1use crate::parse::ParseStream;
2use proc_macro2::{Delimiter, TokenStream};
3use std::cmp::Ordering;
4use std::iter;
5
6pub(crate) fn between<'a>(begin: ParseStream<'a>, end: ParseStream<'a>) -> TokenStream {
7 let end = end.cursor();
8 let mut cursor = begin.cursor();
9 assert!(crate::buffer::same_buffer(end, cursor));
10
11 let mut tokens = TokenStream::new();
12 while cursor != end {
13 let (tt, next) = cursor.token_tree().unwrap();
14
15 if crate::buffer::cmp_assuming_same_buffer(end, next) == Ordering::Less {
16 // A syntax node can cross the boundary of a None-delimited group
17 // due to such groups being transparent to the parser in most cases.
18 // Any time this occurs the group is known to be semantically
19 // irrelevant. https://github.com/dtolnay/syn/issues/1235
20 if let Some((inside, _span, after)) = cursor.group(Delimiter::None) {
21 assert!(next == after);
22 cursor = inside;
23 continue;
24 } else {
25 panic!("verbatim end must not be inside a delimited group");
26 }
27 }
28
29 tokens.extend(iter::once(tt));
30 cursor = next;
31 }
32 tokens
33}
34