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ladybird/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
davidot 541637e15a LibJS: Add using declaration support, RAII like operation in js 
In this patch only top level and not the more complicated for loop using
statements are supported. Also, as noted in the latest meeting of tc39
async parts of the spec are not stage 3 thus not included.
2023-01-23 09:56:50 +00:00

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/*
* Copyright (c) 2020, Stephan Unverwerth <s.unverwerth@serenityos.org>
* Copyright (c) 2020-2022, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Debug.h>
#include <AK/Function.h>
#include <LibJS/AST.h>
#include <LibJS/Bytecode/BasicBlock.h>
#include <LibJS/Bytecode/Generator.h>
#include <LibJS/Bytecode/Interpreter.h>
#include <LibJS/Interpreter.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/AsyncFunctionDriverWrapper.h>
#include <LibJS/Runtime/ECMAScriptFunctionObject.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/ExecutionContext.h>
#include <LibJS/Runtime/FunctionEnvironment.h>
#include <LibJS/Runtime/GeneratorObject.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/NativeFunction.h>
#include <LibJS/Runtime/PromiseCapability.h>
#include <LibJS/Runtime/PromiseConstructor.h>
#include <LibJS/Runtime/Value.h>
namespace JS {
NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
{
Object* prototype = nullptr;
switch (kind) {
case FunctionKind::Normal:
prototype = realm.intrinsics().function_prototype();
break;
case FunctionKind::Generator:
prototype = realm.intrinsics().generator_function_prototype();
break;
case FunctionKind::Async:
prototype = realm.intrinsics().async_function_prototype();
break;
case FunctionKind::AsyncGenerator:
prototype = realm.intrinsics().async_generator_function_prototype();
break;
}
return realm.heap().allocate<ECMAScriptFunctionObject>(realm, move(name), move(source_text), ecmascript_code, move(parameters), m_function_length, parent_environment, private_environment, *prototype, kind, is_strict, might_need_arguments_object, contains_direct_call_to_eval, is_arrow_function, move(class_field_initializer_name));
}
NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, Object& prototype, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
{
return realm.heap().allocate<ECMAScriptFunctionObject>(realm, move(name), move(source_text), ecmascript_code, move(parameters), m_function_length, parent_environment, private_environment, prototype, kind, is_strict, might_need_arguments_object, contains_direct_call_to_eval, is_arrow_function, move(class_field_initializer_name));
}
ECMAScriptFunctionObject::ECMAScriptFunctionObject(DeprecatedFlyString name, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> formal_parameters, i32 function_length, Environment* parent_environment, PrivateEnvironment* private_environment, Object& prototype, FunctionKind kind, bool strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
: FunctionObject(prototype)
, m_name(move(name))
, m_function_length(function_length)
, m_environment(parent_environment)
, m_private_environment(private_environment)
, m_formal_parameters(move(formal_parameters))
, m_ecmascript_code(ecmascript_code)
, m_realm(&prototype.shape().realm())
, m_source_text(move(source_text))
, m_class_field_initializer_name(move(class_field_initializer_name))
, m_strict(strict)
, m_might_need_arguments_object(might_need_arguments_object)
, m_contains_direct_call_to_eval(contains_direct_call_to_eval)
, m_is_arrow_function(is_arrow_function)
, m_kind(kind)
{
// NOTE: This logic is from OrdinaryFunctionCreate, https://tc39.es/ecma262/#sec-ordinaryfunctioncreate
// 9. If thisMode is lexical-this, set F.[[ThisMode]] to lexical.
if (m_is_arrow_function)
m_this_mode = ThisMode::Lexical;
// 10. Else if Strict is true, set F.[[ThisMode]] to strict.
else if (m_strict)
m_this_mode = ThisMode::Strict;
else
// 11. Else, set F.[[ThisMode]] to global.
m_this_mode = ThisMode::Global;
// 15. Set F.[[ScriptOrModule]] to GetActiveScriptOrModule().
m_script_or_module = vm().get_active_script_or_module();
// 15.1.3 Static Semantics: IsSimpleParameterList, https://tc39.es/ecma262/#sec-static-semantics-issimpleparameterlist
m_has_simple_parameter_list = all_of(m_formal_parameters, [&](auto& parameter) {
if (parameter.is_rest)
return false;
if (parameter.default_value)
return false;
if (!parameter.binding.template has<DeprecatedFlyString>())
return false;
return true;
});
}
void ECMAScriptFunctionObject::initialize(Realm& realm)
{
auto& vm = this->vm();
Base::initialize(realm);
// Note: The ordering of these properties must be: length, name, prototype which is the order
// they are defined in the spec: https://tc39.es/ecma262/#sec-function-instances .
// This is observable through something like: https://tc39.es/ecma262/#sec-ordinaryownpropertykeys
// which must give the properties in chronological order which in this case is the order they
// are defined in the spec.
