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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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32
Userland/Libraries/LibJS/Runtime/VM.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2020-2021, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
@ -9,9 +9,11 @@
#include <AK/ScopeGuard.h>
#include <AK/StringBuilder.h>
#include <LibJS/Interpreter.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/FinalizationRegistry.h>
#include <LibJS/Runtime/FunctionEnvironmentRecord.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/IteratorOperations.h>
#include <LibJS/Runtime/NativeFunction.h>
@ -460,8 +462,8 @@ Value VM::construct(Function& function, Function& new_target, Optional<MarkedVal
// 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()) {
if (environment) {
VERIFY(is<DeclarativeEnvironmentRecord>(current_environment_record()));
static_cast<DeclarativeEnvironmentRecord*>(current_environment_record())->replace_this_binding(result);
VERIFY(is<FunctionEnvironmentRecord>(current_environment_record()));
static_cast<FunctionEnvironmentRecord*>(current_environment_record())->replace_this_binding(result);
}
auto prototype = new_target.get(names.prototype);
if (exception())
@ -500,25 +502,11 @@ String VM::join_arguments(size_t start_index) const
return joined_arguments.build();
}
Value VM::resolve_this_binding(GlobalObject& global_object) const
Value VM::get_new_target()
{
return find_this_scope()->get_this_binding(global_object);
}
const EnvironmentRecord* VM::find_this_scope() const
{
// We will always return because the Global environment will always be reached, which has a |this| binding.
for (auto* environment_record = current_environment_record(); environment_record; environment_record = environment_record->outer_environment()) {
if (environment_record->has_this_binding())
return environment_record;
}
VERIFY_NOT_REACHED();
}
Value VM::get_new_target() const
{
VERIFY(is<DeclarativeEnvironmentRecord>(find_this_scope()));
return static_cast<const DeclarativeEnvironmentRecord*>(find_this_scope())->new_target();
auto& env = get_this_environment(*this);
VERIFY(is<FunctionEnvironmentRecord>(env));
return static_cast<FunctionEnvironmentRecord&>(env).new_target();
}
Value VM::call_internal(Function& function, Value this_value, Optional<MarkedValueList> arguments)
@ -540,7 +528,7 @@ Value VM::call_internal(Function& function, Value this_value, Optional<MarkedVal
call_frame.environment_record = environment;
if (environment) {
VERIFY(environment->this_binding_status() == DeclarativeEnvironmentRecord::ThisBindingStatus::Uninitialized);
VERIFY(environment->this_binding_status() == FunctionEnvironmentRecord::ThisBindingStatus::Uninitialized);
environment->bind_this_value(function.global_object(), call_frame.this_value);
}