darling_core/util/
ident_string.rs

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1use std::fmt;
2use std::hash::{Hash, Hasher};
3
4use proc_macro2::{Span, TokenStream};
5use quote::ToTokens;
6use syn::{Ident, Meta};
7
8use crate::{FromMeta, Result};
9
10/// A wrapper for an `Ident` which also keeps the value as a string.
11///
12/// This struct can be used to perform string comparisons and operations.
13#[derive(Clone, PartialOrd, Ord)]
14pub struct IdentString {
15    ident: Ident,
16    string: String,
17}
18
19impl IdentString {
20    /// Create a new `IdentString`.
21    pub fn new(ident: Ident) -> Self {
22        IdentString {
23            string: ident.to_string(),
24            ident,
25        }
26    }
27
28    /// Get the ident as a `proc_macro2::Ident`.
29    pub fn as_ident(&self) -> &Ident {
30        &self.ident
31    }
32
33    /// Get the ident as a string.
34    pub fn as_str(&self) -> &str {
35        &self.string
36    }
37
38    /// Get the location of this `Ident` in source.
39    pub fn span(&self) -> Span {
40        self.ident.span()
41    }
42
43    /// Apply some transform to the ident's string representation.
44    ///
45    /// # Panics
46    /// This will panic if the transform produces an invalid ident.
47    pub fn map<F, S>(self, map_fn: F) -> Self
48    where
49        F: FnOnce(String) -> S,
50        S: AsRef<str>,
51    {
52        let span = self.span();
53        let string = map_fn(self.string);
54        Ident::new(string.as_ref(), span).into()
55    }
56}
57
58impl AsRef<Ident> for IdentString {
59    fn as_ref(&self) -> &Ident {
60        self.as_ident()
61    }
62}
63
64impl AsRef<str> for IdentString {
65    fn as_ref(&self) -> &str {
66        self.as_str()
67    }
68}
69
70impl From<Ident> for IdentString {
71    fn from(ident: Ident) -> Self {
72        IdentString::new(ident)
73    }
74}
75
76impl From<IdentString> for Ident {
77    fn from(v: IdentString) -> Ident {
78        v.ident
79    }
80}
81
82impl From<IdentString> for String {
83    fn from(v: IdentString) -> String {
84        v.string
85    }
86}
87
88impl Eq for IdentString {}
89
90impl PartialEq for IdentString {
91    fn eq(&self, rhs: &Self) -> bool {
92        self.ident == rhs.ident
93    }
94}
95
96impl PartialEq<String> for IdentString {
97    fn eq(&self, rhs: &String) -> bool {
98        self.as_str() == rhs
99    }
100}
101
102impl<'a> PartialEq<&'a str> for IdentString {
103    fn eq(&self, rhs: &&str) -> bool {
104        self.as_str() == *rhs
105    }
106}
107
108impl Hash for IdentString {
109    fn hash<H: Hasher>(&self, state: &mut H) {
110        self.ident.hash(state);
111    }
112}
113
114impl ToTokens for IdentString {
115    fn to_tokens(&self, tokens: &mut TokenStream) {
116        self.ident.to_tokens(tokens);
117    }
118}
119
120impl fmt::Debug for IdentString {
121    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
122        write!(f, "{:?}", self.ident)
123    }
124}
125
126impl fmt::Display for IdentString {
127    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
128        write!(f, "{}", self.ident)
129    }
130}
131
132impl FromMeta for IdentString {
133    fn from_meta(item: &Meta) -> Result<Self> {
134        Ident::from_meta(item).map(IdentString::from)
135    }
136}
137
138#[cfg(test)]
139mod tests {
140    use syn::parse_quote;
141
142    use super::IdentString;
143
144    #[test]
145    fn convert() {
146        let i_str = IdentString::new(parse_quote!(t));
147        assert_eq!(i_str.as_str(), "t");
148    }
149
150    #[test]
151    fn map_transform() {
152        let i = IdentString::new(parse_quote!(my));
153        let after = i.map(|v| format!("var_{}", v));
154        assert_eq!(after, "var_my");
155        assert_eq!(after, String::from("var_my"));
156    }
157}
darling_core/util/ident_string.rs

darling_core/util/
ident_string.rs