MUST(define_property_or_throw(vm.names.length, { .value = Value(m_function_length), .writable = false, .enumerable = false, .configurable = true }));
MUST(define_property_or_throw(vm.names.name, { .value = PrimitiveString::create(vm, m_name.is_null() ? "" : m_name), .writable = false, .enumerable = false, .configurable = true }));
if (!m_is_arrow_function) {
Object* prototype = nullptr;
switch (m_kind) {
case FunctionKind::Normal:
prototype = vm.heap().allocate<Object>(realm, *realm.intrinsics().new_ordinary_function_prototype_object_shape());
MUST(prototype->define_property_or_throw(vm.names.constructor, { .value = this, .writable = true, .enumerable = false, .configurable = true }));
break;
case FunctionKind::Generator:
// prototype is "g1.prototype" in figure-2 (https://tc39.es/ecma262/img/figure-2.png)
prototype = Object::create(realm, realm.intrinsics().generator_function_prototype_prototype());
break;
case FunctionKind::Async:
break;
case FunctionKind::AsyncGenerator:
prototype = Object::create(realm, realm.intrinsics().async_generator_function_prototype_prototype());
break;
}
// 27.7.4 AsyncFunction Instances, https://tc39.es/ecma262/#sec-async-function-instances
// AsyncFunction instances do not have a prototype property as they are not constructible.
if (m_kind != FunctionKind::Async)
define_direct_property(vm.names.prototype, prototype, Attribute::Writable);
}
}
// 10.2.1 [[Call]] ( thisArgument, argumentsList ), https://tc39.es/ecma262/#sec-ecmascript-function-objects-call-thisargument-argumentslist
ThrowCompletionOr<Value> ECMAScriptFunctionObject::internal_call(Value this_argument, MarkedVector<Value> arguments_list)
{
auto& vm = this->vm();
// 1. Let callerContext be the running execution context.
// NOTE: No-op, kept by the VM in its execution context stack.
ExecutionContext callee_context(heap());
// Non-standard
callee_context.arguments.extend(move(arguments_list));
if (auto* interpreter = vm.interpreter_if_exists())
callee_context.current_node = interpreter->current_node();
// 2. Let calleeContext be PrepareForOrdinaryCall(F, undefined).
// NOTE: We throw if the end of the native stack is reached, so unlike in the spec this _does_ need an exception check.
TRY(prepare_for_ordinary_call(callee_context, nullptr));
// 3. Assert: calleeContext is now the running execution context.
VERIFY(&vm.running_execution_context() == &callee_context);
// 4. If F.[[IsClassConstructor]] is true, then
if (m_is_class_constructor) {
// a. Let error be a newly created TypeError object.
// b. NOTE: error is created in calleeContext with F's associated Realm Record.
auto throw_completion = vm.throw_completion<TypeError>(ErrorType::ClassConstructorWithoutNew, m_name);
// c. Remove calleeContext from the execution context stack and restore callerContext as the running execution context.
vm.pop_execution_context();
// d. Return ThrowCompletion(error).
return throw_completion;
}
// 5. Perform OrdinaryCallBindThis(F, calleeContext, thisArgument).
ordinary_call_bind_this(callee_context, this_argument);
// 6. Let result be Completion(OrdinaryCallEvaluateBody(F, argumentsList)).
auto result = ordinary_call_evaluate_body();
// 7. Remove calleeContext from the execution context stack and restore callerContext as the running execution context.
vm.pop_execution_context();
// 8. If result.[[Type]] is return, return result.[[Value]].
if (result.type() == Completion::Type::Return)
return result.value();
// 9. ReturnIfAbrupt(result).
if (result.is_abrupt()) {
VERIFY(result.is_error());
return result;
}
// 10. Return undefined.
return js_undefined();
}
// 10.2.2 [[Construct]] ( argumentsList, newTarget ), https://tc39.es/ecma262/#sec-ecmascript-function-objects-construct-argumentslist-newtarget
ThrowCompletionOr<NonnullGCPtr<Object>> ECMAScriptFunctionObject::internal_construct(MarkedVector<Value> arguments_list, FunctionObject& new_target)
{
auto& vm = this->vm();
// 1. Let callerContext be the running execution context.
// NOTE: No-op, kept by the VM in its execution context stack.
// 2. Let kind be F.[[ConstructorKind]].
auto kind = m_constructor_kind;
GCPtr<Object> this_argument;
// 3. If kind is base, then
if (kind == ConstructorKind::Base) {
// a. Let thisArgument be ? OrdinaryCreateFromConstructor(newTarget, "%Object.prototype%").
this_argument = TRY(ordinary_create_from_constructor<Object>(vm, new_target, &Intrinsics::object_prototype, ConstructWithPrototypeTag::Tag));
}
ExecutionContext callee_context(heap());
// Non-standard
callee_context.arguments.extend(move(arguments_list));
if (auto* interpreter = vm.interpreter_if_exists())
callee_context.current_node = interpreter->current_node();
// 4. Let calleeContext be PrepareForOrdinaryCall(F, newTarget).
// NOTE: We throw if the end of the native stack is reached, so unlike in the spec this _does_ need an exception check.
TRY(prepare_for_ordinary_call(callee_context, &new_target));
// 5. Assert: calleeContext is now the running execution context.
