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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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4
compiler/rustc_ast/src/tokenstream.rs
View File

@ -403,8 +403,8 @@ impl Cursor {
self.index = index; self.index = index;
} }
pub fn look_ahead(&self, n: usize) -> Option<TokenTree> { pub fn look_ahead(&self, n: usize) -> Option<&TokenTree> {
self.stream.0[self.index..].get(n).map(|(tree, _)| tree.clone()) self.stream.0[self.index..].get(n).map(|(tree, _)| tree)
} }
} }

11
compiler/rustc_expand/src/proc_macro_server.rs
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@ -47,13 +47,18 @@ impl ToInternal<token::DelimToken> for Delimiter {
} }
} }
impl FromInternal<(TreeAndJoint, Option<tokenstream::TokenTree>, &'_ ParseSess, &'_ mut Vec<Self>)> impl
for TokenTree<Group, Punct, Ident, Literal> FromInternal<(
TreeAndJoint,
Option<&'_ tokenstream::TokenTree>,
&'_ ParseSess,
&'_ mut Vec<Self>,
)> for TokenTree<Group, Punct, Ident, Literal>
{ {
fn from_internal( fn from_internal(
((tree, is_joint), look_ahead, sess, stack): ( ((tree, is_joint), look_ahead, sess, stack): (
TreeAndJoint, TreeAndJoint,
Option<tokenstream::TokenTree>, Option<&tokenstream::TokenTree>,
&ParseSess, &ParseSess,
&mut Vec<Self>, &mut Vec<Self>,
), ),

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

@ -822,15 +822,15 @@ impl<'a> Parser<'a> {
} }
let frame = &self.token_cursor.frame; 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 { Some(tree) => match tree {
TokenTree::Token(token) => token, TokenTree::Token(token) => looker(token),
TokenTree::Delimited(dspan, delim, _) => { 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. /// Returns whether any of the given keywords are `dist` tokens ahead of the current one.