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	I wanted to do this for a long time. The guts of Promise are pretty complex, and it's easier to understand with the spec right next to it. Also found a couple of issues along the way :^)
		
			
				
	
	
		
			200 lines
		
	
	
	
		
			8.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			200 lines
		
	
	
	
		
			8.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
/*
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 * Copyright (c) 2021, Tim Flynn <trflynn89@pm.me>
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 *
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 * SPDX-License-Identifier: BSD-2-Clause
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 */
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#include <LibJS/Runtime/AbstractOperations.h>
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#include <LibJS/Runtime/AggregateError.h>
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#include <LibJS/Runtime/Array.h>
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#include <LibJS/Runtime/GlobalObject.h>
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#include <LibJS/Runtime/PromiseReaction.h>
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#include <LibJS/Runtime/PromiseResolvingElementFunctions.h>
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namespace JS {
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PromiseResolvingElementFunction::PromiseResolvingElementFunction(size_t index, PromiseValueList& values, PromiseCapability capability, RemainingElements& remaining_elements, Object& prototype)
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    : NativeFunction(prototype)
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    , m_index(index)
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    , m_values(values)
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    , m_capability(move(capability))
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    , m_remaining_elements(remaining_elements)
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{
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}
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void PromiseResolvingElementFunction::initialize(GlobalObject& global_object)
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{
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    Base::initialize(global_object);
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    define_direct_property(vm().names.length, Value(1), Attribute::Configurable);
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}
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ThrowCompletionOr<Value> PromiseResolvingElementFunction::call()
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{
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    if (m_already_called)
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        return js_undefined();
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    m_already_called = true;
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    return resolve_element();
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}
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void PromiseResolvingElementFunction::visit_edges(Cell::Visitor& visitor)
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{
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    Base::visit_edges(visitor);
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    visitor.visit(&m_values);
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    visitor.visit(m_capability.promise);
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    visitor.visit(m_capability.resolve);
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    visitor.visit(m_capability.reject);
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    visitor.visit(&m_remaining_elements);
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}
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PromiseAllResolveElementFunction* PromiseAllResolveElementFunction::create(GlobalObject& global_object, size_t index, PromiseValueList& values, PromiseCapability capability, RemainingElements& remaining_elements)
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{
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    return global_object.heap().allocate<PromiseAllResolveElementFunction>(global_object, index, values, capability, remaining_elements, *global_object.function_prototype());
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}
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PromiseAllResolveElementFunction::PromiseAllResolveElementFunction(size_t index, PromiseValueList& values, PromiseCapability capability, RemainingElements& remaining_elements, Object& prototype)
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    : PromiseResolvingElementFunction(index, values, move(capability), remaining_elements, prototype)
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{
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}
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Value PromiseAllResolveElementFunction::resolve_element()
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{
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    auto& vm = this->vm();
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    auto& global_object = this->global_object();
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    // 8. Set values[index] to x.
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    m_values.values()[m_index] = vm.argument(0);
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    // 9. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
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    // 10. If remainingElementsCount.[[Value]] is 0, then
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    if (--m_remaining_elements.value == 0) {
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        // a. Let valuesArray be ! CreateArrayFromList(values).
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        auto* values_array = Array::create_from(global_object, m_values.values());
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        // b. Return ? Call(promiseCapability.[[Resolve]], undefined, « valuesArray »).
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        return TRY_OR_DISCARD(vm.call(*m_capability.resolve, js_undefined(), values_array));
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    }
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    // 11. Return undefined.
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    return js_undefined();
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}
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PromiseAllSettledResolveElementFunction* PromiseAllSettledResolveElementFunction::create(GlobalObject& global_object, size_t index, PromiseValueList& values, PromiseCapability capability, RemainingElements& remaining_elements)
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{
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    return global_object.heap().allocate<PromiseAllSettledResolveElementFunction>(global_object, index, values, capability, remaining_elements, *global_object.function_prototype());
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}
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PromiseAllSettledResolveElementFunction::PromiseAllSettledResolveElementFunction(size_t index, PromiseValueList& values, PromiseCapability capability, RemainingElements& remaining_elements, Object& prototype)
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    : PromiseResolvingElementFunction(index, values, move(capability), remaining_elements, prototype)
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{
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}
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Value PromiseAllSettledResolveElementFunction::resolve_element()
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{
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    auto& vm = this->vm();
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    auto& global_object = this->global_object();
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    // 9. Let obj be ! OrdinaryObjectCreate(%Object.prototype%).
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    auto* object = Object::create(global_object, global_object.object_prototype());
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    // 10. Perform ! CreateDataPropertyOrThrow(obj, "status", "fulfilled").