VERIFY(&vm.running_execution_context() == &callee_context);
// 6. If kind is base, then
if (kind == ConstructorKind::Base) {
// a. Perform OrdinaryCallBindThis(F, calleeContext, thisArgument).
ordinary_call_bind_this(callee_context, this_argument);
// b. Let initializeResult be Completion(InitializeInstanceElements(thisArgument, F)).
auto initialize_result = this_argument->initialize_instance_elements(*this);
// c. If initializeResult is an abrupt completion, then
if (initialize_result.is_throw_completion()) {
// i. Remove calleeContext from the execution context stack and restore callerContext as the running execution context.
vm.pop_execution_context();
// ii. Return ? initializeResult.
return initialize_result.throw_completion();
}
}
// 7. Let constructorEnv be the LexicalEnvironment of calleeContext.
auto* constructor_env = callee_context.lexical_environment;
// 8. Let result be Completion(OrdinaryCallEvaluateBody(F, argumentsList)).
auto result = ordinary_call_evaluate_body();
// 9. Remove calleeContext from the execution context stack and restore callerContext as the running execution context.
vm.pop_execution_context();
// 10. If result.[[Type]] is return, then
if (result.type() == Completion::Type::Return) {
// FIXME: This is leftover from untangling the call/construct mess - doesn't belong here in any way, but removing it breaks derived classes.
// Likely fixed by making ClassDefinitionEvaluation fully spec compliant.
if (kind == ConstructorKind::Derived && result.value()->is_object()) {
auto prototype = TRY(new_target.get(vm.names.prototype));
if (prototype.is_object())
TRY(result.value()->as_object().internal_set_prototype_of(&prototype.as_object()));
}
// EOF (End of FIXME)
// a. If Type(result.[[Value]]) is Object, return result.[[Value]].
if (result.value()->is_object())
return result.value()->as_object();
// b. If kind is base, return thisArgument.
if (kind == ConstructorKind::Base)
return *this_argument;
// c. If result.[[Value]] is not undefined, throw a TypeError exception.
if (!result.value()->is_undefined())
return vm.throw_completion<TypeError>(ErrorType::DerivedConstructorReturningInvalidValue);
}
// 11. Else, ReturnIfAbrupt(result).
else if (result.is_abrupt()) {
VERIFY(result.is_error());
return result;
}
// 12. Let thisBinding be ? constructorEnv.GetThisBinding().
auto this_binding = TRY(constructor_env->get_this_binding(vm));
// 13. Assert: Type(thisBinding) is Object.
VERIFY(this_binding.is_object());
// 14. Return thisBinding.
return this_binding.as_object();
}
void ECMAScriptFunctionObject::visit_edges(Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_environment);
visitor.visit(m_private_environment);
visitor.visit(m_realm);
visitor.visit(m_home_object);
for (auto& field : m_fields) {
if (auto* property_key_ptr = field.name.get_pointer<PropertyKey>(); property_key_ptr && property_key_ptr->is_symbol())
visitor.visit(property_key_ptr->as_symbol());
}
m_script_or_module.visit(
[](Empty) {},
[&](auto& script_or_module) {
visitor.visit(script_or_module.ptr());
});
}
// 10.2.7 MakeMethod ( F, homeObject ), https://tc39.es/ecma262/#sec-makemethod
void ECMAScriptFunctionObject::make_method(Object& home_object)
{
// 1. Set F.[[HomeObject]] to homeObject.
m_home_object = &home_object;
// 2. Return unused.
}
// 10.2.11 FunctionDeclarationInstantiation ( func, argumentsList ), https://tc39.es/ecma262/#sec-functiondeclarationinstantiation
ThrowCompletionOr<void> ECMAScriptFunctionObject::function_declaration_instantiation(Interpreter* interpreter)
{
auto& vm = this->vm();
auto& realm = *vm.current_realm();
auto& callee_context = vm.running_execution_context();
// Needed to extract declarations and functions
ScopeNode const* scope_body = nullptr;
if (is<ScopeNode>(*m_ecmascript_code))
scope_body = static_cast<ScopeNode const*>(m_ecmascript_code.ptr());
bool has_parameter_expressions = false;
// FIXME: Maybe compute has duplicates at parse time? (We need to anyway since it's an error in some cases)
bool has_duplicates = false;
HashTable<DeprecatedFlyString> parameter_names;
for (auto& parameter : m_formal_parameters) {
if (parameter.default_value)
has_parameter_expressions = true;
parameter.binding.visit(
[&](DeprecatedFlyString const& name) {
if (parameter_names.set(name) != AK::HashSetResult::InsertedNewEntry)
has_duplicates = true;
},
[&](NonnullRefPtr<BindingPattern> const& pattern) {
if (pattern->contains_expression())
has_parameter_expressions = true;
pattern->for_each_bound_name([&](auto& name) {
if (parameter_names.set(name) != AK::HashSetResult::InsertedNewEntry)
has_duplicates = true;
});
});
}
auto arguments_object_needed = m_might_need_arguments_object;
if (this_mode() == ThisMode::Lexical)
arguments_object_needed = false;
if (parameter_names.contains(vm.names.arguments.as_string()))
arguments_object_needed = false;
HashTable<DeprecatedFlyString> function_names;
Vector<FunctionDeclaration const&> functions_to_initialize;
if (scope_body) {
scope_body->for_each_var_function_declaration_in_reverse_order([&](FunctionDeclaration const& function) {
if (function_names.set(function.name()) == AK::HashSetResult::InsertedNewEntry)
functions_to_initialize.append(function);
});
auto const& arguments_name = vm.names.arguments.as_string();
if (!has_parameter_expressions && function_names.contains(arguments_name))
arguments_object_needed = false;
if (!has_parameter_expressions && arguments_object_needed) {
scope_body->for_each_lexically_declared_name([&](auto const& name) {
if (name == arguments_name)
