smelt_stdlib/
fields.rs

1//! Exact source field-name recognition metadata shared by frontends and codegen.
2
3/// Field read whose semantics come from the standard library rather than a
4/// user-defined type shape.
5#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
6#[non_exhaustive]
7pub enum FieldRule {
8    /// JavaScript `.length` on string/array-shaped receivers.
9    TsLength,
10    /// JavaScript `.constructor`, which Smelt erases to a null value.
11    TsConstructor,
12    /// JavaScript `.sort` read as a bound array method on erased receivers.
13    TsSort,
14}
15
16/// Return the shared field rule for an exact TypeScript field spelling.
17///
18/// Callers stay responsible for receiver-shape checks; this only resolves the
19/// stdlib identity of the field name itself.
20#[must_use]
21pub fn typescript_field_rule(field: &str) -> Option<FieldRule> {
22    match field {
23        "length" => Some(FieldRule::TsLength),
24        "constructor" => Some(FieldRule::TsConstructor),
25        "sort" => Some(FieldRule::TsSort),
26        _ => None,
27    }
28}
29
30#[cfg(test)]
31mod tests {
32    use super::*;
33
34    /// Exact stdlib field spellings resolve to their registry identity.
35    #[test]
36    fn recognizes_stdlib_field_names() {
37        assert_eq!(typescript_field_rule("length"), Some(FieldRule::TsLength));
38        assert_eq!(
39            typescript_field_rule("constructor"),
40            Some(FieldRule::TsConstructor)
41        );
42        assert_eq!(typescript_field_rule("sort"), Some(FieldRule::TsSort));
43    }
44
45    /// Ordinary user field names never resolve to a stdlib rule.
46    #[test]
47    fn rejects_user_field_names() {
48        for field in ["len", "lengthInMeters", "construct", "sorted", "value"] {
49            assert_eq!(typescript_field_rule(field), None);
50        }
51    }
52}
smelt_stdlib/fields.rs

smelt_stdlib/
fields.rs
