/*
* Copyright (c) 2020, Stephan Unverwerth <s.unverwerth@serenityos.org>
* Copyright (c) 2020-2023, Linus Groh <linusg@serenityos.org>
* Copyright (c) 2023, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2023, Shannon Booth <shannon@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/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/AsyncFunctionDriverWrapper.h>
#include <LibJS/Runtime/AsyncGenerator.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/GlobalEnvironment.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 {
JS_DEFINE_ALLOCATOR(ECMAScriptFunctionObject);
NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, 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, move(local_variables_names), 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, Vector<DeprecatedFlyString> local_variables_names, 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, move(local_variables_names), 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, Vector<DeprecatedFlyString> local_variables_names, 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_local_variables_names(move(local_variables_names))
, 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<NonnullRefPtr<Identifier const>>())
return false;
return true;
});
// NOTE: The following steps are from FunctionDeclarationInstantiation that could be executed once
// and then reused in all subsequent function instantiations.
// 2. Let code be func.[[ECMAScriptCode]].
ScopeNode const* scope_body = nullptr;
if (is<ScopeNode>(*m_ecmascript_code))
scope_body = static_cast<ScopeNode const*>(m_ecmascript_code.ptr());
// 3. Let strict be func.[[Strict]].
// 4. Let formals be func.[[FormalParameters]].
auto const& formals = m_formal_parameters;
// 5. Let parameterNames be the BoundNames of formals.
// 6. If parameterNames has any duplicate entries, let hasDuplicates be true. Otherwise, let hasDuplicates be false.
// NOTE: This loop performs step 5, 6, and 8.
for (auto const& parameter : formals) {
if (parameter.default_value)
m_has_parameter_expressions = true;
parameter.binding.visit(
[&](Identifier const& identifier) {
if (m_parameter_names.set(identifier.string()) != AK::HashSetResult::InsertedNewEntry)
m_has_duplicates = true;
},
[&](NonnullRefPtr<BindingPattern const> const& pattern) {
if (pattern->contains_expression())
m_has_parameter_expressions = true;
// NOTE: Nothing in the callback throws an exception.
MUST(pattern->for_each_bound_identifier([&](auto& identifier) {
if (m_parameter_names.set(identifier.string()) != AK::HashSetResult::InsertedNewEntry)
m_has_duplicates = true;
}));
});
}
// 15. Let argumentsObjectNeeded be true.
m_arguments_object_needed = m_might_need_arguments_object;
// 16. If func.[[ThisMode]] is lexical, then
if (this_mode() == ThisMode::Lexical) {
// a. NOTE: Arrow functions never have an arguments object.
// b. Set argumentsObjectNeeded to false.
m_arguments_object_needed = false;
}
// 17. Else if parameterNames contains "arguments", then
else if (m_parameter_names.contains(vm().names.arguments.as_string())) {
// a. Set argumentsObjectNeeded to false.
m_arguments_object_needed = false;
}
HashTable<DeprecatedFlyString> function_names;
// 18. Else if hasParameterExpressions is false, then
// a. If functionNames contains "arguments" or lexicalNames contains "arguments", then
// i. Set argumentsObjectNeeded to false.
// NOTE: The block below is a combination of step 14 and step 18.
if (scope_body) {
// NOTE: Nothing in the callback throws an exception.
MUST(scope_body->for_each_var_function_declaration_in_reverse_order([&](FunctionDeclaration const& function) {
if (function_names.set(function.name()) == AK::HashSetResult::InsertedNewEntry)
m_functions_to_initialize.append(function);
}));
auto const& arguments_name = vm().names.arguments.as_string();
if (!m_has_parameter_expressions && function_names.contains(arguments_name))
m_arguments_object_needed = false;
if (!m_has_parameter_expressions && m_arguments_object_needed) {
// NOTE: Nothing in the callback throws an exception.
MUST(scope_body->for_each_lexically_declared_identifier([&](auto const& identifier) {
if (identifier.string() == arguments_name)
m_arguments_object_needed = false;
}));
}
} else {
m_arguments_object_needed = false;
}
size_t* environment_size = nullptr;
size_t parameter_environment_bindings_count = 0;
// 19. If strict is true or hasParameterExpressions is false, then
if (m_strict || !m_has_parameter_expressions) {
// a. NOTE: Only a single Environment Record is needed for the parameters, since calls to eval in strict mode code cannot create new bindings which are visible outside of the eval.
