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LibJS: Bring function environment records closer to the spec

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This patch adds FunctionEnvironmentRecord as a subclass of the existing
DeclarativeEnvironmentRecord. Things that are specific to function
environment records move into there, simplifying the base.

Most of the abstract operations related to function environment records
are rewritten to match the spec exactly. I also had to implement
GetThisEnvironment() and GetSuperConstructor() to keep tests working
after the changes, so that's nice as well. :^)
This commit is contained in:
Andreas Kling 2021-06-22 13:30:48 +02:00
parent 6ed6434bab
commit aabd82d508
28 changed files with 228 additions and 159 deletions
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50
Userland/Libraries/LibJS/Runtime/DeclarativeEnvironmentRecord.cpp
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@ -49,9 +49,6 @@ DeclarativeEnvironmentRecord::~DeclarativeEnvironmentRecord()
void DeclarativeEnvironmentRecord::visit_edges(Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_this_value);
visitor.visit(m_new_target);
visitor.visit(m_current_function);
for (auto& it : m_variables)
visitor.visit(it.value.value);
}
@ -71,51 +68,4 @@ bool DeclarativeEnvironmentRecord::delete_from_environment_record(FlyString cons
return m_variables.remove(name);
}
Value DeclarativeEnvironmentRecord::get_super_base()
{
if (m_environment_record_type != EnvironmentRecordType::Function)
return {};
VERIFY(m_current_function);
auto home_object = m_current_function->home_object();
if (!home_object.is_object())
return {};
return home_object.as_object().prototype();
}
bool DeclarativeEnvironmentRecord::has_this_binding() const
{
// More like "is_capable_of_having_a_this_binding".
switch (m_environment_record_type) {
case EnvironmentRecordType::Declarative:
case EnvironmentRecordType::Object:
return false;
case EnvironmentRecordType::Function:
return this_binding_status() != ThisBindingStatus::Lexical;
case EnvironmentRecordType::Module:
return true;
}
VERIFY_NOT_REACHED();
}
Value DeclarativeEnvironmentRecord::get_this_binding(GlobalObject& global_object) const
{
VERIFY(has_this_binding());
if (this_binding_status() == ThisBindingStatus::Uninitialized) {
vm().throw_exception<ReferenceError>(global_object, ErrorType::ThisHasNotBeenInitialized);
return {};
}
return m_this_value;
}
void DeclarativeEnvironmentRecord::bind_this_value(GlobalObject& global_object, Value this_value)
{
VERIFY(has_this_binding());
if (m_this_binding_status == ThisBindingStatus::Initialized) {
vm().throw_exception<ReferenceError>(global_object, ErrorType::ThisIsAlreadyInitialized);
return;
}
m_this_value = this_value;
m_this_binding_status = ThisBindingStatus::Initialized;
}
}