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}