// b. Let env be the LexicalEnvironment of calleeContext
// NOTE: Here we are only interested in the size of the environment.
environment_size = &m_function_environment_bindings_count;
}
// 20. Else,
else {
// a. NOTE: A separate Environment Record is needed to ensure that bindings created by direct eval calls in the formal parameter list are outside the environment where parameters are declared.
// b. Let calleeEnv be the LexicalEnvironment of calleeContext.
// c. Let env be NewDeclarativeEnvironment(calleeEnv).
environment_size = ¶meter_environment_bindings_count;
}
*environment_size += m_parameter_names.size();
HashTable<DeprecatedFlyString> parameter_bindings;
// 22. If argumentsObjectNeeded is true, then
if (m_arguments_object_needed) {
// f. Let parameterBindings be the list-concatenation of parameterNames and « "arguments" ».
parameter_bindings = m_parameter_names;
parameter_bindings.set(vm().names.arguments.as_string());
(*environment_size)++;
} else {
parameter_bindings = m_parameter_names;
// a. Let parameterBindings be parameterNames.
}
HashTable<DeprecatedFlyString> instantiated_var_names;
size_t* var_environment_size = nullptr;
// 27. If hasParameterExpressions is false, then
if (!m_has_parameter_expressions) {
// b. Let instantiatedVarNames be a copy of the List parameterBindings.
instantiated_var_names = parameter_bindings;
if (scope_body) {
// c. For each element n of varNames, do
MUST(scope_body->for_each_var_declared_identifier([&](auto const& id) {
// i. If instantiatedVarNames does not contain n, then
if (instantiated_var_names.set(id.string()) == AK::HashSetResult::InsertedNewEntry) {
// 1. Append n to instantiatedVarNames.
// Following steps will be executed in function_declaration_instantiation:
// 2. Perform ! env.CreateMutableBinding(n, false).
// 3. Perform ! env.InitializeBinding(n, undefined).
m_var_names_to_initialize_binding.append({
.identifier = id,
.parameter_binding = parameter_bindings.contains(id.string()),
.function_name = function_names.contains(id.string()),
});
if (!id.is_local())
(*environment_size)++;
}
}));
}
// d. Let varEnv be env
var_environment_size = environment_size;
} else {
// a. NOTE: A separate Environment Record is needed to ensure that closures created by expressions in the formal parameter list do not have visibility of declarations in the function body.
// b. Let varEnv be NewDeclarativeEnvironment(env).
// NOTE: Here we are only interested in the size of the environment.
var_environment_size = &m_var_environment_bindings_count;
// 28. Else,
// NOTE: Steps a, b, c and d are executed in function_declaration_instantiation.
// e. For each element n of varNames, do
if (scope_body) {
MUST(scope_body->for_each_var_declared_identifier([&](auto const& id) {
// 1. Append n to instantiatedVarNames.
// Following steps will be executed in function_declaration_instantiation:
// 2. Perform ! env.CreateMutableBinding(n, false).
// 3. Perform ! env.InitializeBinding(n, undefined).
if (instantiated_var_names.set(id.string()) == AK::HashSetResult::InsertedNewEntry) {
m_var_names_to_initialize_binding.append({
.identifier = id,
.parameter_binding = parameter_bindings.contains(id.string()),
.function_name = function_names.contains(id.string()),
});
if (!id.is_local())
(*var_environment_size)++;
}
}));
}
}
// 29. NOTE: Annex B.3.2.1 adds additional steps at this point.
// B.3.2.1 Changes to FunctionDeclarationInstantiation, https://tc39.es/ecma262/#sec-web-compat-functiondeclarationinstantiation
if (!m_strict && scope_body) {
MUST(scope_body->for_each_function_hoistable_with_annexB_extension([&](FunctionDeclaration& function_declaration) {
auto function_name = function_declaration.name();
if (parameter_bindings.contains(function_name))
return;
if (!instantiated_var_names.contains(function_name) && function_name != vm().names.arguments.as_string()) {
m_function_names_to_initialize_binding.append(function_name);
instantiated_var_names.set(function_name);
(*var_environment_size)++;
}
function_declaration.set_should_do_additional_annexB_steps();
}));
}
size_t* lex_environment_size = nullptr;
// 30. If strict is false, then
if (!m_strict) {
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_size = var_environment_size;
} else {
// a. Let lexEnv be NewDeclarativeEnvironment(varEnv).
lex_environment_size = &m_lex_environment_bindings_count;
}
} else {
// a. let lexEnv be varEnv.
