bjoernager/rust
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Optimize Cursor::look_ahead

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Cloning a tt is cheap, but not free (there's Arc inside).
This commit is contained in:
Aleksey Kladov 2020-09-03 23:26:59 +02:00
parent 850c3219fb
commit 09d3db2e59
3 changed files with 15 additions and 10 deletions
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10
compiler/rustc_parse/src/parser/mod.rs
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@ -822,15 +822,15 @@ impl<'a> Parser<'a> {
}
let frame = &self.token_cursor.frame;
looker(&match frame.tree_cursor.look_ahead(dist - 1) {
match frame.tree_cursor.look_ahead(dist - 1) {
Some(tree) => match tree {
TokenTree::Token(token) => token,
TokenTree::Token(token) => looker(token),
TokenTree::Delimited(dspan, delim, _) => {
Token::new(token::OpenDelim(delim), dspan.open)
looker(&Token::new(token::OpenDelim(delim.clone()), dspan.open))
}
},
None => Token::new(token::CloseDelim(frame.delim), frame.span.close),
})
None => looker(&Token::new(token::CloseDelim(frame.delim), frame.span.close)),
}
}
/// Returns whether any of the given keywords are `dist` tokens ahead of the current one.