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extract is_certainly_not_a_block

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This commit is contained in:
Mazdak Farrokhzad 2019-12-04 04:31:44 +01:00
parent 66b8ae4bce
commit f6e2bdc341
1 changed files with 16 additions and 16 deletions
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32
src/librustc_parse/parser/expr.rs
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@ -1721,6 +1721,21 @@ impl<'a> Parser<'a> {
)) ))
} }
fn is_certainly_not_a_block(&self) -> bool {
self.look_ahead(1, |t| t.is_ident())
&& (
// `{ ident, ` cannot start a block.
self.look_ahead(2, |t| t == &token::Comma)
|| self.look_ahead(2, |t| t == &token::Colon)
&& (
// `{ ident: token, ` cannot start a block.
self.look_ahead(4, |t| t == &token::Comma) ||
// `{ ident: ` cannot start a block unless it's a type ascription `ident: Type`.
self.look_ahead(3, |t| !t.can_begin_type())
)
)
}
fn maybe_parse_struct_expr( fn maybe_parse_struct_expr(
&mut self, &mut self,
lo: Span, lo: Span,
@ -1728,22 +1743,7 @@ impl<'a> Parser<'a> {
attrs: &AttrVec, attrs: &AttrVec,
) -> Option<PResult<'a, P<Expr>>> { ) -> Option<PResult<'a, P<Expr>>> {
let struct_allowed = !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL); let struct_allowed = !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
let certainly_not_a_block = || { if struct_allowed || self.is_certainly_not_a_block() {
self.look_ahead(1, |t| t.is_ident())
&& (
// `{ ident, ` cannot start a block.
self.look_ahead(2, |t| t == &token::Comma)
|| self.look_ahead(2, |t| t == &token::Colon)
&& (
// `{ ident: token, ` cannot start a block.
self.look_ahead(4, |t| t == &token::Comma) ||
// `{ ident: ` cannot start a block unless it's a type ascription `ident: Type`.
self.look_ahead(3, |t| !t.can_begin_type())
)
)
};
if struct_allowed || certainly_not_a_block() {
// This is a struct literal, but we don't can't accept them here. // This is a struct literal, but we don't can't accept them here.
let expr = self.parse_struct_expr(lo, path.clone(), attrs.clone()); let expr = self.parse_struct_expr(lo, path.clone(), attrs.clone());
if let (Ok(expr), false) = (&expr, struct_allowed) { if let (Ok(expr), false) = (&expr, struct_allowed) {