// NOTE: Here we are only interested in the size of the environment.
lex_environment_size = var_environment_size;
}
if (scope_body) {
MUST(scope_body->for_each_lexically_declared_identifier([&](auto const& id) {
if (!id.is_local())
(*lex_environment_size)++;
}));
}
}
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.
m_name_string = PrimitiveString::create(vm, m_name);
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 = m_name_string, .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, ReadonlySpan<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.
auto callee_context = ExecutionContext::create(heap());
callee_context->locals.resize(m_local_variables_names.size());
// Non-standard
callee_context->arguments.append(arguments_list.data(), arguments_list.size());
callee_context->instruction_stream_iterator = vm.bytecode_interpreter().instruction_stream_iterator();
// 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(ReadonlySpan<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));
}
auto callee_context = ExecutionContext::create(heap());
callee_context->locals.resize(m_local_variables_names.size());
// Non-standard
callee_context->arguments.append(arguments_list.data(), arguments_list.size());
callee_context->instruction_stream_iterator = vm.bytecode_interpreter().instruction_stream_iterator();
// 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);
visitor.visit(m_bytecode_executable);
for (auto& executable : m_default_parameter_bytecode_executables)
visitor.visit(executable);
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);
});
}
// 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()
{
auto& vm = this->vm();
auto& realm = *vm.current_realm();
// 1. Let calleeContext be the running execution context.
auto& callee_context = vm.running_execution_context();
// 2. Let code be func.[[ECMAScriptCode]].
ScopeNode const* scope_body = nullptr;
if (is<ScopeNode>(*m_ecmascript_code))
scope_body = static_cast<ScopeNode const*>(m_ecmascript_code.ptr());
// NOTE: Following steps were executed in ECMAScriptFunctionObject constructor.
// 3. Let strict be func.[[Strict]].
// 4. Let formals be func.[[FormalParameters]].
// 5. Let parameterNames be the BoundNames of formals.
// 6. If parameterNames has any duplicate entries, let hasDuplicates be true. Otherwise, let hasDuplicates be false.
// 7. Let simpleParameterList be IsSimpleParameterList of formals.
bool const simple_parameter_list = has_simple_parameter_list();
// NOTE: Following steps were executed in ECMAScriptFunctionObject constructor.
// 8. Let hasParameterExpressions be ContainsExpression of formals.
// 9. Let varNames be the VarDeclaredNames of code.
// 10. Let varDeclarations be the VarScopedDeclarations of code.
// 11. Let lexicalNames be the LexicallyDeclaredNames of code.
// 12. Let functionNames be a new empty List.
// 13. Let functionsToInitialize be a new empty List.
// 14. For each element d of varDeclarations, in reverse List order, do
// 15. Let argumentsObjectNeeded be true.
// 16. If func.[[ThisMode]] is lexical, then
// 17. Else if parameterNames contains "arguments", then
// 18. Else if hasParameterExpressions is false, then
GCPtr<Environment> environment;
// 19. If strict is true or hasParameterExpressions is false, then
if (m_strict || !m_has_parameter_expressions) {
// a. NOTE: Only a single Environment Record is needed for the parameters, since calls to eval in strict mode code cannot create new bindings which are visible outside of the eval.
// b. Let env be the LexicalEnvironment of calleeContext.
environment = callee_context.lexical_environment;
}
// 20. Else,
else {
// a. NOTE: A separate Environment Record is needed to ensure that bindings created by direct eval calls in the formal parameter list are outside the environment where parameters are declared.
// b. Let calleeEnv be the LexicalEnvironment of calleeContext.
auto callee_env = callee_context.lexical_environment;
// c. Let env be NewDeclarativeEnvironment(calleeEnv).
environment = new_declarative_environment(*callee_env);
// d. Assert: The VariableEnvironment of calleeContext is calleeEnv.
