darling_core/util/
path_list.rs

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1use std::ops::Deref;
2
3use syn::{Meta, Path};
4
5use crate::ast::NestedMeta;
6use crate::{Error, FromMeta, Result};
7
8use super::path_to_string;
9
10/// A list of `syn::Path` instances. This type is used to extract a list of paths from an
11/// attribute.
12///
13/// # Usage
14/// An `PathList` field on a struct implementing `FromMeta` will turn `#[builder(derive(serde::Debug, Clone))]` into:
15///
16/// ```rust,ignore
17/// StructOptions {
18///     derive: PathList(vec![syn::Path::new("serde::Debug"), syn::Path::new("Clone")])
19/// }
20/// ```
21#[derive(Debug, Default, Clone, PartialEq, Eq)]
22pub struct PathList(Vec<Path>);
23
24impl PathList {
25    /// Create a new list.
26    pub fn new<T: Into<Path>>(vals: Vec<T>) -> Self {
27        PathList(vals.into_iter().map(T::into).collect())
28    }
29
30    /// Create a new `Vec` containing the string representation of each path.
31    pub fn to_strings(&self) -> Vec<String> {
32        self.0.iter().map(path_to_string).collect()
33    }
34}
35
36impl Deref for PathList {
37    type Target = Vec<Path>;
38
39    fn deref(&self) -> &Self::Target {
40        &self.0
41    }
42}
43
44impl From<Vec<Path>> for PathList {
45    fn from(v: Vec<Path>) -> Self {
46        PathList(v)
47    }
48}
49
50impl FromMeta for PathList {
51    fn from_list(v: &[NestedMeta]) -> Result<Self> {
52        let mut paths = Vec::with_capacity(v.len());
53        for nmi in v {
54            if let NestedMeta::Meta(Meta::Path(ref path)) = *nmi {
55                paths.push(path.clone());
56            } else {
57                return Err(Error::unexpected_type("non-word").with_span(nmi));
58            }
59        }
60
61        Ok(PathList(paths))
62    }
63}
64
65#[cfg(test)]
66mod tests {
67    use super::PathList;
68    use crate::FromMeta;
69    use proc_macro2::TokenStream;
70    use quote::quote;
71    use syn::{parse_quote, Attribute, Meta};
72
73    /// parse a string as a syn::Meta instance.
74    fn pm(tokens: TokenStream) -> ::std::result::Result<Meta, String> {
75        let attribute: Attribute = parse_quote!(#[#tokens]);
76        Ok(attribute.meta)
77    }
78
79    fn fm<T: FromMeta>(tokens: TokenStream) -> T {
80        FromMeta::from_meta(&pm(tokens).expect("Tests should pass well-formed input"))
81            .expect("Tests should pass valid input")
82    }
83
84    #[test]
85    fn succeeds() {
86        let paths = fm::<PathList>(quote!(ignore(Debug, Clone, Eq)));
87        assert_eq!(
88            paths.to_strings(),
89            vec![
90                String::from("Debug"),
91                String::from("Clone"),
92                String::from("Eq")
93            ]
94        );
95    }
96
97    /// Check that the parser rejects non-word members of the list, and that the error
98    /// has an associated span.
99    #[test]
100    fn fails_non_word() {
101        let input = PathList::from_meta(&pm(quote!(ignore(Debug, Clone = false))).unwrap());
102        let err = input.unwrap_err();
103        assert!(err.has_span());
104    }
105}
darling_core/util/path_list.rs

darling_core/util/
path_list.rs
