syn/
ident.rs

1// SPDX-License-Identifier: Apache-2.0 OR MIT
2
3#[cfg(feature = "parsing")]
4use crate::lookahead;
5
6pub use proc_macro2::Ident;
7
8#[cfg(feature = "parsing")]
9pub_if_not_doc! {
10    #[doc(hidden)]
11    #[allow(non_snake_case)]
12    pub fn Ident(marker: lookahead::TokenMarker) -> Ident {
13        match marker {}
14    }
15}
16
17macro_rules! ident_from_token {
18    ($token:ident) => {
19        impl From<Token![$token]> for Ident {
20            fn from(token: Token![$token]) -> Ident {
21                Ident::new(stringify!($token), token.span)
22            }
23        }
24    };
25}
26
27ident_from_token!(self);
28ident_from_token!(Self);
29ident_from_token!(super);
30ident_from_token!(crate);
31ident_from_token!(extern);
32
33impl From<Token![_]> for Ident {
34    fn from(token: Token![_]) -> Ident {
35        Ident::new("_", token.span)
36    }
37}
38
39pub(crate) fn xid_ok(symbol: &str) -> bool {
40    let mut chars = symbol.chars();
41    let first = chars.next().unwrap();
42    if !(first == '_' || first.is_ascii_alphabetic()) {
43        return false;
44    }
45    for ch in chars {
46        if !(ch == '_' || ch.is_ascii_alphanumeric()) {
47            return false;
48        }
49    }
50    true
51}
52
53#[cfg(feature = "parsing")]
54mod parsing {
55    use crate::buffer::Cursor;
56    use crate::error::Result;
57    use crate::parse::{Parse, ParseStream};
58    use crate::token::Token;
59    use proc_macro2::Ident;
60
61    fn accept_as_ident(ident: &Ident) -> bool {
62        match ident.to_string().as_str() {
63            "_" |
64            // Based on https://doc.rust-lang.org/1.65.0/reference/keywords.html
65            "abstract" | "as" | "async" | "await" | "become" | "box" | "break" |
66            "const" | "continue" | "crate" | "do" | "dyn" | "else" | "enum" |
67            "extern" | "false" | "final" | "fn" | "for" | "if" | "impl" | "in" |
68            "let" | "loop" | "macro" | "match" | "mod" | "move" | "mut" |
69            "override" | "priv" | "pub" | "ref" | "return" | "Self" | "self" |
70            "static" | "struct" | "super" | "trait" | "true" | "try" | "type" |
71            "typeof" | "unsafe" | "unsized" | "use" | "virtual" | "where" |
72            "while" | "yield" => false,
73            _ => true,
74        }
75    }
76
77    #[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
78    impl Parse for Ident {
79        fn parse(input: ParseStream) -> Result<Self> {
80            input.step(|cursor| {
81                if let Some((ident, rest)) = cursor.ident() {
82                    if accept_as_ident(&ident) {
83                        Ok((ident, rest))
84                    } else {
85                        Err(cursor.error(format_args!(
86                            "expected identifier, found keyword `{}`",
87                            ident,
88                        )))
89                    }
90                } else {
91                    Err(cursor.error("expected identifier"))
92                }
93            })
94        }
95    }
96
97    impl Token for Ident {
98        fn peek(cursor: Cursor) -> bool {
99            if let Some((ident, _rest)) = cursor.ident() {
100                accept_as_ident(&ident)
101            } else {
102                false
103            }
104        }
105
106        fn display() -> &'static str {
107            "identifier"
108        }
109    }
110}
syn/ident.rs

syn/
ident.rs