VERIFY(callee_context.variable_environment == callee_context.lexical_environment);
// e. Set the LexicalEnvironment of calleeContext to env.
callee_context.lexical_environment = environment;
}
// 21. For each String paramName of parameterNames, do
for (auto const& parameter_name : m_parameter_names) {
// a. Let alreadyDeclared be ! env.HasBinding(paramName).
// b. NOTE: Early errors ensure that duplicate parameter names can only occur in non-strict functions that do not have parameter default values or rest parameters.
// c. If alreadyDeclared is false, then
// NOTE: alreadyDeclared is always false because we use hash table for parameterNames
// i. Perform ! env.CreateMutableBinding(paramName, false).
MUST(environment->create_mutable_binding(vm, parameter_name, false));
// ii. If hasDuplicates is true, then
if (m_has_duplicates) {
// 1. Perform ! env.InitializeBinding(paramName, undefined).
MUST(environment->initialize_binding(vm, parameter_name, js_undefined(), Environment::InitializeBindingHint::Normal));
}
}
// 22. If argumentsObjectNeeded is true, then
if (m_arguments_object_needed) {
Object* arguments_object;
// a. If strict is true or simpleParameterList is false, then
if (m_strict || !simple_parameter_list) {
// i. Let ao be CreateUnmappedArgumentsObject(argumentsList).
arguments_object = create_unmapped_arguments_object(vm, vm.running_execution_context().arguments);
}
// b. Else,
else {
// i. NOTE: A mapped argument object is only provided for non-strict functions that don't have a rest parameter, any parameter default value initializers, or any destructured parameters.
// ii. Let ao be CreateMappedArgumentsObject(func, formals, argumentsList, env).
arguments_object = create_mapped_arguments_object(vm, *this, formal_parameters(), vm.running_execution_context().arguments, *environment);
}
// c. If strict is true, then
if (m_strict) {
// i. Perform ! env.CreateImmutableBinding("arguments", false).
MUST(environment->create_immutable_binding(vm, vm.names.arguments.as_string(), false));
// ii. NOTE: In strict mode code early errors prevent attempting to assign to this binding, so its mutability is not observable.
}
// b. Else,
else {
// i. Perform ! env.CreateMutableBinding("arguments", false).
MUST(environment->create_mutable_binding(vm, vm.names.arguments.as_string(), false));
}
// c. Perform ! env.InitializeBinding("arguments", ao).
MUST(environment->initialize_binding(vm, vm.names.arguments.as_string(), arguments_object, Environment::InitializeBindingHint::Normal));
// f. Let parameterBindings be the list-concatenation of parameterNames and « "arguments" ».
}
// 23. Else,
else {
// a. Let parameterBindings be parameterNames.
}
// NOTE: We now treat parameterBindings as parameterNames.
// 24. Let iteratorRecord be CreateListIteratorRecord(argumentsList).
// 25. If hasDuplicates is true, then
// a. Perform ? IteratorBindingInitialization of formals with arguments iteratorRecord and undefined.
// 26. Else,
// a. Perform ? IteratorBindingInitialization of formals with arguments iteratorRecord and env.
// NOTE: 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) {
auto value_and_frame = vm.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()[0];
} else {
argument_value = js_undefined();
}
Environment* used_environment = m_has_duplicates ? nullptr : environment;
if constexpr (IsSame<NonnullRefPtr<Identifier const> const&, decltype(param)>) {
if (param->is_local()) {
callee_context.locals[param->local_variable_index()] = argument_value;
return {};
}
Reference reference = TRY(vm.resolve_binding(param->string(), used_environment));
// Here the difference from hasDuplicates is important
if (m_has_duplicates)
return reference.put_value(vm, argument_value);
return reference.initialize_referenced_binding(vm, argument_value);
}
if constexpr (IsSame<NonnullRefPtr<BindingPattern const> const&, decltype(param)>) {
// Here the difference from hasDuplicates is important
return vm.binding_initialization(param, argument_value, used_environment);
}
}));
}
GCPtr<Environment> var_environment;
// 27. If hasParameterExpressions is false, then
if (!m_has_parameter_expressions) {
// a. NOTE: Only a single Environment Record is needed for the parameters and top-level vars.
// b. Let instantiatedVarNames be a copy of the List parameterBindings.
// NOTE: Done in implementation of step 27.c.i.1 below
if (scope_body) {
// NOTE: Due to the use of MUST with `create_mutable_binding` and `initialize_binding` below,
// an exception should not result from `for_each_var_declared_name`.
