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syntax: Allow any block-like expr to be used as alt arm w/o comma separator

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This commit is contained in:
Brian Anderson 2012-08-01 16:16:53 -07:00
parent fd17d347b0
commit 507fba57d1
5 changed files with 99 additions and 34 deletions
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45
src/libsyntax/parse/parser.rs
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@ -1477,9 +1477,10 @@ class parser {
// For distingishing between record literals and blocks
fn looking_at_record_literal() -> bool {
let lookahead = self.look_ahead(1);
self.token_is_keyword(~"mut", lookahead) ||
(is_plain_ident(lookahead) &&
self.look_ahead(2) == token::COLON)
self.token == token::LBRACE &&
(self.token_is_keyword(~"mut", lookahead) ||
(is_plain_ident(lookahead) &&
self.look_ahead(2) == token::COLON))
}
fn parse_record_literal() -> expr_ {
@ -1518,26 +1519,30 @@ class parser {
let pats = self.parse_pats();
let mut guard = none;
if self.eat_keyword(~"if") { guard = some(self.parse_expr()); }
let blk = if self.token != token::FAT_ARROW {
self.parse_block()
let expr = if self.token != token::FAT_ARROW {
self.parse_block_expr(self.last_span.lo, default_blk)
} else {
self.bump();
if self.token == token::LBRACE
&& !self.looking_at_record_literal() {
self.parse_block()
} else {
let expr = self.parse_expr();
if self.token != token::RBRACE {
self.expect(token::COMMA);
}
{node: {view_items: ~[],
stmts: ~[],
expr: some(expr),
id: self.get_id(),
rules: default_blk},
span: expr.span}
}
self.parse_expr_res(RESTRICT_STMT_EXPR)
};
let require_comma =
classify::expr_requires_semi_to_be_stmt(expr)
&& self.token != token::RBRACE;
if require_comma {
self.expect(token::COMMA);
} else {
self.eat(token::COMMA);
}
let blk = {node: {view_items: ~[],
stmts: ~[],
expr: some(expr),
id: self.get_id(),
rules: default_blk},
span: expr.span};
vec::push(arms, {pats: pats, guard: guard, body: blk});
}
let mut hi = self.span.hi;