projects/linux·blob master · refs

35 lines · 1.2 KiB

1// SPDX-License-Identifier: Apache-2.0 OR MIT
2
3use crate::parse::ParseStream;
4use proc_macro2::{Delimiter, TokenStream};
5use std::cmp::Ordering;
6use std::iter;
7
8pub(crate) fn between<'a>(begin: ParseStream<'a>, end: ParseStream<'a>) -> TokenStream {
9 let end = end.cursor();
10 let mut cursor = begin.cursor();
11 assert!(crate::buffer::same_buffer(end, cursor));
12
13 let mut tokens = TokenStream::new();
14 while cursor != end {
15 let (tt, next) = cursor.token_tree().unwrap();
16
17 if crate::buffer::cmp_assuming_same_buffer(end, next) == Ordering::Less {
18 // A syntax node can cross the boundary of a None-delimited group
19 // due to such groups being transparent to the parser in most cases.
20 // Any time this occurs the group is known to be semantically
21 // irrelevant. https://github.com/dtolnay/syn/issues/1235
22 if let Some((inside, _span, after)) = cursor.group(Delimiter::None) {
23 assert!(next == after);
24 cursor = inside;
25 continue;
26 } else {
27 panic!("verbatim end must not be inside a delimited group");
28 }
29 }
30
31 tokens.extend(iter::once(tt));
32 cursor = next;
33 }
34 tokens
35}