// c. For each element n of varNames, do
for (auto const& variable_to_initialize : m_var_names_to_initialize_binding) {
auto const& id = variable_to_initialize.identifier;
// NOTE: Following steps were executed in ECMAScriptFunctionObject constructor.
// i. If instantiatedVarNames does not contain n, then
// 1. Append n to instantiatedVarNames.
if (id.is_local()) {
callee_context.locals[id.local_variable_index()] = js_undefined();
} else {
// 2. Perform ! env.CreateMutableBinding(n, false).
// 3. Perform ! env.InitializeBinding(n, undefined).
MUST(environment->create_mutable_binding(vm, id.string(), false));
MUST(environment->initialize_binding(vm, id.string(), js_undefined(), Environment::InitializeBindingHint::Normal));
}
}
}
// d.Let varEnv be env
var_environment = environment;
}
// 28. Else,
else {
// a. NOTE: A separate Environment Record is needed to ensure that closures created by expressions in the formal parameter list do not have visibility of declarations in the function body.
// b. Let varEnv be NewDeclarativeEnvironment(env).
var_environment = new_declarative_environment(*environment);
static_cast<DeclarativeEnvironment*>(var_environment.ptr())->ensure_capacity(m_var_environment_bindings_count);
// c. Set the VariableEnvironment of calleeContext to varEnv.
callee_context.variable_environment = var_environment;
// d. Let instantiatedVarNames be a new empty List.
// NOTE: Already done above.
if (scope_body) {
// NOTE: Due to the use of MUST with `create_mutable_binding`, `get_binding_value` and `initialize_binding` below,
// an exception should not result from `for_each_var_declared_name`.
// e. For each element n of varNames, do
for (auto const& variable_to_initialize : m_var_names_to_initialize_binding) {
auto const& id = variable_to_initialize.identifier;
// NOTE: Following steps were executed in ECMAScriptFunctionObject constructor.
// i. If instantiatedVarNames does not contain n, then
// 1. Append n to instantiatedVarNames.
// 2. Perform ! varEnv.CreateMutableBinding(n, false).
// NOTE: We ignore locals because they are stored in ExecutionContext instead of environment.
if (!id.is_local())
MUST(var_environment->create_mutable_binding(vm, id.string(), false));
Value initial_value;
// 3. If parameterBindings does not contain n, or if functionNames contains n, then
if (!variable_to_initialize.parameter_binding || variable_to_initialize.function_name) {
// a. Let initialValue be undefined.
initial_value = js_undefined();
}
// 4. Else,
else {
// a. Let initialValue be ! env.GetBindingValue(n, false).
if (id.is_local()) {
initial_value = callee_context.locals[id.local_variable_index()];
} else {
initial_value = MUST(environment->get_binding_value(vm, id.string(), false));
}
}
// 5. Perform ! varEnv.InitializeBinding(n, initialValue).
if (id.is_local()) {
// NOTE: Local variables are supported only in bytecode interpreter
callee_context.locals[id.local_variable_index()] = initial_value;
} else {
MUST(var_environment->initialize_binding(vm, id.string(), initial_value, Environment::InitializeBindingHint::Normal));
}
// 6. NOTE: A var with the same name as a formal parameter initially has the same value as the corresponding initialized parameter.
}
}
}
// 29. NOTE: Annex B.3.2.1 adds additional steps at this point.
// B.3.2.1 Changes to FunctionDeclarationInstantiation, https://tc39.es/ecma262/#sec-web-compat-functiondeclarationinstantiation
if (!m_strict && scope_body) {
// NOTE: Due to the use of MUST with `create_mutable_binding` and `initialize_binding` below,
// an exception should not result from `for_each_function_hoistable_with_annexB_extension`.
for (auto const& function_name : m_function_names_to_initialize_binding) {
MUST(var_environment->create_mutable_binding(vm, function_name, false));
MUST(var_environment->initialize_binding(vm, function_name, js_undefined(), Environment::InitializeBindingHint::Normal));
}
}
GCPtr<Environment> lex_environment;
// 30. If strict is false, then
if (!m_strict) {
// 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);
static_cast<DeclarativeEnvironment*>(lex_environment.ptr())->ensure_capacity(m_lex_environment_bindings_count);
}
}
// 31. Else,
else {
// a. 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 {};
// 33. Let lexDeclarations be the LexicallyScopedDeclarations of code.