arguments_object_needed = false;
});
}
} else {
arguments_object_needed = false;
}
GCPtr<Environment> environment;
if (is_strict_mode() || !has_parameter_expressions) {
environment = callee_context.lexical_environment;
} else {
environment = new_declarative_environment(*callee_context.lexical_environment);
VERIFY(callee_context.variable_environment == callee_context.lexical_environment);
callee_context.lexical_environment = environment;
}
for (auto const& parameter_name : parameter_names) {
if (MUST(environment->has_binding(parameter_name)))
continue;
MUST(environment->create_mutable_binding(vm, parameter_name, false));
if (has_duplicates)
MUST(environment->initialize_binding(vm, parameter_name, js_undefined(), Environment::InitializeBindingHint::Normal));
}
if (arguments_object_needed) {
Object* arguments_object;
if (is_strict_mode() || !has_simple_parameter_list())
arguments_object = create_unmapped_arguments_object(vm, vm.running_execution_context().arguments);
else
arguments_object = create_mapped_arguments_object(vm, *this, formal_parameters(), vm.running_execution_context().arguments, *environment);
if (is_strict_mode())
MUST(environment->create_immutable_binding(vm, vm.names.arguments.as_string(), false));
else
MUST(environment->create_mutable_binding(vm, vm.names.arguments.as_string(), false));
MUST(environment->initialize_binding(vm, vm.names.arguments.as_string(), arguments_object, Environment::InitializeBindingHint::Normal));
parameter_names.set(vm.names.arguments.as_string());
}
// We now treat parameterBindings as parameterNames.
// The spec makes an iterator here to do IteratorBindingInitialization but we just do it manually
auto& execution_context_arguments = vm.running_execution_context().arguments;
size_t default_parameter_index = 0;
for (size_t i = 0; i < m_formal_parameters.size(); ++i) {
auto& parameter = m_formal_parameters[i];
if (parameter.default_value)
++default_parameter_index;
TRY(parameter.binding.visit(
[&](auto const& param) -> ThrowCompletionOr<void> {
Value argument_value;
if (parameter.is_rest) {
auto array = MUST(Array::create(realm, 0));
for (size_t rest_index = i; rest_index < execution_context_arguments.size(); ++rest_index)
array->indexed_properties().append(execution_context_arguments[rest_index]);
argument_value = array;
} else if (i < execution_context_arguments.size() && !execution_context_arguments[i].is_undefined()) {
argument_value = execution_context_arguments[i];
} else if (parameter.default_value) {
if (auto* bytecode_interpreter = Bytecode::Interpreter::current()) {
auto value_and_frame = bytecode_interpreter->run_and_return_frame(*m_default_parameter_bytecode_executables[default_parameter_index - 1], nullptr);
if (value_and_frame.value.is_error())
return value_and_frame.value.release_error();
// Resulting value is in the accumulator.
argument_value = value_and_frame.frame->registers.at(0);
} else if (interpreter) {
argument_value = TRY(parameter.default_value->execute(*interpreter)).release_value();
}
} else {
argument_value = js_undefined();
}
Environment* used_environment = has_duplicates ? nullptr : environment;
if constexpr (IsSame<DeprecatedFlyString const&, decltype(param)>) {
Reference reference = TRY(vm.resolve_binding(param, used_environment));
// Here the difference from hasDuplicates is important
if (has_duplicates)
return reference.put_value(vm, argument_value);
else
return reference.initialize_referenced_binding(vm, argument_value);
} else if (IsSame<NonnullRefPtr<BindingPattern> const&, decltype(param)>) {
// Here the difference from hasDuplicates is important
return vm.binding_initialization(param, argument_value, used_environment);
}
}));
}
GCPtr<Environment> var_environment;
HashTable<DeprecatedFlyString> instantiated_var_names;
if (scope_body)
instantiated_var_names.ensure_capacity(scope_body->var_declaration_count());
if (!has_parameter_expressions) {
if (scope_body) {
scope_body->for_each_var_declared_name([&](auto const& name) {
if (!parameter_names.contains(name) && instantiated_var_names.set(name) == AK::HashSetResult::InsertedNewEntry) {
MUST(environment->create_mutable_binding(vm, name, false));
MUST(environment->initialize_binding(vm, name, js_undefined(), Environment::InitializeBindingHint::Normal));
}
});
}
var_environment = environment;
} else {
var_environment = new_declarative_environment(*environment);
callee_context.variable_environment = var_environment;
if (scope_body) {
scope_body->for_each_var_declared_name([&](auto const& name) {
if (instantiated_var_names.set(name) != AK::HashSetResult::InsertedNewEntry)
return;
MUST(var_environment->create_mutable_binding(vm, name, false));
Value initial_value;
if (!parameter_names.contains(name) || function_names.contains(name))
initial_value = js_undefined();
else
initial_value = MUST(environment->get_binding_value(vm, name, false));
MUST(var_environment->initialize_binding(vm, name, initial_value, Environment::InitializeBindingHint::Normal));
});
}
}
// B.3.2.1 Changes to FunctionDeclarationInstantiation, https://tc39.es/ecma262/#sec-web-compat-functiondeclarationinstantiation
if (!m_strict && scope_body) {
scope_body->for_each_function_hoistable_with_annexB_extension([&](FunctionDeclaration& function_declaration) {
auto& function_name = function_declaration.name();
if (parameter_names.contains(function_name))
return;
// The spec says 'initializedBindings' here but that does not exist and it then adds it to 'instantiatedVarNames' so it probably means 'instantiatedVarNames'.
