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Introduced Cursor::next_with_spacing_ref.

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This lets us clone just the parts within a `TokenTree` that need
cloning, rather than the entire thing. This is a surprisingly large
performance win, up to 4% on `async-std-1.10.0`.
This commit is contained in:
Nicholas Nethercote 2022-04-21 13:49:40 +10:00
parent cc4e3443ec
commit 643e9f707e
2 changed files with 13 additions and 5 deletions
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8
compiler/rustc_ast/src/tokenstream.rs
View File

@ -583,6 +583,14 @@ impl Cursor {
})
}
#[inline]
pub fn next_with_spacing_ref(&mut self) -> Option<&TreeAndSpacing> {
self.stream.0.get(self.index).map(|tree| {
self.index += 1;
tree
})
}
pub fn index(&self) -> usize {
self.index
}

10
compiler/rustc_parse/src/parser/mod.rs
View File

@ -267,17 +267,17 @@ impl TokenCursor {
// FIXME: we currently don't return `NoDelim` open/close delims. To fix #67062 we will
// need to, whereupon the `delim != DelimToken::NoDelim` conditions below can be
// removed, as well as the loop.
if let Some((tree, spacing)) = self.frame.tree_cursor.next_with_spacing() {
if let Some((tree, spacing)) = self.frame.tree_cursor.next_with_spacing_ref() {
match tree {
TokenTree::Token(token) => match (desugar_doc_comments, &token) {
&TokenTree::Token(ref token) => match (desugar_doc_comments, token) {
(true, &Token { kind: token::DocComment(_, attr_style, data), span }) => {
return self.desugar(attr_style, data, span);
}
_ => return (token, spacing),
_ => return (token.clone(), *spacing),
},
TokenTree::Delimited(sp, delim, tts) => {
&TokenTree::Delimited(sp, delim, ref tts) => {
// Set `open_delim` to true here because we deal with it immediately.
let frame = TokenCursorFrame::new(sp, delim, tts);
let frame = TokenCursorFrame::new(sp, delim, tts.clone());
self.stack.push(mem::replace(&mut self.frame, frame));
if delim != DelimToken::NoDelim {
return (Token::new(token::OpenDelim(delim), sp.open), Spacing::Alone);