// 34. For each element d of lexDeclarations, do
// NOTE: Due to the use of MUST in the callback, an exception should not result from `for_each_lexically_scoped_declaration`.
MUST(scope_body->for_each_lexically_scoped_declaration([&](Declaration const& declaration) {
// NOTE: Due to the use of MUST with `create_immutable_binding` and `create_mutable_binding` below,
// an exception should not result from `for_each_bound_name`.
// a. NOTE: A lexically declared name cannot be the same as a function/generator declaration, formal parameter, or a var name. Lexically declared names are only instantiated here but not initialized.
// b. For each element dn of the BoundNames of d, do
MUST(declaration.for_each_bound_identifier([&](auto const& id) {
if (id.is_local()) {
// NOTE: Local variables are supported only in bytecode interpreter
return;
}
// i. If IsConstantDeclaration of d is true, then
if (declaration.is_constant_declaration()) {
// 1. Perform ! lexEnv.CreateImmutableBinding(dn, true).
MUST(lex_environment->create_immutable_binding(vm, id.string(), true));
}
// ii. Else,
else {
// 1. Perform ! lexEnv.CreateMutableBinding(dn, false).
MUST(lex_environment->create_mutable_binding(vm, id.string(), false));
}
}));
}));
// 35. Let privateEnv be the PrivateEnvironment of calleeContext.
auto private_environment = callee_context.private_environment;
// 36. For each Parse Node f of functionsToInitialize, do
for (auto& declaration : m_functions_to_initialize) {
// a. Let fn be the sole element of the BoundNames of f.
// b. Let fo be InstantiateFunctionObject of f with arguments lexEnv and privateEnv.
auto function = ECMAScriptFunctionObject::create(realm, declaration.name(), declaration.source_text(), declaration.body(), declaration.parameters(), declaration.function_length(), declaration.local_variables_names(), lex_environment, private_environment, declaration.kind(), declaration.is_strict_mode(), declaration.might_need_arguments_object(), declaration.contains_direct_call_to_eval());
// c. Perform ! varEnv.SetMutableBinding(fn, fo, false).
if (declaration.name_identifier()->is_local()) {
callee_context.locals[declaration.name_identifier()->local_variable_index()] = function;
} else {
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();
// 37. Return unused.
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_string;
// 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);
local_environment->ensure_capacity(m_function_environment_bindings_count);
// 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
template<typename T>
void async_function_start(VM& vm, PromiseCapability const& promise_capability, T const& async_function_body)
{
// 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, async_function_body, promise_capability, *async_context);
// 5. Return unused.
}
// 27.7.5.2 AsyncBlockStart ( promiseCapability, asyncBody, asyncContext ), https://tc39.es/ecma262/#sec-asyncblockstart
// 12.7.1.1 AsyncBlockStart ( promiseCapability, asyncBody, asyncContext ), https://tc39.es/proposal-explicit-resource-management/#sec-asyncblockstart
// 1.2.1.1 AsyncBlockStart ( promiseCapability, asyncBody, asyncContext ), https://tc39.es/proposal-array-from-async/#sec-asyncblockstart
template<typename T>
void async_block_start(VM& vm, T const& async_body, PromiseCapability const& promise_capability, ExecutionContext& async_context)
{
// NOTE: This function is a combination between two proposals, so does not exactly match spec steps of either.
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> {
Completion result;
// a. If asyncBody is a Parse Node, then
if constexpr (!IsCallableWithArguments<T, Completion>) {
// a. Let result be the result of evaluating asyncBody.
// FIXME: Cache this executable somewhere.
auto maybe_executable = Bytecode::compile(vm, async_body, FunctionKind::Async, "AsyncBlockStart"sv);
if (maybe_executable.is_error())
result = maybe_executable.release_error();
else
result = vm.bytecode_interpreter().run_and_return_frame(*maybe_executable.value(), nullptr).value;
}
// b. Else,
else {
// i. Assert: asyncBody is an Abstract Closure with no parameters.
static_assert(IsCallableWithArguments<T, Completion>);
// ii. Let result be asyncBody().
result = async_body();
}
// c. Assert: If we return here, the async function either threw an exception or performed an implicit or explicit return; all awaiting is done.
