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syntax: implement labelled breaks for for.

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`for` desugars to `loop` so it is trivial to just desugar to `loop` while
retaining any label.
This commit is contained in:
Huon Wilson
2013-09-08 22:08:01 +10:00
parent b609d022c4
commit 07351b44c6
9 changed files with 32 additions and 16 deletions
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15
src/libsyntax/parse/parser.rs
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@@ -1771,7 +1771,7 @@ impl Parser {
} else if self.eat_keyword(keywords::If) {
return self.parse_if_expr();
} else if self.eat_keyword(keywords::For) {
return self.parse_for_expr();
return self.parse_for_expr(None);
} else if self.eat_keyword(keywords::Do) {
return self.parse_sugary_call_expr(lo, ~"do", DoSugar,
ExprDoBody);
@@ -1781,8 +1781,13 @@ impl Parser {
let lifetime = self.get_lifetime(&*self.token);
self.bump();
self.expect(&token::COLON);
self.expect_keyword(keywords::Loop);
return self.parse_loop_expr(Some(lifetime));
if self.eat_keyword(keywords::For) {
return self.parse_for_expr(Some(lifetime))
} else if self.eat_keyword(keywords::Loop) {
return self.parse_loop_expr(Some(lifetime))
} else {
self.fatal("expected `for` or `loop` after a label")
}
} else if self.eat_keyword(keywords::Loop) {
return self.parse_loop_expr(None);
} else if self.eat_keyword(keywords::Match) {
@@ -2467,7 +2472,7 @@ impl Parser {
}
// parse a 'for' .. 'in' expression ('for' token already eaten)
pub fn parse_for_expr(&self) -> @Expr {
pub fn parse_for_expr(&self, opt_ident: Option<ast::Ident>) -> @Expr {
// Parse: `for <src_pat> in <src_expr> <src_loop_block>`
let lo = self.last_span.lo;
@@ -2477,7 +2482,7 @@ impl Parser {
let loop_block = self.parse_block();
let hi = self.span.hi;
self.mk_expr(lo, hi, ExprForLoop(pat, expr, loop_block))
self.mk_expr(lo, hi, ExprForLoop(pat, expr, loop_block, opt_ident))
}