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/*
* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/ObjectEnvironment.h>
namespace JS {
ObjectEnvironment::ObjectEnvironment(Object& binding_object, IsWithEnvironment is_with_environment, Environment* outer_environment)
: Environment(outer_environment)
, m_binding_object(binding_object)
, m_with_environment(is_with_environment == IsWithEnvironment::Yes)
{
}
void ObjectEnvironment::visit_edges(Cell::Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_binding_object);
}
// 9.1.1.2.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-object-environment-records-hasbinding-n
ThrowCompletionOr<bool> ObjectEnvironment::has_binding(DeprecatedFlyString const& name, Optional<size_t>*) const
{
auto& vm = this->vm();
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Let foundBinding be ? HasProperty(bindingObject, N).
bool found_binding = TRY(m_binding_object->has_property(name));
// 3. If foundBinding is false, return false.
if (!found_binding)
return false;
// 4. If envRec.[[IsWithEnvironment]] is false, return true.
if (!m_with_environment)
return true;
// 5. Let unscopables be ? Get(bindingObject, @@unscopables).
auto unscopables = TRY(m_binding_object->get(*vm.well_known_symbol_unscopables()));
// 6. If Type(unscopables) is Object, then
if (unscopables.is_object()) {
// a. Let blocked be ToBoolean(? Get(unscopables, N)).
auto blocked = TRY(unscopables.as_object().get(name)).to_boolean();
// b. If blocked is true, return false.
if (blocked)
return false;
}
// 7. Return true.
return true;
}
// 9.1.1.2.2 CreateMutableBinding ( N, D ), https://tc39.es/ecma262/#sec-object-environment-records-createmutablebinding-n-d
ThrowCompletionOr<void> ObjectEnvironment::create_mutable_binding(VM&, DeprecatedFlyString const& name, bool can_be_deleted)
{
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Perform ? DefinePropertyOrThrow(bindingObject, N, PropertyDescriptor { [[Value]]: undefined, [[Writable]]: true, [[Enumerable]]: true, [[Configurable]]: D }).
TRY(m_binding_object->define_property_or_throw(name, { .value = js_undefined(), .writable = true, .enumerable = true, .configurable = can_be_deleted }));
// 3. Return unused.
return {};
}
// 9.1.1.2.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-object-environment-records-createimmutablebinding-n-s
ThrowCompletionOr<void> ObjectEnvironment::create_immutable_binding(VM&, DeprecatedFlyString const&, bool)
{
// "The CreateImmutableBinding concrete method of an object Environment Record is never used within this specification."
VERIFY_NOT_REACHED();
}
// 9.1.1.2.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-object-environment-records-initializebinding-n-v
ThrowCompletionOr<void> ObjectEnvironment::initialize_binding(VM& vm, DeprecatedFlyString const& name, Value value, Environment::InitializeBindingHint hint)
{
// 1. Assert: hint is normal.
VERIFY(hint == Environment::InitializeBindingHint::Normal);
// 2. Perform ? envRec.SetMutableBinding(N, V, false).
TRY(set_mutable_binding(vm, name, value, false));
// 2. Return unused.
return {};
}
// 9.1.1.2.5 SetMutableBinding ( N, V, S ), https://tc39.es/ecma262/#sec-object-environment-records-setmutablebinding-n-v-s
ThrowCompletionOr<void> ObjectEnvironment::set_mutable_binding(VM&, DeprecatedFlyString const& name, Value value, bool strict)
{
auto& vm = this->vm();
// OPTIMIZATION: For non-with environments in non-strict mode, we don't need the separate HasProperty check since we only use that
// information to throw errors in strict mode.
// We can't do this for with environments, since it would be observable (e.g via a Proxy)
// FIXME: I think we could combine HasProperty and Set in strict mode if Set would return a bit more failure information.
if (!m_with_environment && !strict)
return m_binding_object->set(name, value, Object::ShouldThrowExceptions::No);
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Let stillExists be ? HasProperty(bindingObject, N).
auto still_exists = TRY(m_binding_object->has_property(name));
// 3. If stillExists is false and S is true, throw a ReferenceError exception.
if (!still_exists && strict)
return vm.throw_completion<ReferenceError>(ErrorType::UnknownIdentifier, name);
// 4. Perform ? Set(bindingObject, N, V, S).
auto result_or_error = m_binding_object->set(name, value, strict ? Object::ShouldThrowExceptions::Yes : Object::ShouldThrowExceptions::No);
// Note: Nothing like this in the spec, this is here to produce nicer errors instead of the generic one thrown by Object::set().
if (result_or_error.is_error() && strict) {
auto property_or_error = m_binding_object->internal_get_own_property(name);
// Return the initial error instead of masking it with the new error
if (property_or_error.is_error())
return result_or_error.release_error();
auto property = property_or_error.release_value();
if (property.has_value() && !property->writable.value_or(true)) {
return vm.throw_completion<TypeError>(ErrorType::DescWriteNonWritable, name);
}
}
if (result_or_error.is_error())
return result_or_error.release_error();
// 5. Return unused.
return {};
}
// 9.1.1.2.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-object-environment-records-getbindingvalue-n-s
ThrowCompletionOr<Value> ObjectEnvironment::get_binding_value(VM&, DeprecatedFlyString const& name, bool strict)
{
auto& vm = this->vm();
// OPTIMIZATION: For non-with environments in non-strict mode, we don't need the separate HasProperty check
// since Get will return undefined for missing properties anyway. So we take advantage of this
// to avoid doing both HasProperty and Get.
// We can't do this for with environments, since it would be observable (e.g via a Proxy)
// FIXME: We could combine HasProperty and Get in non-strict mode if Get would return a bit more failure information.
if (!m_with_environment && !strict)
return m_binding_object->get(name);
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Let value be ? HasProperty(bindingObject, N).
auto value = TRY(m_binding_object->has_property(name));
// 3. If value is false, then
if (!value) {
// a. If S is false, return undefined; otherwise throw a ReferenceError exception.
if (!strict)
return js_undefined();
return vm.throw_completion<ReferenceError>(ErrorType::UnknownIdentifier, name);
}
// 4. Return ? Get(bindingObject, N).
return m_binding_object->get(name);
}
// 9.1.1.2.7 DeleteBinding ( N ), https://tc39.es/ecma262/#sec-object-environment-records-deletebinding-n
ThrowCompletionOr<bool> ObjectEnvironment::delete_binding(VM&, DeprecatedFlyString const& name)
{
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Return ? bindingObject.[[Delete]](N).
return m_binding_object->internal_delete(name);
}
}
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