }
6494
6495 #[test]
6496 fn an_unavailable_option_cannot_be_silent_about_it() {
6497 // The whole content of the one-member shape: saying an option is not
6498 // pickable and saying why are the same act, so the greyed-out-with-no-
6499 // reason state is unsayable rather than merely discouraged.
6500 let multi =
6501 Choice::new("multi", "Multi-sample").unless("Drop a second sample onto the keyboard.");
6502 assert!(!multi.available());
6503 assert_eq!(
6504 multi.unavailable,
6505 Some("Drop a second sample onto the keyboard.")
6506 );
6507
6508 // And the option is still in the list, carrying what it submits, so a
6509 // renderer draws it rather than the app dropping it.
6510 assert_eq!(multi.value, "multi");
6511 assert_eq!(multi.label, "Multi-sample");
6512 }
6513
6514 #[test]
6515 fn a_range_carries_both_ends_and_a_validated_number_need_not() {
6516 // The distinction the kind exists for, asserted rather than only
6517 // written down: bounds are a rule for one and the control itself for
6518 // the other.
6519 let threshold = Field::range("review", "Review above", "0", "1");
6520 assert_eq!(threshold.kind, FieldKind::Range);
6521 assert!(threshold.bounded());
6522 assert_eq!(threshold.min, Some("0"));
6523 assert_eq!(threshold.max, Some("1"));
6524 // Granularity is the host's until an app says otherwise.
6525 assert_eq!(threshold.step, None);
6526
6527 // goingson's duration: a typed number with a floor, and it must not
6528 // read as a slider.
6529 let minutes = Field {
6530 min: Some("1"),
6531 ..Field::new(FieldKind::Number, "minutes", "Minutes")
6532 };
6533 assert_ne!(minutes.kind, FieldKind::Range);
6534 assert!(!minutes.bounded(), "one end is a rule, not an extent");
6535 }
6536
6537 #[test]
6538 fn a_range_described_with_one_end_says_so_rather_than_being_refused() {
6539 // Nothing here enforces the pair, for the reason nothing here enforces
6540 // `required`: the description states the constraint and the renderer
6541 // asks. What it must not do is look bounded.
6542 let half = Field {
6543 max: Some("1"),
6544 ..Field::new(FieldKind::Range, "review", "Review above")
6545 };
6546 assert!(!half.bounded());
6547 }
6548
6549 #[test]
6550 fn exactly_the_option_taking_kinds_say_so() {
6551 // The renderers branch on this rather than on a list of their own, so
6552 // a kind added without a decision here renders its options nowhere.
6553 assert!(FieldKind::Select.offers_options());
6554 assert!(FieldKind::Radio.offers_options());
6555 for kind in [
6556 FieldKind::Text,
6557 FieldKind::Secret,
6558 FieldKind::Number,
6559 FieldKind::Email,
6560 FieldKind::Url,
6561 FieldKind::Tel,
6562 FieldKind::Range,
6563 FieldKind::Textarea,
6564 FieldKind::Rich,
6565 FieldKind::Checkbox,
6566 FieldKind::Hidden,
6567 ] {
6568 assert!(!kind.offers_options(), "{kind:?} does not offer options");
6569 }
6570 }
6571
6572 #[test]
6573 fn a_radio_group_takes_a_label_even_though_its_options_carry_their_own() {
6574 // The near-miss: each option is labelled beside its own button, so a
6575 // renderer could plausibly read the group as self-labelling and drop
6576 // the question. Checkbox is the only kind that does that.
6577 assert!(!FieldKind::Radio.labels_itself());
6578 assert!(FieldKind::Checkbox.labels_itself());
6579 }
6580
6581 #[test]
6582 fn a_select_with_no_options_is_sayable() {
6583 // An app whose option list has not loaded has exactly this. Making it
6584 // unrepresentable would push the state somewhere less visible, and a
6585 // renderer drawing an empty select reports it on screen.
6586 let loading = Field::select("project", "Project", &[]);
6587 assert!(loading.options.is_empty());
6588 }
6589
6590 #[test]
6591 fn the_description_carries_the_question_and_never_the_answer() {
6592 // The line 0.8.0 drew. Placeholder and options are properties of what
6593 // is being asked; the current value is what came back, and no field
6594 // here holds one.
