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LibJS: Start implementing spec-compliant variable bindings

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This patch adds the concept of variable bindings to the various
environment record classes. The bindings are not yet hooked up to
anything, this is just fleshing out all the operations.

Most of this is following the spec exactly, but in a few cases we are
missing the requisite abstract operations to do the exact right thing.
I've added FIXME's in those cases where I noticed it.
This commit is contained in:
Andreas Kling 2021-06-23 12:26:37 +02:00
parent 2822da8c8f
commit 9d49a5478a
8 changed files with 360 additions and 4 deletions
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144
Userland/Libraries/LibJS/Runtime/GlobalEnvironmentRecord.cpp
View file

@ -55,4 +55,148 @@ Value GlobalEnvironmentRecord::global_this_value() const
return &m_global_object;
}
// 9.1.1.4.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-global-environment-records-hasbinding-n
bool GlobalEnvironmentRecord::has_binding(FlyString const& name) const
{
if (m_declarative_record->has_binding(name))
return true;
return m_object_record->has_binding(name);
}
void GlobalEnvironmentRecord::create_mutable_binding(GlobalObject& global_object, FlyString const& name, bool can_be_deleted)
{
if (m_declarative_record->has_binding(name)) {
global_object.vm().throw_exception<TypeError>(global_object, ErrorType::FixmeAddAnErrorString);
return;
}
m_declarative_record->create_mutable_binding(global_object, name, can_be_deleted);
}
void GlobalEnvironmentRecord::create_immutable_binding(GlobalObject& global_object, FlyString const& name, bool strict)
{
if (m_declarative_record->has_binding(name)) {
global_object.vm().throw_exception<TypeError>(global_object, ErrorType::FixmeAddAnErrorString);
return;
}
m_declarative_record->create_immutable_binding(global_object, name, strict);
}
void GlobalEnvironmentRecord::initialize_binding(GlobalObject& global_object, FlyString const& name, Value value)
{
if (m_declarative_record->has_binding(name)) {
m_declarative_record->initialize_binding(global_object, name, value);
return;
}
m_object_record->initialize_binding(global_object, name, value);
}
void GlobalEnvironmentRecord::set_mutable_binding(GlobalObject& global_object, FlyString const& name, Value value, bool strict)
{
if (m_declarative_record->has_binding(name)) {
m_declarative_record->set_mutable_binding(global_object, name, value, strict);
return;
}
m_object_record->set_mutable_binding(global_object, name, value, strict);
}
Value GlobalEnvironmentRecord::get_binding_value(GlobalObject& global_object, FlyString const& name, bool strict)
{
if (m_declarative_record->has_binding(name))
return m_declarative_record->get_binding_value(global_object, name, strict);
return m_object_record->get_binding_value(global_object, name, strict);
}
bool GlobalEnvironmentRecord::delete_binding(GlobalObject& global_object, FlyString const& name)
{
if (m_declarative_record->has_binding(name))
return m_declarative_record->delete_binding(global_object, name);
bool existing_prop = m_object_record->object().has_own_property(name);
if (existing_prop) {
bool status = m_object_record->delete_binding(global_object, name);
if (status) {
m_var_names.remove_all_matching([&](auto& entry) { return entry == name; });
}
return status;
}
return true;
}
bool GlobalEnvironmentRecord::has_var_declaration(FlyString const& name) const
{
return m_var_names.contains_slow(name);
}
bool GlobalEnvironmentRecord::has_lexical_declaration(FlyString const& name) const
{
return m_declarative_record->has_binding(name);
}
bool GlobalEnvironmentRecord::has_restricted_global_property(FlyString const& name) const
{
auto existing_prop = m_global_object.get_own_property_descriptor(name);
if (!existing_prop.has_value() || existing_prop.value().value.is_undefined())
return false;
if (existing_prop.value().attributes.is_configurable())
return false;
return true;
}
bool GlobalEnvironmentRecord::can_declare_global_var(FlyString const& name) const
{
bool has_property = m_object_record->object().has_own_property(name);
if (has_property)
return true;
return m_object_record->object().is_extensible();
}
bool GlobalEnvironmentRecord::can_declare_global_function(FlyString const& name) const
{
auto existing_prop = m_object_record->object().get_own_property_descriptor(name);
if (!existing_prop.has_value() || existing_prop.value().value.is_undefined())
return m_object_record->object().is_extensible();
if (existing_prop.value().attributes.is_configurable())
return true;
if (existing_prop.value().is_data_descriptor() && existing_prop.value().attributes.is_writable() && existing_prop.value().attributes.is_enumerable())
return true;
return false;
}
void GlobalEnvironmentRecord::create_global_var_binding(FlyString const& name, bool can_be_deleted)
{
bool has_property = m_object_record->object().has_own_property(name);
bool extensible = m_object_record->object().is_extensible();
if (!has_property && extensible) {
m_object_record->create_mutable_binding(static_cast<GlobalObject&>(m_object_record->object()), name, can_be_deleted);
m_object_record->initialize_binding(m_object_record->global_object(), name, js_undefined());
}
if (!m_var_names.contains_slow(name))
m_var_names.append(name);
}
void GlobalEnvironmentRecord::create_global_function_binding(FlyString const& name, Value value, bool can_be_deleted)
{
auto existing_prop = m_object_record->object().get_own_property_descriptor(name);
PropertyDescriptor desc;
if (!existing_prop.has_value() || existing_prop.value().value.is_undefined() || existing_prop.value().attributes.is_configurable()) {
desc.value = value;
desc.attributes.set_has_writable();
desc.attributes.set_writable();
desc.attributes.set_has_enumerable();
desc.attributes.set_enumerable();
desc.attributes.set_has_configurable();
if (can_be_deleted)
desc.attributes.set_configurable();
} else {
desc.value = value;
}
// FIXME: This should be DefinePropertyOrThrow, followed by Set
m_object_record->object().define_property(name, value, desc.attributes);
if (vm().exception())
return;
if (!m_var_names.contains_slow(name))
m_var_names.append(name);
}
}