if (!instantiated_var_names.contains(function_name) && function_name != vm.names.arguments.as_string()) {
MUST(var_environment->create_mutable_binding(vm, function_name, false));
MUST(var_environment->initialize_binding(vm, function_name, js_undefined(), Environment::InitializeBindingHint::Normal));
instantiated_var_names.set(function_name);
}
function_declaration.set_should_do_additional_annexB_steps();
});
}
GCPtr<Environment> lex_environment;
// 30. If strict is false, then
if (!is_strict_mode()) {
// Optimization: We avoid creating empty top-level declarative environments in non-strict mode, if both of these conditions are true:
// 1. there is no direct call to eval() within this function
// 2. there are no lexical declarations that would go into the environment
bool can_elide_declarative_environment = !m_contains_direct_call_to_eval && (!scope_body || !scope_body->has_lexical_declarations());
if (can_elide_declarative_environment) {
lex_environment = var_environment;
} else {
// a. Let lexEnv be NewDeclarativeEnvironment(varEnv).
// b. NOTE: Non-strict functions use a separate Environment Record for top-level lexical declarations so that a direct eval
// can determine whether any var scoped declarations introduced by the eval code conflict with pre-existing top-level
// lexically scoped declarations. This is not needed for strict functions because a strict direct eval always places
// all declarations into a new Environment Record.
lex_environment = new_declarative_environment(*var_environment);
}
} else {
// 31. Else, let lexEnv be varEnv.
lex_environment = var_environment;
}
// 32. Set the LexicalEnvironment of calleeContext to lexEnv.
callee_context.lexical_environment = lex_environment;
if (!scope_body)
return {};
if (!Bytecode::Interpreter::current()) {
scope_body->for_each_lexically_scoped_declaration([&](Declaration const& declaration) {
declaration.for_each_bound_name([&](auto const& name) {
if (declaration.is_constant_declaration())
MUST(lex_environment->create_immutable_binding(vm, name, true));
else
MUST(lex_environment->create_mutable_binding(vm, name, false));
});
});
}
auto* private_environment = callee_context.private_environment;
for (auto& declaration : functions_to_initialize) {
auto function = ECMAScriptFunctionObject::create(realm, declaration.name(), declaration.source_text(), declaration.body(), declaration.parameters(), declaration.function_length(), lex_environment, private_environment, declaration.kind(), declaration.is_strict_mode(), declaration.might_need_arguments_object(), declaration.contains_direct_call_to_eval());
MUST(var_environment->set_mutable_binding(vm, declaration.name(), function, false));
}
if (is<DeclarativeEnvironment>(*lex_environment))
static_cast<DeclarativeEnvironment*>(lex_environment.ptr())->shrink_to_fit();
if (is<DeclarativeEnvironment>(*var_environment))
static_cast<DeclarativeEnvironment*>(var_environment.ptr())->shrink_to_fit();
return {};
}
// 10.2.1.1 PrepareForOrdinaryCall ( F, newTarget ), https://tc39.es/ecma262/#sec-prepareforordinarycall
ThrowCompletionOr<void> ECMAScriptFunctionObject::prepare_for_ordinary_call(ExecutionContext& callee_context, Object* new_target)
{
auto& vm = this->vm();
// Non-standard
callee_context.is_strict_mode = m_strict;
// 1. Let callerContext be the running execution context.
// 2. Let calleeContext be a new ECMAScript code execution context.
// NOTE: In the specification, PrepareForOrdinaryCall "returns" a new callee execution context.
// To avoid heap allocations, we put our ExecutionContext objects on the C++ stack instead.
// Whoever calls us should put an ExecutionContext on their stack and pass that as the `callee_context`.
