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LibJS: Initial class implementation; allow super expressions in object

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literal methods; add EnvrionmentRecord fields and methods to
LexicalEnvironment

Adding EnvrionmentRecord's fields and methods lets us throw an exception
when |this| is not initialized, which occurs when the super constructor
in a derived class has not yet been called, or when |this| has already
been initialized (the super constructor was already called).
This commit is contained in:
Jack Karamanian 2020-06-08 13:31:21 -05:00 • committed by Andreas Kling
parent a535d58cac
commit 7533fd8b02
18 changed files with 967 additions and 92 deletions
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77
Libraries/LibJS/Interpreter.cpp
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@ -59,7 +59,10 @@ Value Interpreter::run(GlobalObject& global_object, const Statement& statement,
CallFrame global_call_frame;
global_call_frame.this_value = &global_object;
global_call_frame.function_name = "(global execution context)";
global_call_frame.environment = heap().allocate<LexicalEnvironment>(global_object);
global_call_frame.environment = heap().allocate<LexicalEnvironment>(global_object, LexicalEnvironment::EnvironmentRecordType::Global);
global_call_frame.environment->bind_this_value(&global_object);
if (exception())
return {};
m_call_stack.append(move(global_call_frame));
}
}
@ -226,6 +229,10 @@ Value Interpreter::call(Function& function, Value this_value, Optional<MarkedVal
if (arguments.has_value())
call_frame.arguments.append(arguments.value().values());
call_frame.environment = function.create_environment();
ASSERT(call_frame.environment->this_binding_status() == LexicalEnvironment::ThisBindingStatus::Uninitialized);
call_frame.environment->bind_this_value(call_frame.this_value);
auto result = function.call(*this);
pop_call_frame();
return result;
@ -235,29 +242,59 @@ Value Interpreter::construct(Function& function, Function& new_target, Optional<
{
auto& call_frame = push_call_frame();
call_frame.function_name = function.name();
call_frame.arguments = function.bound_arguments();
if (arguments.has_value())
call_frame.arguments = arguments.value().values();
call_frame.arguments.append(arguments.value().values());
call_frame.environment = function.create_environment();
auto* new_object = Object::create_empty(*this, global_object);
auto prototype = new_target.get("prototype");
if (exception())
return {};
if (prototype.is_object()) {
new_object->set_prototype(&prototype.as_object());
current_environment()->set_new_target(&new_target);
Object* new_object = nullptr;
if (function.constructor_kind() == Function::ConstructorKind::Base) {
new_object = Object::create_empty(*this, global_object);
current_environment()->bind_this_value(new_object);
if (exception())
return {};
auto prototype = new_target.get("prototype");
if (exception())
return {};
if (prototype.is_object()) {
new_object->set_prototype(&prototype.as_object());
if (exception())
return {};
}
}
call_frame.this_value = new_object;
// If we are a Derived constructor, |this| has not been constructed before super is called.
Value this_value = function.constructor_kind() == Function::ConstructorKind::Base ? new_object : Value {};
call_frame.this_value = this_value;
auto result = function.construct(*this);
this_value = current_environment()->get_this_binding();
pop_call_frame();
// If we are constructing an instance of a derived class,
// set the prototype on objects created by constructors that return an object (i.e. NativeFunction subclasses).
if (function.constructor_kind() == Function::ConstructorKind::Base && new_target.constructor_kind() == Function::ConstructorKind::Derived && result.is_object()) {
current_environment()->replace_this_binding(result);
auto prototype = new_target.get("prototype");
if (exception())
return {};
if (prototype.is_object()) {
result.as_object().set_prototype(&prototype.as_object());
if (exception())
return {};
}
return result;
}
if (exception())
return {};
if (result.is_object())
return result;
return new_object;
return this_value;
}
Value Interpreter::throw_exception(Exception* exception)
@ -301,4 +338,24 @@ String Interpreter::join_arguments() const
return joined_arguments.build();
}
Value Interpreter::resolve_this_binding() const
{
return get_this_environment()->get_this_binding();
}
const LexicalEnvironment* Interpreter::get_this_environment() const
{
// We will always return because the Global environment will always be reached, which has a |this| binding.
for (const LexicalEnvironment* environment = current_environment(); environment; environment = environment->parent()) {
if (environment->has_this_binding())
return environment;
}
ASSERT_NOT_REACHED();
}
Value Interpreter::get_new_target() const
{
return get_this_environment()->new_target();
}
}