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Parse try blocks with the try keyword instead of do catch placeholder

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This commit is contained in:
Scott McMurray 2018-07-21 20:59:44 -07:00
parent 1c906093f9
commit 9e64ce1799
31 changed files with 123 additions and 276 deletions
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22
src/libsyntax/parse/parser.rs
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@ -2386,11 +2386,10 @@ impl<'a> Parser<'a> {
BlockCheckMode::Unsafe(ast::UserProvided),
attrs);
}
if self.is_catch_expr() {
if self.is_try_block() {
let lo = self.span;
assert!(self.eat_keyword(keywords::Do));
assert!(self.eat_keyword(keywords::Catch));
return self.parse_catch_expr(lo, attrs);
assert!(self.eat_keyword(keywords::Try));
return self.parse_try_block(lo, attrs);
}
if self.eat_keyword(keywords::Return) {
if self.token.can_begin_expr() {
@ -3452,8 +3451,8 @@ impl<'a> Parser<'a> {
ExprKind::Async(capture_clause, ast::DUMMY_NODE_ID, body), attrs))
}
/// Parse a `do catch {...}` expression (`do catch` token already eaten)
fn parse_catch_expr(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>)
/// Parse a `try {...}` expression (`try` token already eaten)
fn parse_try_block(&mut self, span_lo: Span, mut attrs: ThinVec<Attribute>)
-> PResult<'a, P<Expr>>
{
let (iattrs, body) = self.parse_inner_attrs_and_block()?;
@ -4407,12 +4406,13 @@ impl<'a> Parser<'a> {
)
}
fn is_catch_expr(&mut self) -> bool {
self.token.is_keyword(keywords::Do) &&
self.look_ahead(1, |t| t.is_keyword(keywords::Catch)) &&
self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) &&
fn is_try_block(&mut self) -> bool {
self.token.is_keyword(keywords::Try) &&
self.look_ahead(1, |t| *t == token::OpenDelim(token::Brace)) &&
// prevent `while catch {} {}`, `if catch {} {} else {}`, etc.
self.span.edition() >= Edition::Edition2018 &&
// prevent `while try {} {}`, `if try {} {} else {}`, etc.
!self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
}