6595 let f = Field {
6596 placeholder: Some("yyyy-mm-dd"),
6597 ..Field::new(FieldKind::Text, "due", "Due")
6598 };
6599 assert_eq!(f.placeholder, Some("yyyy-mm-dd"));
6600 // A placeholder is not a label, and having one does not excuse the
6601 // field from carrying the other.
6602 assert_eq!(f.label, "Due");
6603 }
6604
6605 #[test]
6606 fn a_field_reports_its_own_error_state() {
6607 let mut f = Field::new(FieldKind::Text, "title", "Title");
6608 assert!(!f.invalid());
6609 f.error = Some("Required");
6610 assert!(f.invalid());
6611 }
6612
6613 #[test]
6614 fn columns_drop_by_priority_and_never_by_position() {
6615 let cols = [
6616 Column {
6617 width: Width::Fill,
6618 priority: Priority::Essential,
6619 ..Column::new("Title")
6620 },
6621 Column {
6622 width: Width::Fixed,
6623 priority: Priority::Secondary,
6624 ..Column::new("Due")
6625 },
6626 Column {
6627 width: Width::Fixed,
6628 priority: Priority::Optional,
6629 ..Column::new("Estimate")
6630 },
6631 ];
6632
6633 // Widest: everything survives.
6634 assert_eq!(
6635 cols.iter()
6636 .filter(|c| c.kept_at(Priority::Optional))
6637 .count(),
6638 3
6639 );
6640 // Narrower: the optional column goes first.
6641 let kept: Vec<_> = cols
6642 .iter()
6643 .filter(|c| c.kept_at(Priority::Secondary))
6644 .map(|c| c.name)
6645 .collect();
6646 assert_eq!(kept, ["Title", "Due"]);
6647 // Narrowest: only what identifies the row.
6648 let kept: Vec<_> = cols
6649 .iter()
6650 .filter(|c| c.kept_at(Priority::Essential))
6651 .map(|c| c.name)
6652 .collect();
6653 assert_eq!(kept, ["Title"]);
6654 }
6655
6656 #[test]
6657 fn inserting_a_column_does_not_move_what_gets_dropped() {
6658 // The bug the ordinal form has and this form cannot: goingson hides
6659 // `nth-child(n+5)` against a seven-column table, so a column inserted
6660 // anywhere to the left silently hides a different one.
6661 let before = [
6662 Column::new("Title"),
6663 Column {
6664 width: Width::Fixed,
6665 priority: Priority::Optional,
6666 ..Column::new("Estimate")
6667 },
6668 ];
6669 let after = [
6670 Column::new("Title"),
6671 Column::new("Project"), // inserted
6672 Column {
6673 width: Width::Fixed,
6674 priority: Priority::Optional,
6675 ..Column::new("Estimate")
6676 },
6677 ];
6678
6679 fn dropped<'a>(cols: &[Column<'a>]) -> Vec<&'a str> {
6680 cols.iter()
6681 .filter(|c| !c.kept_at(Priority::Secondary))
6682 .map(|c| c.name)
6683 .collect()
6684 }
6685 assert_eq!(dropped(&before), ["Estimate"]);
6686 assert_eq!(dropped(&after), ["Estimate"]);
6687 }
6688
6689 #[test]
6690 fn an_arrangement_carries_the_tab_group_as_a_modifier() {
6691 // goingson uses the tab group inside the content region rather than
6692 // instead of one, so it is not a third arrangement.
6693 let go = Arrangement::list_detail(true);
6694 let plain = Arrangement::list_detail(false);
6695 assert_ne!(go, plain);
6696 assert_ne!(go, Arrangement::sidebar_content());
6697 }
6698
6699 #[test]
6700 fn a_share_is_a_proportion_and_resolves_the_same_way_everywhere() {
6701 // The point of the member: a terminal reading columns and a webview
6702 // reading a grid honour one fact, so two hosts showing one screen agree
6703 // about its proportions.
6704 assert_eq!(Share::LIST.as_percent(), 40);
6705 assert_eq!(Share::LIST.of(100), 40);
6706 assert_eq!(
6707 Share::SIDEBAR.of(96),
6708 24,
6709 "quasi-tui's 24 columns, said as a quarter"
6710 );
6711 }
6712
6713 #[test]
6714 fn a_region_never_resolves_to_nothing() {
6715 // A region the description named should be visible. A zero-width one
6716 // reads on screen as a region that vanished, which is the hardest kind
6717 // of bug to find from what is drawn.
