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Better semantics for the ?: ternary operator.

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This commit is contained in:
John Wiegley 2009-02-08 03:01:51 -04:00
parent aebfc92a4d
commit 7594639581
2 changed files with 41 additions and 6 deletions
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33
src/op.cc
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@ -201,6 +201,20 @@ value_t expr_t::op_t::calc(scope_t& scope, ptr_op_t * context)
result = right()->calc(scope, context);
break;
case O_QUERY:
assert(right());
assert(right()->kind == O_COLON);
if (value_t temp = left()->calc(scope, context))
result = right()->left()->calc(scope, context);
else
result = right()->right()->calc(scope, context);
break;
case O_COLON:
assert(! "We should never calculate an O_COLON operator");
break;
case O_COMMA: {
value_t temp(left()->calc(scope, context));
@ -379,6 +393,22 @@ bool expr_t::op_t::print(std::ostream& out, const context_t& context) const
out << ")";
break;
case O_QUERY:
if (left() && left()->print(out, context))
found = true;
out << " ? ";
if (has_right() && right()->print(out, context))
found = true;
break;
case O_COLON:
if (left() && left()->print(out, context))
found = true;
out << " : ";
if (has_right() && right()->print(out, context))
found = true;
break;
case O_COMMA:
if (left() && left()->print(out, context))
found = true;
@ -476,6 +506,9 @@ void expr_t::op_t::dump(std::ostream& out, const int depth) const
case O_AND: out << "O_AND"; break;
case O_OR: out << "O_OR"; break;
case O_QUERY: out << "O_QUERY"; break;
case O_COLON: out << "O_COLON"; break;
case O_COMMA: out << "O_COMMA"; break;
case LAST:

14
src/parser.cc
View file

@ -340,7 +340,7 @@ expr_t::parser_t::parse_querycolon_expr(std::istream& in,
if (tok.kind == token_t::QUERY) {
ptr_op_t prev(node);
node = new op_t(op_t::O_AND);
node = new op_t(op_t::O_QUERY);
node->set_left(prev);
node->set_right(parse_or_expr(in, tflags));
if (! node->right())
@ -351,13 +351,15 @@ expr_t::parser_t::parse_querycolon_expr(std::istream& in,
if (next_tok.kind != token_t::COLON)
next_tok.expected(':');
prev = node;
node = new op_t(op_t::O_OR);
node->set_left(prev);
node->set_right(parse_or_expr(in, tflags));
if (! node->right())
prev = node->right();
ptr_op_t subnode = new op_t(op_t::O_COLON);
subnode->set_left(prev);
subnode->set_right(parse_or_expr(in, tflags));
if (! subnode->right())
throw_(parse_error,
tok.symbol << " operator not followed by argument");
node->set_right(subnode);
} else {
push_token(tok);
}