Function between

impl/src/fmt.rs:299–323

(begin: ParseStream<'a>, end: ParseStream<'a>)

}

fn between<'a>(begin: ParseStream<'a>, end: ParseStream<'a>) -> TokenStream {
    let end = end.cursor();
    let mut cursor = begin.cursor();
    let mut tokens = TokenStream::new();

    while cursor < end {
        let (tt, next) = cursor.token_tree().unwrap();

        if end < next {
            if let Some((inside, _span, _after)) = cursor.group(Delimiter::None) {
                cursor = inside;
                continue;
            }
            if tokens.is_empty() {
                tokens.extend(iter::once(tt));
            }
            break;
        }

        tokens.extend(iter::once(tt));
        cursor = next;
    }

    tokens
}