max / makenotwork

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1	//! The one macro every enum here is built with.
2	//!
3	//! `macro_rules!` is textually scoped, so a sibling cannot see it by being a
4	//! sibling: it reaches them through the `pub(super) use` at the bottom of this
5	//! file, and each sibling imports it by name.
6
7	/// Generate `Display`, `FromStr`, and sqlx `Type`/`Encode`/`Decode` impls
8	/// for a simple enum ↔ string mapping. The sqlx impls delegate to `String`
9	/// so the enum is compatible with any text-like column (TEXT, VARCHAR, etc.).
10	macro_rules! impl_str_enum {
11	($enum_name:ident { $($variant:ident => $str:literal),+ $(,)? }) => {
12	impl std::fmt::Display for $enum_name {
13	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
14	let s = match self {
15	$( Self::$variant => $str, )+
16	};
17	f.write_str(s)
18	}
19	}
20
21	impl std::str::FromStr for $enum_name {
22	type Err = String;
23
24	fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
25	match s {
26	$( $str => Ok(Self::$variant), )+
27	other => Err(format!("invalid {}: {other}", stringify!($enum_name))),
28	}
29	}
30	}
31
32	// sqlx Type: delegate to String so it's compatible with TEXT/VARCHAR.
33	impl sqlx::Type<sqlx::Postgres> for $enum_name {
34	fn type_info() -> sqlx::postgres::PgTypeInfo {
35	<String as sqlx::Type<sqlx::Postgres>>::type_info()
36	}
37
38	fn compatible(ty: &sqlx::postgres::PgTypeInfo) -> bool {
39	<String as sqlx::Type<sqlx::Postgres>>::compatible(ty)
40	}
41	}
42
43	// sqlx Encode: write the Display string.
44	impl sqlx::Encode<'_, sqlx::Postgres> for $enum_name {
45	fn encode_by_ref(
46	&self,
47	buf: &mut sqlx::postgres::PgArgumentBuffer,
48	) -> Result<sqlx::encode::IsNull, Box<dyn std::error::Error + Send + Sync>> {
49	<String as sqlx::Encode<'_, sqlx::Postgres>>::encode(self.to_string(), buf)
50	}
51	}
52
53	// sqlx Decode: parse the string value via FromStr.
54	impl sqlx::Decode<'_, sqlx::Postgres> for $enum_name {
55	fn decode(
56	value: sqlx::postgres::PgValueRef<'_>,
57	) -> std::result::Result<Self, Box<dyn std::error::Error + Send + Sync>> {
58	let s = <String as sqlx::Decode<'_, sqlx::Postgres>>::decode(value)?;
59	Ok(s.parse::<Self>()?)
60	}
61	}
62
63	// Allow comparison with string slices (useful in Askama templates).
64	impl PartialEq<&str> for $enum_name {
65	fn eq(&self, other: &&str) -> bool {
66	let s: &str = match self {
67	$( Self::$variant => $str, )+
68	};
69	s == *other
70	}
71	}
72
73	impl PartialEq<str> for $enum_name {
74	fn eq(&self, other: &str) -> bool {
75	let s: &str = match self {
76	$( Self::$variant => $str, )+
77	};
78	s == other
79	}
80	}
81
82	impl $enum_name {
83	/// Every wire/DB string this enum maps to, the single source of
84	/// truth for the variant set. For each enum registered in the
85	/// enum-drift integration test (`tests/workflows/enum_drift.rs`),
86	/// this set is asserted equal to the Postgres `CHECK (... IN (...))`
87	/// list on its backing column, so a variant added here without
88	/// widening the DB constraint (or vice versa) fails at test time
89	/// rather than at the first read of a poisoned row. Coverage is that
90	/// registry, not every enum automatically: add a `(enum, table,
91	/// column)` row there when a new CHECK-constrained column lands.
92	pub const VARIANTS: &'static [&'static str] = &[$($str),+];
93	}
94	};
95	}
96
97	pub(super) use impl_str_enum;
98