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LibJS: Implement async functions as generator functions in BC mode

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This applies a simple transformation, and adds a simple wrapper that
translates the generator interface to the async function interface.
This commit is contained in:
Ali Mohammad Pur 2021-11-11 00:46:07 +03:30 • committed by Linus Groh
parent c604e95993
commit 3b0bf05fa5
14 changed files with 192 additions and 43 deletions
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77
Userland/Libraries/LibJS/Runtime/AsyncFunctionDriverWrapper.cpp Normal file
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/*
* Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibJS/Runtime/AsyncFunctionDriverWrapper.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/NativeFunction.h>
#include <LibJS/Runtime/PromiseReaction.h>
#include <LibJS/Runtime/VM.h>
namespace JS {
ThrowCompletionOr<Value> AsyncFunctionDriverWrapper::create(GlobalObject& global_object, GeneratorObject* generator_object)
{
auto wrapper = global_object.heap().allocate<AsyncFunctionDriverWrapper>(global_object, global_object, generator_object);
return wrapper->react_to_async_task_completion(global_object.vm(), global_object, js_undefined(), true);
}
AsyncFunctionDriverWrapper::AsyncFunctionDriverWrapper(GlobalObject& global_object, GeneratorObject* generator_object)
: Promise(global_object)
, m_generator_object(generator_object)
, m_on_fulfillment(NativeFunction::create(global_object, "async.on_fulfillment"sv, [this](VM& vm, GlobalObject& global_object) {
return react_to_async_task_completion(vm, global_object, vm.argument(0), true);
}))
, m_on_rejection(NativeFunction::create(global_object, "async.on_rejection"sv, [this](VM& vm, GlobalObject& global_object) {
return react_to_async_task_completion(vm, global_object, vm.argument(0), false);
}))
{
}
ThrowCompletionOr<Value> AsyncFunctionDriverWrapper::react_to_async_task_completion(VM& vm, GlobalObject& global_object, Value value, bool is_successful)
{
auto generator_result = is_successful
? m_generator_object->next_impl(vm, global_object, value, {})
: m_generator_object->next_impl(vm, global_object, {}, value);
if (generator_result.is_throw_completion()) {
VERIFY(generator_result.throw_completion().type() == Completion::Type::Throw);
vm.clear_exception();
vm.stop_unwind();
auto promise = Promise::create(global_object);
promise->reject(generator_result.throw_completion().value());
return promise;
}
auto result = generator_result.release_value();
VERIFY(result.is_object());
auto promise_value = TRY(result.get(global_object, vm.names.value));
if (!promise_value.is_object() || !is<Promise>(promise_value.as_object())) {
auto promise = Promise::create(global_object);
promise->fulfill(promise_value);
return promise;
}
auto* promise = static_cast<Promise*>(&promise_value.as_object());
if (TRY(result.get(global_object, vm.names.done)).to_boolean())
return promise;
return promise->perform_then(m_on_fulfillment, m_on_rejection, PromiseCapability { promise, m_on_fulfillment, m_on_rejection });
}
AsyncFunctionDriverWrapper::~AsyncFunctionDriverWrapper()
{
}
void AsyncFunctionDriverWrapper::visit_edges(Cell::Visitor& visitor)
{
Base::visit_edges(visitor);
visitor.visit(m_generator_object);
visitor.visit(m_on_fulfillment);
visitor.visit(m_on_rejection);
}
}