f418115f1b
Almost a year after first working on this, it's finally done: an implementation of Promises for LibJS! :^) The core functionality is working and closely following the spec [1]. I mostly took the pseudo code and transformed it into C++ - if you read and understand it, you will know how the spec implements Promises; and if you read the spec first, the code will look very familiar. Implemented functions are: - Promise() constructor - Promise.prototype.then() - Promise.prototype.catch() - Promise.prototype.finally() - Promise.resolve() - Promise.reject() For the tests I added a new function to test-js's global object, runQueuedPromiseJobs(), which calls vm.run_queued_promise_jobs(). By design, queued jobs normally only run after the script was fully executed, making it improssible to test handlers in individual test() calls by default [2]. Subsequent commits include integrations into LibWeb and js(1) - pretty-printing, running queued promise jobs when necessary. This has an unusual amount of dbgln() statements, all hidden behind the PROMISE_DEBUG flag - I'm leaving them in for now as they've been very useful while debugging this, things can get quite complex with so many asynchronously executed functions. I've not extensively explored use of these APIs for promise-based functionality in LibWeb (fetch(), Notification.requestPermission() etc.), but we'll get there in due time. [1]: https://tc39.es/ecma262/#sec-promise-objects [2]: https://tc39.es/ecma262/#sec-jobs-and-job-queues
66 lines
2.5 KiB
C++
66 lines
2.5 KiB
C++
/*
|
|
* Copyright (c) 2021, Linus Groh <mail@linusgroh.de>
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright notice, this
|
|
* list of conditions and the following disclaimer.
|
|
*
|
|
* 2. Redistributions in binary form must reproduce the above copyright notice,
|
|
* this list of conditions and the following disclaimer in the documentation
|
|
* and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
|
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
|
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
|
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <LibJS/Runtime/NativeFunction.h>
|
|
|
|
namespace JS {
|
|
|
|
struct AlreadyResolved final : public Cell {
|
|
bool value { false };
|
|
|
|
virtual const char* class_name() const override { return "AlreadyResolved"; }
|
|
|
|
protected:
|
|
// Allocated cells must be >= sizeof(FreelistEntry), which is 24 bytes -
|
|
// but AlreadyResolved is only 16 bytes without this.
|
|
u8 dummy[8];
|
|
};
|
|
|
|
class PromiseResolvingFunction final : public NativeFunction {
|
|
JS_OBJECT(PromiseResolvingFunction, NativeFunction);
|
|
|
|
public:
|
|
using FunctionType = AK::Function<Value(VM&, GlobalObject&, Promise&, AlreadyResolved&)>;
|
|
|
|
static PromiseResolvingFunction* create(GlobalObject&, Promise&, AlreadyResolved&, FunctionType);
|
|
|
|
explicit PromiseResolvingFunction(Promise&, AlreadyResolved&, FunctionType, Object& prototype);
|
|
virtual void initialize(GlobalObject&) override;
|
|
virtual ~PromiseResolvingFunction() override = default;
|
|
|
|
virtual Value call() override;
|
|
|
|
private:
|
|
virtual void visit_edges(Visitor&) override;
|
|
|
|
Promise& m_promise;
|
|
AlreadyResolved& m_already_resolved;
|
|
FunctionType m_native_function;
|
|
};
|
|
|
|
}
|