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Move path parsing earlier.

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It's a hot enough path that moving it slightly earlier gives a tiny but
easy speedup.
This commit is contained in:
Nicholas Nethercote
2019-09-03 17:21:58 +10:00
parent dfd43f0fdd
commit 8c74eb7790
1 changed files with 30 additions and 26 deletions
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56
src/libsyntax/parse/parser/expr.rs
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@@ -889,6 +889,36 @@ impl<'a> Parser<'a> {
hi = path.span;
return Ok(self.mk_expr(lo.to(hi), ExprKind::Path(Some(qself), path), attrs));
}
if self.token.is_path_start() {
let path = self.parse_path(PathStyle::Expr)?;
// `!`, as an operator, is prefix, so we know this isn't that
if self.eat(&token::Not) {
// MACRO INVOCATION expression
let (delim, tts) = self.expect_delimited_token_tree()?;
hi = self.prev_span;
ex = ExprKind::Mac(Mac {
path,
tts,
delim,
span: lo.to(hi),
prior_type_ascription: self.last_type_ascription,
});
} else if self.check(&token::OpenDelim(token::Brace)) {
if let Some(expr) = self.maybe_parse_struct_expr(lo, &path, &attrs) {
return expr;
} else {
hi = path.span;
ex = ExprKind::Path(None, path);
}
} else {
hi = path.span;
ex = ExprKind::Path(None, path);
}
let expr = self.mk_expr(lo.to(hi), ex, attrs);
return self.maybe_recover_from_bad_qpath(expr, true);
}
if self.check_keyword(kw::Move) || self.check_keyword(kw::Static) {
return self.parse_lambda_expr(attrs);
}
@@ -1007,32 +1037,6 @@ impl<'a> Parser<'a> {
let (await_hi, e_kind) = self.parse_incorrect_await_syntax(lo, self.prev_span)?;
hi = await_hi;
ex = e_kind;
} else if self.token.is_path_start() {
let path = self.parse_path(PathStyle::Expr)?;
// `!`, as an operator, is prefix, so we know this isn't that
if self.eat(&token::Not) {
// MACRO INVOCATION expression
let (delim, tts) = self.expect_delimited_token_tree()?;
hi = self.prev_span;
ex = ExprKind::Mac(Mac {
path,
tts,
delim,
span: lo.to(hi),
prior_type_ascription: self.last_type_ascription,
});
} else if self.check(&token::OpenDelim(token::Brace)) {
if let Some(expr) = self.maybe_parse_struct_expr(lo, &path, &attrs) {
return expr;
} else {
hi = path.span;
ex = ExprKind::Path(None, path);
}
} else {
hi = path.span;
ex = ExprKind::Path(None, path);
}
} else {
if !self.unclosed_delims.is_empty() && self.check(&token::Semi) {
// Don't complain about bare semicolons after unclosed braces