mirror of
https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Scott Kyle
30cb78e709
Summary: This adds `bridging::toJs` and `bridging::fromJs` functions that will safely cast to and from JSI values and C++ types. This is extensible by specializing `Bridging<T>` with `toJs` and/or `fromJs` static methods. There are specializations for most common C++ and JSI types along with tests for those. C++ functions and lambdas will effortlessly bridge into JS, and bridging JS functions back into C++ require you to choose `SyncCallback<R(Args...)>` or `AsyncCallback<Args...>` types. The sync version allows for having a return value and is strictly not movable to prevent accidentally moving onto another thread. The async version will move its args onto the JS thread and safely call the callback there, but hence always has a `void` return value. For promises, you can construct a `AsyncPromise<T>` that has `resolve` and `reject` methods that can be called from any thread, and will bridge into JS as a regular `Promise`. Changelog: [General][Added] - New bridging API for JSI <-> C++ Reviewed By: christophpurrer Differential Revision: D34607143 fbshipit-source-id: d832ac24cf84b4c1672a7b544d82e324d5fca3ef
103 lines
2.6 KiB
C++
103 lines
2.6 KiB
C++
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <react/bridging/Error.h>
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#include <react/bridging/Function.h>
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#include <react/bridging/LongLivedObject.h>
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#include <mutex>
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#include <optional>
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namespace facebook::react {
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template <typename T>
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class AsyncPromise {
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public:
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AsyncPromise(jsi::Runtime &rt, const std::shared_ptr<CallInvoker> &jsInvoker)
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: state_(std::make_shared<SharedState>()) {
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auto constructor = rt.global().getPropertyAsFunction(rt, "Promise");
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auto promise = constructor.callAsConstructor(
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rt,
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bridging::toJs(
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rt,
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// Safe to capture this since this is called synchronously.
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[this](AsyncCallback<T> resolve, AsyncCallback<Error> reject) {
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state_->resolve = std::move(resolve);
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state_->reject = std::move(reject);
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},
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jsInvoker));
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auto promiseHolder = std::make_shared<PromiseHolder>(promise.asObject(rt));
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LongLivedObjectCollection::get().add(promiseHolder);
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// The shared state can retain the promise holder weakly now.
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state_->promiseHolder = promiseHolder;
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}
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void resolve(T value) {
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std::lock_guard<std::mutex> lock(state_->mutex);
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if (state_->resolve) {
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state_->resolve->call(std::move(value));
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state_->resolve.reset();
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state_->reject.reset();
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}
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}
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void reject(Error error) {
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std::lock_guard<std::mutex> lock(state_->mutex);
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if (state_->reject) {
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state_->reject->call(std::move(error));
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state_->reject.reset();
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state_->resolve.reset();
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}
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}
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jsi::Object get(jsi::Runtime &rt) const {
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if (auto holder = state_->promiseHolder.lock()) {
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return jsi::Value(rt, holder->promise).asObject(rt);
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} else {
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throw jsi::JSError(rt, "Failed to get invalidated promise");
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}
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}
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private:
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struct PromiseHolder : LongLivedObject {
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PromiseHolder(jsi::Object p) : promise(std::move(p)) {}
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jsi::Object promise;
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};
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struct SharedState {
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~SharedState() {
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if (auto holder = promiseHolder.lock()) {
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holder->allowRelease();
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}
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}
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std::mutex mutex;
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std::weak_ptr<PromiseHolder> promiseHolder;
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std::optional<AsyncCallback<T>> resolve;
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std::optional<AsyncCallback<Error>> reject;
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};
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std::shared_ptr<SharedState> state_;
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};
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template <typename T>
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struct Bridging<AsyncPromise<T>> {
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static jsi::Object toJs(jsi::Runtime &rt, const AsyncPromise<T> &promise) {
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return promise.get(rt);
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}
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};
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} // namespace facebook::react
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