Function parse_token_expr

impl/src/attr.rs:196–300

(input: ParseStream, mut begin_expr: bool)

}

fn parse_token_expr(input: ParseStream, mut begin_expr: bool) -> Result<TokenStream> {
    let mut tokens = Vec::new();
    while !input.is_empty() {
        if input.peek(token::Group) {
            let group: TokenTree = input.parse()?;
            tokens.push(group);
            begin_expr = false;
            continue;
        }

        if begin_expr && input.peek(Token![.]) {
            if input.peek2(Ident) {
                input.parse::<Token![.]>()?;
                begin_expr = false;
                continue;
            } else if input.peek2(LitInt) {
                input.parse::<Token![.]>()?;
                let int: Index = input.parse()?;
                tokens.push({
                    let ident = format_ident!("_{}", int.index, span = int.span);
                    TokenTree::Ident(ident)
                });
                begin_expr = false;
                continue;
            } else if input.peek2(LitFloat) {
                let ahead = input.fork();
                ahead.parse::<Token![.]>()?;
                let float: LitFloat = ahead.parse()?;
                let repr = float.to_string();
                let mut indices = repr.split('.').map(syn::parse_str::<Index>);
                if let (Some(Ok(first)), Some(Ok(second)), None) =
                    (indices.next(), indices.next(), indices.next())
                {
                    input.advance_to(&ahead);
                    tokens.push({
                        let ident = format_ident!("_{}", first, span = float.span());
                        TokenTree::Ident(ident)
                    });
                    tokens.push({
                        let mut punct = Punct::new('.', Spacing::Alone);
                        punct.set_span(float.span());
                        TokenTree::Punct(punct)
                    });
                    tokens.push({
                        let mut literal = Literal::u32_unsuffixed(second.index);
                        literal.set_span(float.span());
                        TokenTree::Literal(literal)
                    });
                    begin_expr = false;
                    continue;
                }
            }
        }

        begin_expr = input.peek(Token![break])
            || input.peek(Token![continue])
            || input.peek(Token![if])
            || input.peek(Token![in])