6718 assert_eq!(Share::percent(5).of(1), 1);
6719 assert_eq!(Share::percent(5).of(0), 1);
6720 }
6721
6722 #[test]
6723 fn a_share_outside_the_range_is_clamped_rather_than_refused() {
6724 assert_eq!(Share::percent(0), Share::percent(5));
6725 assert_eq!(Share::percent(200), Share::percent(95));
6726 }
6727
6728 #[test]
6729 fn the_share_rides_on_the_arrangement_that_knows_which_question_it_is() {
6730 // How much a sidebar takes and how much a list side takes are different
6731 // questions, and this enum is the only thing that knows which is being
6732 // asked.
6733 assert_eq!(Arrangement::sidebar_content().share(), Share::SIDEBAR);
6734 assert_eq!(Arrangement::list_detail(false).share(), Share::LIST);
6735
6736 let narrow = Arrangement::sidebar_content().with_share(Share::percent(20));
6737 assert_eq!(narrow.share(), Share::percent(20));
6738 assert!(matches!(narrow, Arrangement::SidebarContent { .. }));
6739 }
6740
6741 #[test]
6742 fn a_measure_defaults_to_the_one_53_of_69_templates_asked_for() {
6743 // The default is meaningful: a screen nobody said anything about uses
6744 // the window it was given.
6745 assert_eq!(Measure::default(), Measure::Wide);
6746 assert_eq!(Measure::Reading.as_str(), "reading");
6747 }
6748
6749 #[test]
6750 fn readiness_names_the_state_and_not_the_shimmer() {
6751 // Two members and no third. If a skeleton ever appears in this enum,
6752 // the deferral rule has been broken.
6753 assert_ne!(Readiness::Ready, Readiness::Pending);
6754 }
6755
6756 #[test]
6757 fn a_window_with_no_length_still_answers_what_it_can() {
6758 // The uncounted case is the common one, not the degenerate one: a query
6759 // that asked for 51 to learn there were more than 50 knows there are,
6760 // and not how many.
6761 let uncounted = Window::new(100, 50);
6762 assert_eq!(uncounted.index(), Some(2));
6763 assert_eq!(uncounted.windows(), None);
6764 assert!(uncounted.has_before());
6765 // Unknown length cannot rule out more, and offering a way forward that
6766 // turns out empty is the cheaper mistake.
6767 assert!(uncounted.has_after());
6768 }
6769
6770 #[test]
6771 fn a_counted_window_knows_where_it_ends() {
6772 let last = Window::new(350, 50).of(400);
6773 assert_eq!(last.index(), Some(7));
6774 assert_eq!(last.windows(), Some(8));
6775 assert!(last.has_before());
6776 assert!(!last.has_after());
6777
6778 let first = Window::new(0, 50).of(400);
6779 assert!(!first.has_before());
6780 assert!(first.has_after());
6781 }
6782
6783 #[test]
6784 fn a_window_that_does_not_divide_evenly_rounds_up() {
6785 // 401 rows in pages of 50 is eight pages and a straggler, which is nine
6786 // pages. Rounding down would make the last one unreachable.
6787 assert_eq!(Window::new(0, 50).of(401).windows(), Some(9));
6788 }
6789
6790 #[test]
6791 fn a_zero_count_answers_none_rather_than_dividing() {
6792 let empty = Window::new(0, 0).of(400);
6793 assert_eq!(empty.index(), None);
6794 assert_eq!(empty.windows(), None);
6795 // And it still clamps rather than panicking.
6796 assert_eq!(Window::new(900, 0).of(400).clamped().from, 399);
6797 }
6798
6799 #[test]
6800 fn a_window_past_the_end_clamps_inside_rather_than_vanishing() {
6801 // `Slot::current`'s reasoning, one layer down: a description pointing
6802 // past the end is a host bug, and answering it by drawing nothing
6803 // reports a region that vanished.
6804 assert_eq!(Window::new(900, 50).of(400).clamped().from, 350);
6805 // Nothing to clamp against when the length is unknown.
6806 assert_eq!(Window::new(900, 50).clamped().from, 900);
6807 }
6808
6809 #[test]
6810 fn a_carousel_frame_is_a_window_of_one() {
6811 // The shape a carousel instantiates. Same code as a paged list, which is
6812 // the whole reason `Window` exists rather than two copies of it.
