max / makenotwork

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1	//! The leaf value type flowing through substitution and filters.
2
3	use std::fmt;
4
5	/// A leaf value: the result of resolving a `{{ path }}` before and after
6	/// filters run. Callers populate a [`crate::Substituter`] with these and read
7	/// them back out with `get`.
8	#[derive(Debug, Clone, PartialEq)]
9	pub enum Value {
10	Int(i64),
11	Float(f64),
12	String(String),
13	}
14
15	impl Value {
16	/// Coerce to `f64` for numeric filters. `Int` is widened; `String` returns `None`.
17	pub fn as_f64(&self) -> Option<f64> {
18	match self {
19	Self::Int(n) => Some(*n as f64),
20	Self::Float(x) => Some(*x),
21	Self::String(_) => None,
22	}
23	}
24	}
25
26	impl fmt::Display for Value {
27	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
28	match self {
29	Self::Int(n) => write!(f, "{n}"),
30	Self::Float(x) => f.write_str(&format_float(*x)),
31	Self::String(s) => f.write_str(s),
32	}
33	}
34	}
35
36	/// Format a float with up to 4 decimal places, trimming trailing zeros.
37	///
38	/// `22.0 -> "22"`, `0.59 -> "0.59"`, `0.0367 -> "0.0367"`, `61960.0 -> "61960"`.
39	fn format_float(x: f64) -> String {
40	let s = format!("{x:.4}");
41	let trimmed = s.trim_end_matches('0').trim_end_matches('.');
42	trimmed.to_string()
43	}
44
45	#[cfg(test)]
46	mod tests {
47	use super::*;
48
49	#[test]
50	fn float_formatting_strips_trailing_zeros() {
51	assert_eq!(format_float(22.0), "22");
52	assert_eq!(format_float(0.59), "0.59");
53	assert_eq!(format_float(61960.0), "61960");
54	assert_eq!(format_float(0.5), "0.5");
55	assert_eq!(format_float(1.085), "1.085");
56	}
57
58	#[test]
59	fn as_f64_widens_int_and_rejects_string() {
60	assert_eq!(Value::Int(5).as_f64(), Some(5.0));
61	assert_eq!(Value::Float(1.5).as_f64(), Some(1.5));
62	assert_eq!(Value::String("x".into()).as_f64(), None);
63	}
64
65	#[test]
66	fn display_matches_format() {
67	assert_eq!(Value::Int(580).to_string(), "580");
68	assert_eq!(Value::Float(0.5).to_string(), "0.5");
69	assert_eq!(Value::String("lifetime".into()).to_string(), "lifetime");
70	}
71	}
72