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LibJS: Improve UpdateExpression::execute()

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- Let undefined variables throw a ReferenceError by using
  Identifier::execute() rather than doing variable lookup manually and
  ASSERT()ing
- Coerce value to number rather than ASSERT()ing
- Make code DRY
- Add tests
This commit is contained in:
Linus Groh 2020-04-21 23:27:11 +01:00 • committed by Andreas Kling
parent b2305cb67d
commit a1b820b11c
2 changed files with 63 additions and 11 deletions
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20
Libraries/LibJS/AST.cpp
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@ -775,11 +775,10 @@ Value UpdateExpression::execute(Interpreter& interpreter) const
{
ASSERT(m_argument->is_identifier());
auto name = static_cast<const Identifier&>(*m_argument).string();
auto previous_variable = interpreter.get_variable(name);
ASSERT(previous_variable.has_value());
auto previous_value = previous_variable.value();
ASSERT(previous_value.is_number());
auto old_value = m_argument->execute(interpreter);
if (interpreter.exception())
return {};
old_value = old_value.to_number();
int op_result = 0;
switch (m_op) {
@ -789,14 +788,13 @@ Value UpdateExpression::execute(Interpreter& interpreter) const
case UpdateOp::Decrement:
op_result = -1;
break;
default:
ASSERT_NOT_REACHED();
}
interpreter.set_variable(name, Value(previous_value.as_double() + op_result));
if (m_prefixed)
return JS::Value(previous_value.as_double() + op_result);
return previous_value;
auto new_value = Value(old_value.as_double() + op_result);
interpreter.set_variable(name, new_value);
return m_prefixed ? new_value : old_value;
}
void AssignmentExpression::dump(int indent) const