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
119 lines
2.8 KiB
C++
119 lines
2.8 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 <jsi/jsi.h>
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#include <type_traits>
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namespace facebook::react::bridging {
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// std::remove_cvref_t is not available until C++20.
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template <typename T>
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using remove_cvref_t = std::remove_cv_t<std::remove_reference_t<T>>;
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template <typename T>
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inline constexpr bool is_jsi_v =
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std::is_same_v<jsi::Value, remove_cvref_t<T>> ||
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std::is_same_v<jsi::String, remove_cvref_t<T>> ||
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std::is_base_of_v<jsi::Object, remove_cvref_t<T>>;
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template <typename T>
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struct ConverterBase {
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ConverterBase(jsi::Runtime &rt, T &&value)
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: rt_(rt), value_(std::forward<T>(value)) {}
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operator T() && {
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return std::forward<T>(this->value_);
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}
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protected:
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jsi::Runtime &rt_;
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T value_;
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};
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template <typename T>
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struct Converter : public ConverterBase<T> {
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using ConverterBase<T>::ConverterBase;
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};
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template <>
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struct Converter<jsi::Value> : public ConverterBase<jsi::Value> {
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using ConverterBase<jsi::Value>::ConverterBase;
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operator jsi::String() && {
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return std::move(value_).asString(rt_);
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}
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operator jsi::Object() && {
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return std::move(value_).asObject(rt_);
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}
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operator jsi::Array() && {
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return std::move(value_).asObject(rt_).asArray(rt_);
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}
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operator jsi::Function() && {
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return std::move(value_).asObject(rt_).asFunction(rt_);
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}
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};
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template <>
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struct Converter<jsi::Object> : public ConverterBase<jsi::Object> {
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using ConverterBase<jsi::Object>::ConverterBase;
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operator jsi::Array() && {
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return std::move(value_).asArray(rt_);
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}
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operator jsi::Function() && {
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return std::move(value_).asFunction(rt_);
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}
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};
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template <typename T>
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struct Converter<T &> {
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Converter(jsi::Runtime &rt, T &value) : rt_(rt), value_(value) {}
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operator T() && {
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// Copy the reference into a Value that then can be moved from.
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return Converter<jsi::Value>(rt_, jsi::Value(rt_, value_));
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}
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template <
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typename U,
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// Ensure the non-reference type can be converted to the desired type.
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std::enable_if_t<
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std::is_convertible_v<Converter<std::remove_cv_t<T>>, U>,
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int> = 0>
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operator U() && {
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return Converter<jsi::Value>(rt_, jsi::Value(rt_, value_));
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}
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private:
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jsi::Runtime &rt_;
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const T &value_;
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};
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template <typename T, std::enable_if_t<is_jsi_v<T>, int> = 0>
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auto convert(jsi::Runtime &rt, T &&value) {
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return Converter<T>(rt, std::forward<T>(value));
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}
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template <typename T, std::enable_if_t<std::is_scalar_v<T>, int> = 0>
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auto convert(jsi::Runtime &rt, T &&value) {
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return value;
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}
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template <typename T>
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auto convert(jsi::Runtime &rt, Converter<T> &&converter) {
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return std::move(converter);
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}
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} // namespace facebook::react::bridging
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