6813 let third = Window::frame(2, 5);
6814 assert_eq!(third.index(), Some(2));
6815 assert_eq!(third.windows(), Some(5));
6816 assert!(third.has_before());
6817 assert!(third.has_after());
6818
6819 let last = Window::frame(4, 5);
6820 assert!(!last.has_after());
6821 }
6822
6823 #[test]
6824 fn numbered_pages_read_from_one_and_load_more_has_no_page() {
6825 // The page number is read aloud, so it is one-based; `Window::index` is
6826 // the zero-based form for indexing.
6827 let third = Paging::pages(100, 50).of(400);
6828 assert_eq!(third.page(), Some(3));
6829 assert_eq!(third.pages_total(), Some(8));
6830 assert_eq!(third.total(), Some(400));
6831 assert!(third.has_previous());
6832 assert!(third.has_more());
6833
6834 // Load-more grew a window from the start, so "page 2" would name
6835 // nothing and the type says so rather than inventing one.
6836 let grown = Paging::more(150).of(400);
6837 assert_eq!(grown.page(), None);
6838 assert_eq!(grown.pages_total(), None);
6839 assert_eq!(grown.shown(), 150);
6840 assert!(!grown.has_previous());
6841 assert!(grown.has_more());
6842 }
6843
6844 #[test]
6845 fn an_uncounted_paging_offers_forward_and_admits_no_total() {
6846 // What a host that will not pay for a COUNT describes. `None` here is
6847 // permanent: a total arriving later would widen the text that prints it,
6848 // which is the reflow "first paint is final paint" forbids.
6849 let feed = Paging::more(50);
6850 assert_eq!(feed.total(), None);
6851 assert_eq!(feed.pages_total(), None);
6852 assert_eq!(feed.remaining(), None);
6853 assert!(feed.has_more());
6854 }
6855
6856 #[test]
6857 fn what_is_left_is_derived_and_never_underflows() {
6858 assert_eq!(Paging::more(150).of(400).remaining(), Some(250));
6859 assert_eq!(Paging::pages(350, 50).of(400).remaining(), Some(0));
6860 // A host that overshot its own total gets zero rather than a wrapped
6861 // usize, which would print as "18446744073709551516 remaining".
6862 assert_eq!(Paging::more(500).of(400).remaining(), Some(0));
6863 }
6864
6865 #[test]
6866 fn a_group_out_of_room_is_not_the_same_fact_as_a_narrow_window() {
6867 // The case the type exists for: 913px is a roomy window holding a group
6868 // that has run out of room, so room is measured against the group's own
6869 // allocation and never against the viewport.
6870 assert!(Room::Tight < Room::Ample);
6871 // A group nesting another has whichever room is scarcer, which is what
6872 // makes relief resolve inside-out rather than by declaration order.
6873 assert_eq!(Room::Ample.min(Room::Tight), Room::Tight);
6874 }
6875
6876 #[test]
6877 fn a_fallback_is_authored_and_a_group_cannot_omit_it() {
6878 // No `Default`. The compiler is what enforces rule 2, so the assertion
6879 // that matters is one this file cannot write; what it can say is that
6880 // the four authored answers are distinct and none is privileged.
6881 let all = [
6882 Fallback::Wrap,
6883 Fallback::Stack,
6884 Fallback::Shed,
6885 Fallback::Menu,
6886 ];
6887 for (i, a) in all.iter().enumerate() {
6888 for b in &all[i + 1..] {
6889 assert_ne!(a, b);
6890 }
6891 }
6892 }
6893
6894 #[test]
6895 fn shedding_stops_at_essential_whatever_the_group_holds() {
6896 // Priority is read the same way for a group member as for a column,
6897 // which is the whole claim of generalising it off `Column`.
6898 let members = [
6899 ("tabs", Priority::Essential),
6900 ("search", Priority::Secondary),
6901 ("count", Priority::Optional),
6902 ];
6903 let kept: Vec<_> = members
6904 .iter()
6905 .filter(|(_, p)| *p >= Priority::Essential)
6906 .map(|(n, _)| *n)
6907 .collect();
6908 assert_eq!(kept, ["tabs"]);
6909 }
6910
6911 #[test]
6912 fn a_role_says_what_a_part_is_worth_when_the_run_does_not_fit() {
6913 // The row still identifies itself after everything droppable has gone,
6914 // which is the property the ladder exists for.
