syn/
ident.rs

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1#[cfg(feature = "parsing")]
2use crate::buffer::Cursor;
3#[cfg(feature = "parsing")]
4use crate::lookahead;
5#[cfg(feature = "parsing")]
6use crate::parse::{Parse, ParseStream, Result};
7#[cfg(feature = "parsing")]
8use crate::token::Token;
9
10pub use proc_macro2::Ident;
11
12#[cfg(feature = "parsing")]
13#[doc(hidden)]
14#[allow(non_snake_case)]
15pub fn Ident(marker: lookahead::TokenMarker) -> Ident {
16    match marker {}
17}
18
19#[cfg(feature = "parsing")]
20fn accept_as_ident(ident: &Ident) -> bool {
21    match ident.to_string().as_str() {
22        "_" |
23        // Based on https://doc.rust-lang.org/grammar.html#keywords
24        // and https://github.com/rust-lang/rfcs/blob/master/text/2421-unreservations-2018.md
25        // and https://github.com/rust-lang/rfcs/blob/master/text/2420-unreserve-proc.md
26        "abstract" | "as" | "become" | "box" | "break" | "const" | "continue" |
27        "crate" | "do" | "else" | "enum" | "extern" | "false" | "final" | "fn" |
28        "for" | "if" | "impl" | "in" | "let" | "loop" | "macro" | "match" |
29        "mod" | "move" | "mut" | "override" | "priv" | "pub" | "ref" |
30        "return" | "Self" | "self" | "static" | "struct" | "super" | "trait" |
31        "true" | "type" | "typeof" | "unsafe" | "unsized" | "use" | "virtual" |
32        "where" | "while" | "yield" => false,
33        _ => true,
34    }
35}
36
37#[cfg(feature = "parsing")]
38#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
39impl Parse for Ident {
40    fn parse(input: ParseStream) -> Result<Self> {
41        input.step(|cursor| {
42            if let Some((ident, rest)) = cursor.ident() {
43                if accept_as_ident(&ident) {
44                    return Ok((ident, rest));
45                }
46            }
47            Err(cursor.error("expected identifier"))
48        })
49    }
50}
51
52#[cfg(feature = "parsing")]
53impl Token for Ident {
54    fn peek(cursor: Cursor) -> bool {
55        if let Some((ident, _rest)) = cursor.ident() {
56            accept_as_ident(&ident)
57        } else {
58            false
59        }
60    }
61
62    fn display() -> &'static str {
63        "identifier"
64    }
65}
66
67macro_rules! ident_from_token {
68    ($token:ident) => {
69        impl From<Token![$token]> for Ident {
70            fn from(token: Token![$token]) -> Ident {
71                Ident::new(stringify!($token), token.span)
72            }
73        }
74    };
75}
76
77ident_from_token!(self);
78ident_from_token!(Self);
79ident_from_token!(super);
80ident_from_token!(crate);
81ident_from_token!(extern);
82
83impl From<Token![_]> for Ident {
84    fn from(token: Token![_]) -> Ident {
85        Ident::new("_", token.span)
86    }
87}
88
89pub fn xid_ok(symbol: &str) -> bool {
90    let mut chars = symbol.chars();
91    let first = chars.next().unwrap();
92    if !(first == '_' || unicode_ident::is_xid_start(first)) {
93        return false;
94    }
95    for ch in chars {
96        if !unicode_ident::is_xid_continue(ch) {
97            return false;
98        }
99    }
100    true
101}
syn/ident.rs

syn/
ident.rs
