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			100 lines
		
	
	
	
		
			4.4 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			100 lines
		
	
	
	
		
			4.4 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| /*
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|  * Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
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|  *
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|  * SPDX-License-Identifier: BSD-2-Clause
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|  */
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| 
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| #include <LibJS/Runtime/AbstractOperations.h>
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| #include <LibJS/Runtime/Error.h>
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| #include <LibJS/Runtime/NativeFunction.h>
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| #include <LibJS/Runtime/PromiseCapability.h>
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| 
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| namespace JS {
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| 
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| NonnullGCPtr<PromiseCapability> PromiseCapability::create(VM& vm, GCPtr<Object> promise, GCPtr<FunctionObject> resolve, GCPtr<FunctionObject> reject)
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| {
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|     return vm.heap().allocate_without_realm<PromiseCapability>(promise, resolve, reject);
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| }
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| 
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| PromiseCapability::PromiseCapability(GCPtr<Object> promise, GCPtr<FunctionObject> resolve, GCPtr<FunctionObject> reject)
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|     : m_promise(promise)
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|     , m_resolve(resolve)
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|     , m_reject(reject)
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| {
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| }
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| 
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| void PromiseCapability::visit_edges(Cell::Visitor& visitor)
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| {
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|     visitor.visit(m_promise);
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|     visitor.visit(m_resolve);
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|     visitor.visit(m_reject);
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| }
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| 
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| // 27.2.1.5 NewPromiseCapability ( C ), https://tc39.es/ecma262/#sec-newpromisecapability
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| ThrowCompletionOr<NonnullGCPtr<PromiseCapability>> new_promise_capability(VM& vm, Value constructor)
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| {
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|     auto& realm = *vm.current_realm();
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| 
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|     // 1. If IsConstructor(C) is false, throw a TypeError exception.
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|     if (!constructor.is_constructor())
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|         return vm.throw_completion<TypeError>(ErrorType::NotAConstructor, TRY_OR_THROW_OOM(vm, constructor.to_string_without_side_effects()));
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| 
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|     // 2. NOTE: C is assumed to be a constructor function that supports the parameter conventions of the Promise constructor (see 27.2.3.1).
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| 
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|     // 3. Let promiseCapability be the PromiseCapability Record { [[Promise]]: undefined, [[Resolve]]: undefined, [[Reject]]: undefined }.
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|     auto promise_capability = PromiseCapability::create(vm, nullptr, nullptr, nullptr);
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| 
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|     // 4. Let executorClosure be a new Abstract Closure with parameters (resolve, reject) that captures promiseCapability and performs the following steps when called:
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|     // NOTE: Additionally to capturing the GC-allocated promise capability, we also create handles for
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|     // the resolve and reject values to keep them alive within the closure, as it may outlive the former.
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|     auto executor_closure = [&promise_capability, resolve_handle = make_handle({}), reject_handle = make_handle({})](auto& vm) mutable -> ThrowCompletionOr<Value> {
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|         auto resolve = vm.argument(0);
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|         auto reject = vm.argument(1);
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| 
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|         // No idea what other engines say here.
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|         // a. If promiseCapability.[[Resolve]] is not undefined, throw a TypeError exception.
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|         if (!resolve_handle.is_null())
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|             return vm.template throw_completion<TypeError>(ErrorType::GetCapabilitiesExecutorCalledMultipleTimes);
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| 
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|         // b. If promiseCapability.[[Reject]] is not undefined, throw a TypeError exception.
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|         if (!reject_handle.is_null())
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|             return vm.template throw_completion<TypeError>(ErrorType::GetCapabilitiesExecutorCalledMultipleTimes);
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| 
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|         // c. Set promiseCapability.[[Resolve]] to resolve.
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|         resolve_handle = make_handle(resolve);
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|         if (resolve.is_function())
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|             promise_capability->set_resolve(resolve.as_function());
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| 
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|         // d. Set promiseCapability.[[Reject]] to reject.
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|         reject_handle = make_handle(reject);
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|         if (reject.is_function())
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|             promise_capability->set_reject(reject.as_function());
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| 
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|         // e. Return undefined.
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|         return js_undefined();
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|     };
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| 
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|     // 5. Let executor be CreateBuiltinFunction(executorClosure, 2, "", « »).
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|     auto executor = NativeFunction::create(realm, move(executor_closure), 2, "");
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| 
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|     // 6. Let promise be ? Construct(C, « executor »).
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|     auto promise = TRY(construct(vm, constructor.as_function(), executor));
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| 
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|     // 7. If IsCallable(promiseCapability.[[Resolve]]) is false, throw a TypeError exception.
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|     // NOTE: We only assign a value in the executor closure if it is a function.
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|     if (promise_capability->resolve() == nullptr)
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|         return vm.throw_completion<TypeError>(ErrorType::NotAFunction, "Promise capability resolve value");
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| 
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|     // 8. If IsCallable(promiseCapability.[[Reject]]) is false, throw a TypeError exception.
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|     // NOTE: We only assign a value in the executor closure if it is a function.
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|     if (promise_capability->reject() == nullptr)
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|         return vm.throw_completion<TypeError>(ErrorType::NotAFunction, "Promise capability reject value");
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| 
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|     // 9. Set promiseCapability.[[Promise]] to promise.
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|     promise_capability->set_promise(*promise);
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| 
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|     // 10. Return promiseCapability.
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|     return promise_capability;
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| }
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| 
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| }
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