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    MUST(object->create_data_property_or_throw(vm.names.status, js_string(vm, "fulfilled"sv)));
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    // 11. Perform ! CreateDataPropertyOrThrow(obj, "value", x).
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    MUST(object->create_data_property_or_throw(vm.names.value, vm.argument(0)));
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    // 12. Set values[index] to obj.
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    m_values.values()[m_index] = object;
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    // 13. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
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    // 14. If remainingElementsCount.[[Value]] is 0, then
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    if (--m_remaining_elements.value == 0) {
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        // a. Let valuesArray be ! CreateArrayFromList(values).
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        auto* values_array = Array::create_from(global_object, m_values.values());
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        // b. Return ? Call(promiseCapability.[[Resolve]], undefined, « valuesArray »).
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        return TRY_OR_DISCARD(vm.call(*m_capability.resolve, js_undefined(), values_array));
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    }
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    // 15. Return undefined.
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    return js_undefined();
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}
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PromiseAllSettledRejectElementFunction* PromiseAllSettledRejectElementFunction::create(GlobalObject& global_object, size_t index, PromiseValueList& values, PromiseCapability capability, RemainingElements& remaining_elements)
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{
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    return global_object.heap().allocate<PromiseAllSettledRejectElementFunction>(global_object, index, values, capability, remaining_elements, *global_object.function_prototype());
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}
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PromiseAllSettledRejectElementFunction::PromiseAllSettledRejectElementFunction(size_t index, PromiseValueList& values, PromiseCapability capability, RemainingElements& remaining_elements, Object& prototype)
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    : PromiseResolvingElementFunction(index, values, move(capability), remaining_elements, prototype)
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{
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}
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Value PromiseAllSettledRejectElementFunction::resolve_element()
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{
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    auto& vm = this->vm();
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    auto& global_object = this->global_object();
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    // 9. Let obj be ! OrdinaryObjectCreate(%Object.prototype%).
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    auto* object = Object::create(global_object, global_object.object_prototype());
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    // 10. Perform ! CreateDataPropertyOrThrow(obj, "status", "rejected").
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    MUST(object->create_data_property_or_throw(vm.names.status, js_string(vm, "rejected"sv)));
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    // 11. Perform ! CreateDataPropertyOrThrow(obj, "reason", x).
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    MUST(object->create_data_property_or_throw(vm.names.reason, vm.argument(0)));
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    // 12. Set values[index] to obj.
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    m_values.values()[m_index] = object;
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    // 13. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
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    // 14. If remainingElementsCount.[[Value]] is 0, then
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    if (--m_remaining_elements.value == 0) {
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        // a. Let valuesArray be ! CreateArrayFromList(values).
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        auto values_array = Array::create_from(global_object, m_values.values());
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        // b. Return ? Call(promiseCapability.[[Resolve]], undefined, « valuesArray »).
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        return TRY_OR_DISCARD(vm.call(*m_capability.resolve, js_undefined(), values_array));
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    }
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    // 15. Return undefined.
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    return js_undefined();
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}
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PromiseAnyRejectElementFunction* PromiseAnyRejectElementFunction::create(GlobalObject& global_object, size_t index, PromiseValueList& errors, PromiseCapability capability, RemainingElements& remaining_elements)
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{
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    return global_object.heap().allocate<PromiseAnyRejectElementFunction>(global_object, index, errors, capability, remaining_elements, *global_object.function_prototype());
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}
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PromiseAnyRejectElementFunction::PromiseAnyRejectElementFunction(size_t index, PromiseValueList& errors, PromiseCapability capability, RemainingElements& remaining_elements, Object& prototype)
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    : PromiseResolvingElementFunction(index, errors, move(capability), remaining_elements, prototype)
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{
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}
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Value PromiseAnyRejectElementFunction::resolve_element()
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{
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    auto& vm = this->vm();
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    auto& global_object = this->global_object();
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    // 8. Set errors[index] to x.
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    m_values.values()[m_index] = vm.argument(0);
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    // 9. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
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    // 10. If remainingElementsCount.[[Value]] is 0, then
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    if (--m_remaining_elements.value == 0) {
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        // a. Let error be a newly created AggregateError object.
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        auto* error = AggregateError::create(global_object);
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        // b. Perform ! DefinePropertyOrThrow(error, "errors", PropertyDescriptor { [[Configurable]]: true, [[Enumerable]]: false, [[Writable]]: true, [[Value]]: ! CreateArrayFromList(errors) }).
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        auto errors_array = Array::create_from(global_object, m_values.values());
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        MUST(error->define_property_or_throw(vm.names.errors, { .value = errors_array, .writable = true, .enumerable = false, .configurable = true }));
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        // c. Return ? Call(promiseCapability.[[Reject]], undefined, « error »).
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        return TRY_OR_DISCARD(vm.call(*m_capability.reject, js_undefined(), error));
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    }
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    return js_undefined();
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}
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}
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