bjoernager/rust
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rustc: Add ternary operator. Closes #565

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The implementation is so simple it might be considered cheating: at almost
every step the expr_ternary is just converted to expr_if.
This commit is contained in:
Brian Anderson 2011-06-23 15:15:50 -07:00
parent 5495ad17d1
commit 05c0216654
9 changed files with 110 additions and 2 deletions
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16
src/comp/front/parser.rs
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@ -1071,6 +1071,20 @@ fn parse_prefix_expr(&parser p) -> @ast::expr {
ret mk_expr(p, lo, hi, ex);
}
fn parse_ternary(&parser p) -> @ast::expr {
auto cond_expr = parse_binops(p);
if (p.peek() == token::QUES) {
p.bump();
auto then_expr = parse_expr(p);
expect(p, token::COLON);
auto else_expr = parse_expr(p);
ret mk_expr(p, cond_expr.span.lo, else_expr.span.hi,
ast::expr_ternary(cond_expr, then_expr, else_expr));
} else {
ret cond_expr;
}
}
type op_spec = rec(token::token tok, ast::binop op, int prec);
@ -1128,7 +1142,7 @@ fn parse_more_binops(&parser p, @ast::expr lhs, int min_prec) -> @ast::expr {
fn parse_assign_expr(&parser p) -> @ast::expr {
auto lo = p.get_lo_pos();
auto lhs = parse_binops(p);
auto lhs = parse_ternary(p);
alt (p.peek()) {
case (token::EQ) {
p.bump();