6915 assert_eq!(RowPart::Primary.priority(), Priority::Essential);
6916 // A control is not a fact. Room comes out of what the row says, never
6917 // out of what it offers.
6918 assert_eq!(RowPart::Actions.priority(), Priority::Essential);
6919 assert_eq!(RowPart::Meta.priority(), Priority::Optional);
6920 assert_eq!(RowPart::Proportion.priority(), Priority::Optional);
6921 assert_eq!(RowPart::Secondary.priority(), Priority::Secondary);
6922 // Tokens sit in the middle deliberately: a toned badge is often the
6923 // most scannable thing in a row, so it does not go first.
6924 assert_eq!(RowPart::Tokens.priority(), Priority::Secondary);
6925 }
6926
6927 #[test]
6928 fn a_run_is_one_line_unless_the_description_says_two() {
6929 // The default is what every part did before flows existed, so a
6930 // description written against the old vocabulary keeps its rendering.
6931 assert_eq!(Flow::default(), Flow::Tight);
6932 assert_eq!(Flow::Tight.lines(), 1);
6933 assert_eq!(Flow::Relaxed.lines(), 2);
6934 }
6935
6936 #[test]
6937 fn an_unknown_flow_reads_as_one_line() {
6938 // `#[non_exhaustive]`'s cost, taken deliberately. A tier added upstream
6939 // reaches an old renderer as one line rather than as a build break, and
6940 // one line is the reading that cannot break a neighbour's layout. The
6941 // match in `lines` is what this holds; it fails if a new tier is given
6942 // an arm that returns something unbounded.
6943 for flow in [Flow::Tight, Flow::Relaxed] {
6944 assert!((1..=2).contains(&flow.lines()));
6945 }
6946 }
6947
6948 #[test]
6949 fn an_awaiting_mark_is_indeterminate_until_something_is_measured() {
6950 // The default is the common case: a call waits, and nothing about it is
6951 // countable. A determinate bar is the exception and says so.
6952 assert_eq!(Awaiting::default(), Awaiting::unmeasured());
6953 assert!(!Awaiting::unmeasured().is_determinate());
6954 assert!(Awaiting::of(40 * 1024 * 1024).is_determinate());
6955 assert_eq!(Awaiting::of(7).amount, Some(7));
6956 }
6957
6958 // A slider is a fraction and a mapping
6959 //
6960 // `Curve` is the one thing in this crate that computes rather than
6961 // describes, and it does so because four renderers would otherwise each
6962 // write these two formulas and drift. So the formulas are pinned here.
6963
6964 /// The bounds of audiofiles' envelope attack, the curve's first consumer.
6965 const ATTACK: (f64, f64) = (0.001, 5.0);
6966
6967 #[test]
6968 fn a_curve_is_linear_with_no_step_until_a_field_says_otherwise() {
6969 assert_eq!(Curve::default(), Curve::Linear { step: None });
6970 let plain = Field::range("t", "T", "0", "1");
6971 assert_eq!(plain.curve, Curve::Linear { step: None });
6972 assert_eq!(plain.curve.step(), None);
6973 }
6974
6975 #[test]
6976 fn every_curve_carries_its_own_granularity() {
6977 assert_eq!(Curve::Linear { step: Some("0.01") }.step(), Some("0.01"));
6978 assert_eq!(
6979 Curve::Logarithmic {
6980 step: Some("0.001")
6981 }
6982 .step(),
6983 Some("0.001")
6984 );
6985 }
6986
6987 #[test]
6988 fn both_ends_of_the_track_are_the_bounds_under_either_curve() {
6989 // `min` and `max` are `f(0)` and `f(1)`. That is the whole reframe, and
6990 // it has to hold for a mapping that is not the identity or the bounds
6991 // have stopped meaning what the field says they mean.