// d. 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();
// NOTE: This does not work for Array.fromAsync, likely due to conflicts between that proposal and Explicit Resource Management proposal.
if constexpr (!IsCallableWithArguments<T, Completion>) {
// e. Let env be asyncContext's LexicalEnvironment.
auto env = async_context.lexical_environment;
// f. Set result to DisposeResources(env, result).
result = dispose_resources(vm, verify_cast<DeclarativeEnvironment>(env.ptr()), result);
} else {
(void)async_context;
}
// g. 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()));
}
// h. 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()));
}
// i. 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()));
}
// j. 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.
}
template void async_block_start(VM&, NonnullRefPtr<Statement const> const& async_body, PromiseCapability const&, ExecutionContext&);
template void async_function_start(VM&, PromiseCapability const&, NonnullRefPtr<Statement const> const& async_function_body);
template void async_block_start(VM&, SafeFunction<Completion()> const& async_body, PromiseCapability const&, ExecutionContext&);
template void async_function_start(VM&, PromiseCapability const&, SafeFunction<Completion()> const& async_function_body);
// 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();
// NOTE: There's a subtle ordering issue here:
// - We have to compile the default parameter values before instantiating the function.
// - We have to instantiate the function before compiling the function body.
// This is why FunctionDeclarationInstantiation is invoked in the middle.
// The issue is that FunctionDeclarationInstantiation may mark certain functions as hoisted
// per Annex B. This affects code generation for FunctionDeclaration nodes.
if (!m_bytecode_executable) {
size_t default_parameter_index = 0;
for (auto& parameter : m_formal_parameters) {
if (!parameter.default_value)
continue;
if (parameter.bytecode_executable.is_null()) {
auto executable = TRY(Bytecode::compile(vm, *parameter.default_value, FunctionKind::Normal, DeprecatedString::formatted("default parameter #{} for {}", default_parameter_index++, m_name)));
const_cast<FunctionParameter&>(parameter).bytecode_executable = executable;
m_default_parameter_bytecode_executables.append(move(executable));
} else {
m_default_parameter_bytecode_executables.append(*parameter.bytecode_executable);
}
}
}
auto declaration_result = function_declaration_instantiation();
if (m_kind == FunctionKind::Normal || m_kind == FunctionKind::Generator || m_kind == FunctionKind::AsyncGenerator) {
if (declaration_result.is_error())
return declaration_result.release_error();
}
if (!m_bytecode_executable) {
if (!m_ecmascript_code->bytecode_executable())
const_cast<Statement&>(*m_ecmascript_code).set_bytecode_executable(TRY(Bytecode::compile(vm, *m_ecmascript_code, m_kind, m_name)));
m_bytecode_executable = m_ecmascript_code->bytecode_executable();
}
if (m_kind == FunctionKind::Async) {
if (declaration_result.is_throw_completion()) {
auto promise_capability = MUST(new_promise_capability(vm, realm.intrinsics().promise_constructor()));
MUST(call(vm, *promise_capability->reject(), js_undefined(), *declaration_result.throw_completion().value()));
return Completion { Completion::Type::Return, promise_capability->promise(), {} };
}
}
auto result_and_frame = vm.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()), {} };
if (m_kind == FunctionKind::AsyncGenerator) {
auto async_generator_object = TRY(AsyncGenerator::create(realm, result, this, vm.running_execution_context().copy(), result_and_frame.frame.release_nonnull()));
return { Completion::Type::Return, async_generator_object, {} };
}
auto generator_object = TRY(GeneratorObject::create(realm, result, this, vm.running_execution_context().copy(), result_and_frame.frame.release_nonnull()));
// 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, AsyncFunctionDriverWrapper::create(realm, generator_object), {} };
VERIFY(m_kind == FunctionKind::Generator);
return { Completion::Type::Return, generator_object, {} };
}
void ECMAScriptFunctionObject::set_name(DeprecatedFlyString const& name)
{
VERIFY(!name.is_null());
auto& vm = this->vm();
m_name = name;
m_name_string = PrimitiveString::create(vm, m_name);
MUST(define_property_or_throw(vm.names.name, { .value = m_name_string, .writable = false, .enumerable = false, .configurable = true }));
}
}