codama_attributes/
repr_attribute.rs

1use crate::Attribute;
2use codama_errors::CodamaError;
3use codama_nodes::{NumberFormat, NumberTypeNode};
4use codama_syn_helpers::extensions::*;
5
6#[derive(Debug, PartialEq)]
7pub struct ReprAttribute<'a> {
8    pub ast: &'a syn::Attribute,
9    pub metas: Vec<syn::Meta>,
10}
11
12impl<'a> ReprAttribute<'a> {
13    pub fn parse(ast: &'a syn::Attribute) -> syn::Result<Self> {
14        let unfeatured = ast.unfeatured();
15        let effective = unfeatured.as_ref().unwrap_or(ast);
16        Self::parse_from(ast, effective)
17    }
18
19    /// Parse a repr attribute using the effective attribute for content extraction.
20    /// `ast` is stored as the original attribute reference (for error spans).
21    /// `effective` is used to parse the actual repr list.
22    pub fn parse_from(ast: &'a syn::Attribute, effective: &syn::Attribute) -> syn::Result<Self> {
23        let list = effective.meta.require_list()?;
24        if !list.path.is_strict("repr") {
25            return Err(list.path.error("expected #[repr(...)]"));
26        };
27
28        let metas = list.parse_comma_args::<syn::Meta>()?;
29        Ok(Self { ast, metas })
30    }
31
32    pub fn get_number_type_node(&self) -> Option<NumberTypeNode> {
33        self.metas.iter().find_map(|meta| match meta {
34            syn::Meta::Path(p) => match NumberFormat::try_from(p.to_string()) {
35                Ok(n) => Some(NumberTypeNode::le(n)),
36                Err(_) => None,
37            },
38            _ => None,
39        })
40    }
41}
42
43impl<'a> TryFrom<&'a Attribute<'a>> for &'a ReprAttribute<'a> {
44    type Error = CodamaError;
45
46    fn try_from(attribute: &'a Attribute) -> Result<Self, Self::Error> {
47        match attribute {
48            Attribute::Repr(a) => Ok(a),
49            _ => Err(CodamaError::InvalidAttribute {
50                expected: "repr".to_string(),
51                actual: attribute.name(),
52            }),
53        }
54    }
55}
56
57#[cfg(test)]
58mod tests {
59    use super::*;
60    use codama_nodes::NumberFormat::U32;
61    use syn::parse_quote;
62
63    #[test]
64    fn test_repr_attribute() {
65        let ast = parse_quote! { #[repr(u32, align(4))] };
66        let attribute = ReprAttribute::parse(&ast).unwrap();
67
68        assert_eq!(attribute.ast, &ast);
69        assert_eq!(
70            attribute.metas,
71            [(parse_quote! { u32 }), (parse_quote! { align(4) })]
72        );
73    }
74
75    #[test]
76    fn test_feature_gated_repr_attribute() {
77        let ast = parse_quote! { #[cfg_attr(feature = "some_feature", repr(u32, align(4)))] };
78        let attribute = ReprAttribute::parse(&ast).unwrap();
79
80        assert_eq!(attribute.ast, &ast);
81        assert_eq!(
82            attribute.metas,
83            [(parse_quote! { u32 }), (parse_quote! { align(4) })]
84        );
85    }
86
87    #[test]
88    fn test_get_number_type_node() {
89        let ast = parse_quote! { #[repr(u32, align(4), u64)] };
90        let attribute = ReprAttribute::parse(&ast).unwrap();
91
92        assert_eq!(
93            attribute.get_number_type_node(),
94            Some(NumberTypeNode::le(U32))
95        );
96    }
97}
codama_attributes/repr_attribute.rs

codama_attributes/
repr_attribute.rs
