verbatim.rs

 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}