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LibJS: Add Reference class to represent a base.property reference

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Expression nodes can now be asked to produce a Reference. We then use
this to implement the "delete" operator without downcasting the child
node to a MemberExpression manually.
This commit is contained in:
Andreas Kling 2020-04-27 12:10:16 +02:00
parent 3a12a8a348
commit 67b8e6fc5b
5 changed files with 105 additions and 9 deletions
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35
Libraries/LibJS/AST.cpp
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@ -37,6 +37,7 @@
#include <LibJS/Runtime/MarkedValueList.h>
#include <LibJS/Runtime/NativeFunction.h>
#include <LibJS/Runtime/PrimitiveString.h>
#include <LibJS/Runtime/Reference.h>
#include <LibJS/Runtime/ScriptFunction.h>
#include <LibJS/Runtime/Value.h>
#include <stdio.h>
@ -376,21 +377,37 @@ Value LogicalExpression::execute(Interpreter& interpreter) const
ASSERT_NOT_REACHED();
}
Reference Expression::to_reference(Interpreter&) const
{
return {};
}
Reference MemberExpression::to_reference(Interpreter& interpreter) const
{
auto object_value = m_object->execute(interpreter);
if (object_value.is_empty())
return {};
auto* object = object_value.to_object(interpreter.heap());
if (!object)
return {};
auto property_name = computed_property_name(interpreter);
if (!property_name.is_valid())
return {};
return { object, property_name };
}
Value UnaryExpression::execute(Interpreter& interpreter) const
{
if (m_op == UnaryOp::Delete) {
if (!m_lhs->is_member_expression())
return Value(true);
auto object_value = static_cast<const MemberExpression&>(*m_lhs).object().execute(interpreter);
auto reference = m_lhs->to_reference(interpreter);
if (interpreter.exception())
return {};
auto* object = object_value.to_object(interpreter.heap());
if (!object)
if (reference.is_unresolvable())
return Value(true);
auto* base_object = reference.base().to_object(interpreter.heap());
if (!base_object)
return {};
auto property_name = static_cast<const MemberExpression&>(*m_lhs).computed_property_name(interpreter);
if (!property_name.is_valid())
return {};
return object->delete_property(property_name);
return base_object->delete_property(reference.name());
}
auto lhs_result = m_lhs->execute(interpreter);