// 3. Set the Function of calleeContext to F.
callee_context.function = this;
callee_context.function_name = m_name;
// 4. Let calleeRealm be F.[[Realm]].
auto* callee_realm = m_realm;
// NOTE: This non-standard fallback is needed until we can guarantee that literally
// every function has a realm - especially in LibWeb that's sometimes not the case
// when a function is created while no JS is running, as we currently need to rely on
// that (:acid2:, I know - see set_event_handler_attribute() for an example).
// If there's no 'current realm' either, we can't continue and crash.
if (!callee_realm)
callee_realm = vm.current_realm();
VERIFY(callee_realm);
// 5. Set the Realm of calleeContext to calleeRealm.
callee_context.realm = callee_realm;
// 6. Set the ScriptOrModule of calleeContext to F.[[ScriptOrModule]].
callee_context.script_or_module = m_script_or_module;
// 7. Let localEnv be NewFunctionEnvironment(F, newTarget).
auto local_environment = new_function_environment(*this, new_target);
// 8. Set the LexicalEnvironment of calleeContext to localEnv.
callee_context.lexical_environment = local_environment;
// 9. Set the VariableEnvironment of calleeContext to localEnv.
callee_context.variable_environment = local_environment;
// 10. Set the PrivateEnvironment of calleeContext to F.[[PrivateEnvironment]].
callee_context.private_environment = m_private_environment;
// 11. If callerContext is not already suspended, suspend callerContext.
// FIXME: We don't have this concept yet.
// 12. Push calleeContext onto the execution context stack; calleeContext is now the running execution context.
TRY(vm.push_execution_context(callee_context, {}));
// 13. NOTE: Any exception objects produced after this point are associated with calleeRealm.
// 14. Return calleeContext.
// NOTE: See the comment after step 2 above about how contexts are allocated on the C++ stack.
return {};
}
// 10.2.1.2 OrdinaryCallBindThis ( F, calleeContext, thisArgument ), https://tc39.es/ecma262/#sec-ordinarycallbindthis
void ECMAScriptFunctionObject::ordinary_call_bind_this(ExecutionContext& callee_context, Value this_argument)
{
auto& vm = this->vm();
// 1. Let thisMode be F.[[ThisMode]].
auto this_mode = m_this_mode;
// If thisMode is lexical, return unused.
if (this_mode == ThisMode::Lexical)
return;
// 3. Let calleeRealm be F.[[Realm]].
auto* callee_realm = m_realm;
// NOTE: This non-standard fallback is needed until we can guarantee that literally
// every function has a realm - especially in LibWeb that's sometimes not the case
// when a function is created while no JS is running, as we currently need to rely on
// that (:acid2:, I know - see set_event_handler_attribute() for an example).
// If there's no 'current realm' either, we can't continue and crash.
if (!callee_realm)
callee_realm = vm.current_realm();
VERIFY(callee_realm);
// 4. Let localEnv be the LexicalEnvironment of calleeContext.
auto* local_env = callee_context.lexical_environment;
Value this_value;
// 5. If thisMode is strict, let thisValue be thisArgument.
if (this_mode == ThisMode::Strict) {
this_value = this_argument;
}
// 6. Else,
else {
// a. If thisArgument is undefined or null, then
if (this_argument.is_nullish()) {
// i. Let globalEnv be calleeRealm.[[GlobalEnv]].
// ii. Assert: globalEnv is a global Environment Record.
auto& global_env = callee_realm->global_environment();
// iii. Let thisValue be globalEnv.[[GlobalThisValue]].
this_value = &global_env.global_this_value();
}
// b. Else,
else {
// i. Let thisValue be ! ToObject(thisArgument).
this_value = MUST(this_argument.to_object(vm));
// ii. NOTE: ToObject produces wrapper objects using calleeRealm.
VERIFY(vm.current_realm() == callee_realm);
}
}
// 7. Assert: localEnv is a function Environment Record.
// 8. Assert: The next step never returns an abrupt completion because localEnv.[[ThisBindingStatus]] is not initialized.
// 9. Perform ! localEnv.BindThisValue(thisValue).
MUST(verify_cast<FunctionEnvironment>(local_env)->bind_this_value(vm, this_value));
// 10. Return unused.
}
// 27.7.5.1 AsyncFunctionStart ( promiseCapability, asyncFunctionBody ), https://tc39.es/ecma262/#sec-async-functions-abstract-operations-async-function-start
void ECMAScriptFunctionObject::async_function_start(PromiseCapability const& promise_capability)
{
auto& vm = this->vm();
// 1. Let runningContext be the running execution context.
auto& running_context = vm.running_execution_context();
// 2. Let asyncContext be a copy of runningContext.
auto async_context = running_context.copy();
// 3. NOTE: Copying the execution state is required for AsyncBlockStart to resume its execution. It is ill-defined to resume a currently executing context.
// 4. Perform AsyncBlockStart(promiseCapability, asyncFunctionBody, asyncContext).
async_block_start(vm, m_ecmascript_code, promise_capability, async_context);
// 5. Return unused.
