rust-lang/rust
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

Auto merge of #145348 - nnethercote:parse_token_tree-speedup-for-uom, r=petrochenkov

Browse Source 
Sometimes skip over tokens in `parse_token_tree`.

r? `@petrochenkov`
This commit is contained in:
bors
2025-08-20 09:01:41 +00:00
parent 22a86f8280 145b84721a
commit bec747418c
2 changed files with 23 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
compiler/rustc_parse/src/parser/mod.rs
View File

@@ -1388,15 +1388,26 @@ impl<'a> Parser<'a> {
// matching `CloseDelim` we are *after* the delimited sequence,
// i.e. at depth `d - 1`.
let target_depth = self.token_cursor.stack.len() - 1;
loop {
// Advance one token at a time, so `TokenCursor::next()`
// can capture these tokens if necessary.
if let Capturing::No = self.capture_state.capturing {
// We are not capturing tokens, so skip to the end of the
// delimited sequence. This is a perf win when dealing with
// declarative macros that pass large `tt` fragments through
// multiple rules, as seen in the uom-0.37.0 crate.
self.token_cursor.curr.bump_to_end();
self.bump();
if self.token_cursor.stack.len() == target_depth {
debug_assert!(self.token.kind.close_delim().is_some());
break;
debug_assert_eq!(self.token_cursor.stack.len(), target_depth);
} else {
loop {
// Advance one token at a time, so `TokenCursor::next()`
// can capture these tokens if necessary.
self.bump();
if self.token_cursor.stack.len() == target_depth {
break;
}
}
}
debug_assert!(self.token.kind.close_delim().is_some());
// Consume close delimiter
self.bump();