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    #[cfg(feature = "parsing")]
    use crate::buffer::Cursor;
    #[cfg(feature = "parsing")]
    use crate::lookahead;
    #[cfg(feature = "parsing")]
    use crate::parse::{Parse, ParseStream, Result};
    #[cfg(feature = "parsing")]
    use crate::token::Token;
    use unicode_xid::UnicodeXID;

    pub use proc_macro2::Ident;

    #[cfg(feature = "parsing")]
    #[doc(hidden)]
    #[allow(non_snake_case)]
    pub fn Ident(marker: lookahead::TokenMarker) -> Ident {
        match marker {}
    }

    #[cfg(feature = "parsing")]
    fn accept_as_ident(ident: &Ident) -> bool {
        match ident.to_string().as_str() {
            "_" |
            // Based on https://doc.rust-lang.org/grammar.html#keywords
            // and https://github.com/rust-lang/rfcs/blob/master/text/2421-unreservations-2018.md
            // and https://github.com/rust-lang/rfcs/blob/master/text/2420-unreserve-proc.md
            "abstract" | "as" | "become" | "box" | "break" | "const" | "continue" |
            "crate" | "do" | "else" | "enum" | "extern" | "false" | "final" | "fn" |
            "for" | "if" | "impl" | "in" | "let" | "loop" | "macro" | "match" |
            "mod" | "move" | "mut" | "override" | "priv" | "pub" | "ref" |
            "return" | "Self" | "self" | "static" | "struct" | "super" | "trait" |
            "true" | "type" | "typeof" | "unsafe" | "unsized" | "use" | "virtual" |
            "where" | "while" | "yield" => false,
            _ => true,
        }
    }

    #[cfg(feature = "parsing")]
    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
    impl Parse for Ident {
        fn parse(input: ParseStream) -> Result<Self> {
            input.step(|cursor| {
                if let Some((ident, rest)) = cursor.ident() {
                    if accept_as_ident(&ident) {
                        return Ok((ident, rest));
                    }
                }
                Err(cursor.error("expected identifier"))
            })
        }
    }

    #[cfg(feature = "parsing")]
    impl Token for Ident {
        fn peek(cursor: Cursor) -> bool {
            if let Some((ident, _rest)) = cursor.ident() {
                accept_as_ident(&ident)
            } else {
                false
            }
        }

        fn display() -> &'static str {
            "identifier"
        }
    }

    macro_rules! ident_from_token {
        ($token:ident) => {
            impl From<Token![$token]> for Ident {
                fn from(token: Token![$token]) -> Ident {
                    Ident::new(stringify!($token), token.span)
                }
            }
        };
    }

    ident_from_token!(self);
    ident_from_token!(Self);
    ident_from_token!(super);
    ident_from_token!(crate);
    ident_from_token!(extern);

    impl From<Token![_]> for Ident {
        fn from(token: Token![_]) -> Ident {
            Ident::new("_", token.span)
        }
    }

    pub fn xid_ok(symbol: &str) -> bool {
        let mut chars = symbol.chars();
        let first = chars.next().unwrap();
        if !(UnicodeXID::is_xid_start(first) || first == '_') {
            return false;
        }
        for ch in chars {
            if !UnicodeXID::is_xid_continue(ch) {
                return false;
            }
        }
        true
    }