}
// 27.7.5.2 AsyncBlockStart ( promiseCapability, asyncBody, asyncContext ), https://tc39.es/ecma262/#sec-asyncblockstart
void async_block_start(VM& vm, NonnullRefPtr<Statement> const& async_body, PromiseCapability const& promise_capability, ExecutionContext& async_context)
{
auto& realm = *vm.current_realm();
// 1. Assert: promiseCapability is a PromiseCapability Record.
// 2. Let runningContext be the running execution context.
auto& running_context = vm.running_execution_context();
// 3. Set the code evaluation state of asyncContext such that when evaluation is resumed for that execution context the following steps will be performed:
auto execution_steps = NativeFunction::create(realm, "", [&async_body, &promise_capability, &async_context](auto& vm) -> ThrowCompletionOr<Value> {
// a. Let result be the result of evaluating asyncBody.
auto result = async_body->execute(vm.interpreter());
// b. Assert: If we return here, the async function either threw an exception or performed an implicit or explicit return; all awaiting is done.
// c. Remove asyncContext from the execution context stack and restore the execution context that is at the top of the execution context stack as the running execution context.
vm.pop_execution_context();
// d. Let env be asyncContext's LexicalEnvironment.
auto* env = async_context.lexical_environment;
VERIFY(is<DeclarativeEnvironment>(env));
// e. Set result to DisposeResources(env, result).
result = dispose_resources(vm, static_cast<DeclarativeEnvironment*>(env), result);
// f. If result.[[Type]] is normal, then
if (result.type() == Completion::Type::Normal) {
// i. Perform ! Call(promiseCapability.[[Resolve]], undefined, « undefined »).
MUST(call(vm, *promise_capability.resolve(), js_undefined(), js_undefined()));
}
// g. Else if result.[[Type]] is return, then
else if (result.type() == Completion::Type::Return) {
// i. Perform ! Call(promiseCapability.[[Resolve]], undefined, « result.[[Value]] »).
MUST(call(vm, *promise_capability.resolve(), js_undefined(), *result.value()));
}
// h. Else,
else {
// i. Assert: result.[[Type]] is throw.
VERIFY(result.type() == Completion::Type::Throw);
// ii. Perform ! Call(promiseCapability.[[Reject]], undefined, « result.[[Value]] »).
MUST(call(vm, *promise_capability.reject(), js_undefined(), *result.value()));
}
// i. Return unused.
// NOTE: We don't support returning an empty/optional/unused value here.
return js_undefined();
});
// 4. Push asyncContext onto the execution context stack; asyncContext is now the running execution context.
auto push_result = vm.push_execution_context(async_context, {});
if (push_result.is_error())
return;
// 5. Resume the suspended evaluation of asyncContext. Let result be the value returned by the resumed computation.
auto result = call(vm, *execution_steps, async_context.this_value.is_empty() ? js_undefined() : async_context.this_value);
// 6. Assert: When we return here, asyncContext has already been removed from the execution context stack and runningContext is the currently running execution context.
VERIFY(&vm.running_execution_context() == &running_context);
// 7. Assert: result is a normal completion with a value of unused. The possible sources of this value are Await or, if the async function doesn't await anything, step 3.g above.
VERIFY(result.has_value() && result.value().is_undefined());
// 8. Return unused.
}
// 10.2.1.4 OrdinaryCallEvaluateBody ( F, argumentsList ), https://tc39.es/ecma262/#sec-ordinarycallevaluatebody
// 15.8.4 Runtime Semantics: EvaluateAsyncFunctionBody, https://tc39.es/ecma262/#sec-runtime-semantics-evaluatefunctionbody
Completion ECMAScriptFunctionObject::ordinary_call_evaluate_body()
{
auto& vm = this->vm();
auto& realm = *vm.current_realm();
if (m_kind == FunctionKind::AsyncGenerator)
return vm.throw_completion<InternalError>(ErrorType::NotImplemented, "Async Generator function execution");
auto* bytecode_interpreter = Bytecode::Interpreter::current();
// The bytecode interpreter can execute generator functions while the AST interpreter cannot.
// This simply makes it create a new bytecode interpreter when one doesn't exist when executing a generator function.
// Doing so makes it automatically switch to the bytecode interpreter to execute any future code until it exits the generator. See below.
// This allows us to keep all of the existing functionality that works in AST while adding generator support on top of it.
// However, this does cause an awkward situation with features not supported in bytecode, where features that work outside of generators with AST
// suddenly stop working inside of generators.
// This is a stop gap until bytecode mode becomes the default.