6992 let (min, max) = ATTACK;
6993 for curve in [
6994 Curve::Linear { step: None },
6995 Curve::Logarithmic { step: None },
6996 ] {
6997 assert!((curve.value_at(0.0, min, max) - min).abs() < 1e-12);
6998 assert!((curve.value_at(1.0, min, max) - max).abs() < 1e-12);
6999 }
7000 }
7001
7002 #[test]
7003 fn a_linear_midpoint_is_the_average_and_a_ratio_midpoint_is_the_geometric_mean() {
7004 let (min, max) = ATTACK;
7005 let linear = Curve::Linear { step: None }.value_at(0.5, min, max);
7006 assert!((linear - 2.5005).abs() < 1e-9);
7007
7008 // The reason the envelope is not linear: half way along a log track is
7009 // 70 ms, and half way along a linear one is 2.5 seconds. Every attack a
7010 // sampler is actually played with lives below the first.
7011 let ratio = Curve::Logarithmic { step: None }.value_at(0.5, min, max);
7012 assert!((ratio - (min * max).sqrt()).abs() < 1e-12);
7013 assert!(ratio < 0.08);
7014 }
7015
7016 #[test]
7017 fn a_position_and_a_value_round_trip_under_either_curve() {
7018 let (min, max) = ATTACK;
7019 for curve in [
7020 Curve::Linear { step: None },
7021 Curve::Logarithmic { step: None },
7022 ] {
7023 for position in [0.0, 0.1, 0.25, 0.5, 0.75, 0.99, 1.0] {
7024 let back = curve.position_of(curve.value_at(position, min, max), min, max);
7025 assert!(
7026 (back - position).abs() < 1e-9,
7027 "{curve:?} lost {position} (got {back})"
7028 );
7029 }
7030 }
7031 }
7032
7033 #[test]
7034 fn a_ratio_curve_across_zero_is_drawn_linearly_rather_than_refused() {
7035 // An envelope's sustain is a 0-to-1 level. A constant ratio is
7036 // undefined there, and the answer is the linear mapping rather than a
7037 // NaN reaching a renderer that would paint it.
7038 let curve = Curve::Logarithmic { step: None };
7039 assert!(!curve.is_ratio(0.0, 1.0));
7040 assert!((curve.value_at(0.5, 0.0, 1.0) - 0.5).abs() < 1e-12);
7041 assert!(curve.value_at(0.5, -96.0, -20.0).is_finite());
7042 assert!(curve.is_ratio(ATTACK.0, ATTACK.1));
7043 }
7044
7045 #[test]
7046 fn a_track_with_no_extent_has_one_value_on_it() {
7047 for curve in [
7048 Curve::Linear { step: None },
7049 Curve::Logarithmic { step: None },
7050 ] {
7051 assert!((curve.value_at(0.7, 4.0, 4.0) - 4.0).abs() < f64::EPSILON);
7052 assert!(curve.position_of(4.0, 4.0, 4.0).abs() < f64::EPSILON);
7053 // Inverted bounds are the same degenerate answer, not a negative
7054 // extent a renderer would draw backwards.
7055 assert!((curve.value_at(0.7, 9.0, 2.0) - 9.0).abs() < f64::EPSILON);
7056 }
7057 }
7058
7059 #[test]
7060 fn a_position_or_a_value_outside_the_track_is_clamped_to_it() {
7061 let (min, max) = ATTACK;
7062 let curve = Curve::Logarithmic { step: None };
7063 assert!((curve.value_at(-3.0, min, max) - min).abs() < 1e-12);
7064 assert!((curve.value_at(4.0, min, max) - max).abs() < 1e-12);
7065 assert!(curve.position_of(0.0, min, max).abs() < 1e-12);
7066 assert!((curve.position_of(500.0, min, max) - 1.0).abs() < 1e-12);
7067 }
7068
7069 #[test]
7070 fn a_typed_number_keeps_its_own_step_and_a_range_reads_its_curve() {
7071 // The split the 0.32.0 narrowing is: two granularities that were one
7072 // member, and the kinds that take them do not overlap.
7073 let typed = Field {
7074 step: Some("5"),
7075 ..Field::new(FieldKind::Number, "port", "Port")
7076 };
7077 assert_eq!(typed.step, Some("5"));
7078
7079 let slid = Field {
7080 curve: Curve::Logarithmic {
7081 step: Some("0.001"),
7082 },
7083 ..Field::range("attack", "Attack", "0.001", "5")
7084 };
7085 assert_eq!(slid.step, None);
7086 assert_eq!(slid.curve.step(), Some("0.001"));
7087 }
7088 }
7089