OwnPtr<Bytecode::Interpreter> temp_bc_interpreter;
if (m_kind == FunctionKind::Generator && !bytecode_interpreter) {
temp_bc_interpreter = make<Bytecode::Interpreter>(realm);
bytecode_interpreter = temp_bc_interpreter.ptr();
}
if (bytecode_interpreter) {
if (!m_bytecode_executable) {
auto compile = [&](auto& node, auto kind, auto name) -> ThrowCompletionOr<NonnullOwnPtr<Bytecode::Executable>> {
auto executable_result = Bytecode::Generator::generate(node, kind);
if (executable_result.is_error())
return vm.throw_completion<InternalError>(ErrorType::NotImplemented, executable_result.error().to_deprecated_string());
auto bytecode_executable = executable_result.release_value();
bytecode_executable->name = name;
auto& passes = Bytecode::Interpreter::optimization_pipeline();
passes.perform(*bytecode_executable);
if constexpr (JS_BYTECODE_DEBUG) {
dbgln("Optimisation passes took {}us", passes.elapsed());
dbgln("Compiled Bytecode::Block for function '{}':", m_name);
}
if (Bytecode::g_dump_bytecode)
bytecode_executable->dump();
return bytecode_executable;
};
m_bytecode_executable = TRY(compile(*m_ecmascript_code, m_kind, m_name));
size_t default_parameter_index = 0;
for (auto& parameter : m_formal_parameters) {
if (!parameter.default_value)
continue;
auto executable = TRY(compile(*parameter.default_value, FunctionKind::Normal, DeprecatedString::formatted("default parameter #{} for {}", default_parameter_index, m_name)));
m_default_parameter_bytecode_executables.append(move(executable));
}
}
TRY(function_declaration_instantiation(nullptr));
auto result_and_frame = bytecode_interpreter->run_and_return_frame(*m_bytecode_executable, nullptr);
VERIFY(result_and_frame.frame != nullptr);
if (result_and_frame.value.is_error())
return result_and_frame.value.release_error();
auto result = result_and_frame.value.release_value();
// NOTE: Running the bytecode should eventually return a completion.
// Until it does, we assume "return" and include the undefined fallback from the call site.
if (m_kind == FunctionKind::Normal)
return { Completion::Type::Return, result.value_or(js_undefined()), {} };
auto generator_object = TRY(GeneratorObject::create(realm, result, this, vm.running_execution_context().copy(), move(*result_and_frame.frame)));
// NOTE: Async functions are entirely transformed to generator functions, and wrapped in a custom driver that returns a promise
// See AwaitExpression::generate_bytecode() for the transformation.
if (m_kind == FunctionKind::Async)
return { Completion::Type::Return, TRY(AsyncFunctionDriverWrapper::create(realm, generator_object)), {} };
VERIFY(m_kind == FunctionKind::Generator);
return { Completion::Type::Return, generator_object, {} };
} else {
if (m_kind == FunctionKind::Generator)
return vm.throw_completion<InternalError>(ErrorType::NotImplemented, "Generator function execution in AST interpreter");
OwnPtr<Interpreter> local_interpreter;
Interpreter* ast_interpreter = vm.interpreter_if_exists();
if (!ast_interpreter) {
local_interpreter = Interpreter::create_with_existing_realm(realm);
ast_interpreter = local_interpreter.ptr();
}
VM::InterpreterExecutionScope scope(*ast_interpreter);
// FunctionBody : FunctionStatementList
if (m_kind == FunctionKind::Normal) {
// 1. Perform ? FunctionDeclarationInstantiation(functionObject, argumentsList).
TRY(function_declaration_instantiation(ast_interpreter));
// 2. Let result be result of evaluating FunctionStatementList.
auto result = m_ecmascript_code->execute(*ast_interpreter);
// 3. Let env be the running execution context's LexicalEnvironment.
auto* env = vm.running_execution_context().lexical_environment;
VERIFY(is<DeclarativeEnvironment>(env));
// 4. Return ? DisposeResources(env, result).
return dispose_resources(vm, static_cast<DeclarativeEnvironment*>(env), result);
}
// AsyncFunctionBody : FunctionBody
else if (m_kind == FunctionKind::Async) {
// 1. Let promiseCapability be ! NewPromiseCapability(%Promise%).
auto promise_capability = MUST(new_promise_capability(vm, realm.intrinsics().promise_constructor()));
// 2. Let declResult be Completion(FunctionDeclarationInstantiation(functionObject, argumentsList)).
auto declaration_result = function_declaration_instantiation(ast_interpreter);
// 3. If declResult is an abrupt completion, then
if (declaration_result.is_throw_completion()) {
// a. Perform ! Call(promiseCapability.[[Reject]], undefined, « declResult.[[Value]] »).
MUST(call(vm, *promise_capability->reject(), js_undefined(), *declaration_result.throw_completion().value()));
}
// 4. Else,
else {
// a. Perform AsyncFunctionStart(promiseCapability, FunctionBody).
async_function_start(promise_capability);
}
// 5. Return Completion Record { [[Type]]: return, [[Value]]: promiseCapability.[[Promise]], [[Target]]: empty }.
return Completion { Completion::Type::Return, promise_capability->promise(), {} };
}
}
VERIFY_NOT_REACHED();
}
void ECMAScriptFunctionObject::set_name(DeprecatedFlyString const& name)
{
VERIFY(!name.is_null());
auto& vm = this->vm();
m_name = name;
MUST(define_property_or_throw(vm.names.name, { .value = PrimitiveString::create(vm, m_name), .writable = false, .enumerable = false, .configurable = true }));
}
}
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