New bridging API for JSI <-> C++

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

ReactCommon/react/bridging/Array.h

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <react/bridging/Base.h>
+
+#include <array>
+#include <deque>
+#include <initializer_list>
+#include <list>
+#include <tuple>
+#include <utility>
+#include <vector>
+
+namespace facebook::react {
+
+namespace array_detail {
+
+template <typename T, size_t N>
+struct BridgingStatic {
+  static jsi::Array toJs(
+      jsi::Runtime &rt,
+      const T &array,
+      const std::shared_ptr<CallInvoker> &jsInvoker) {
+    return toJs(rt, array, jsInvoker, std::make_index_sequence<N>{});
+  }
+
+ private:
+  template <size_t... Index>
+  static jsi::Array toJs(
+      facebook::jsi::Runtime &rt,
+      const T &array,
+      const std::shared_ptr<CallInvoker> &jsInvoker,
+      std::index_sequence<Index...>) {
+    return jsi::Array::createWithElements(
+        rt, bridging::toJs(rt, std::get<Index>(array), jsInvoker)...);
+  }
+};
+
+template <typename T>
+struct BridgingDynamic {
+  static jsi::Array toJs(
+      jsi::Runtime &rt,
+      const T &list,
+      const std::shared_ptr<CallInvoker> &jsInvoker) {
+    jsi::Array result(rt, list.size());
+    size_t index = 0;
+
+    for (const auto &item : list) {
+      result.setValueAtIndex(rt, index++, bridging::toJs(rt, item, jsInvoker));
+    }
+
+    return result;
+  }
+};
+
+} // namespace array_detail
+
+template <typename T, size_t N>
+struct Bridging<std::array<T, N>>
+    : array_detail::BridgingStatic<std::array<T, N>, N> {};
+
+template <typename T1, typename T2>
+struct Bridging<std::pair<T1, T2>>
+    : array_detail::BridgingStatic<std::pair<T1, T2>, 2> {};
+
+template <typename... Types>
+struct Bridging<std::tuple<Types...>>
+    : array_detail::BridgingStatic<std::tuple<Types...>, sizeof...(Types)> {};
+
+template <typename T>
+struct Bridging<std::deque<T>> : array_detail::BridgingDynamic<std::deque<T>> {
+};
+
+template <typename T>
+struct Bridging<std::initializer_list<T>>
+    : array_detail::BridgingDynamic<std::initializer_list<T>> {};
+
+template <typename T>
+struct Bridging<std::list<T>> : array_detail::BridgingDynamic<std::list<T>> {};
+
+template <typename T>
+struct Bridging<std::vector<T>>
+    : array_detail::BridgingDynamic<std::vector<T>> {
+  static std::vector<T> fromJs(
+      facebook::jsi::Runtime &rt,
+      const jsi::Array &array,
+      const std::shared_ptr<CallInvoker> &jsInvoker) {
+    size_t length = array.length(rt);
+
+    std::vector<T> vector;
+    vector.reserve(length);
+
+    for (size_t i = 0; i < length; i++) {
+      vector.push_back(
+          bridging::fromJs<T>(rt, array.getValueAtIndex(rt, i), jsInvoker));
+    }
+
+    return vector;
+  }
+};
+
+} // namespace facebook::react

ReactCommon/react/bridging/BUCK

@@ -1,12 +1,15 @@
-load("//tools/build_defs/oss:rn_defs.bzl", "ANDROID", "APPLE", "CXX", "react_native_xplat_shared_library_target", "react_native_xplat_target", "rn_xplat_cxx_library")
+load("//tools/build_defs/oss:rn_defs.bzl", "ANDROID", "APPLE", "CXX", "IOS", "MACOSX", "fb_xplat_cxx_test", "react_native_xplat_shared_library_target", "react_native_xplat_target", "rn_xplat_cxx_library")
 
 rn_xplat_cxx_library(
     name = "bridging",
     srcs = glob(["*.cpp"]),
     header_namespace = "react/bridging",
     exported_headers = glob(["*.h"]),
+    compiler_flags_enable_exceptions = True,
+    compiler_flags_enable_rtti = True,
     labels = ["supermodule:xplat/default/public.react_native.infra"],
     platforms = (ANDROID, APPLE, CXX),
+    tests = [":tests"],
     visibility = ["PUBLIC"],
     deps = [
         "//xplat/folly:headers_only",
@@ -17,3 +20,34 @@ rn_xplat_cxx_library(
         react_native_xplat_shared_library_target("jsi:jsi"),
     ],
 )
+
+rn_xplat_cxx_library(
+    name = "testlib",
+    header_namespace = "react/bridging",
+    exported_headers = glob(["tests/*.h"]),
+    platforms = (ANDROID, APPLE, CXX),
+    visibility = ["PUBLIC"],
+    exported_deps = [
+        "//xplat/third-party/gmock:gtest",
+    ],
+)
+
+fb_xplat_cxx_test(
+    name = "tests",
+    srcs = glob(["tests/*.cpp"]),
+    headers = glob(["tests/*.h"]),
+    apple_sdks = (IOS, MACOSX),
+    compiler_flags = [
+        "-fexceptions",
+        "-frtti",
+        "-std=c++17",
+        "-Wall",
+    ],
+    contacts = ["[email protected]"],
+    platforms = (ANDROID, APPLE, CXX),
+    deps = [
+        ":bridging",
+        "//xplat/hermes/API:HermesAPI",
+        "//xplat/third-party/gmock:gtest",
+    ],
+)

ReactCommon/react/bridging/Base.h

@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <react/bridging/Convert.h>
+
+#include <ReactCommon/CallInvoker.h>
+#include <folly/Function.h>
+#include <jsi/jsi.h>
+
+#include <cstdint>
+#include <memory>
+#include <type_traits>
+
+namespace facebook::react {
+
+template <typename T, typename = void>
+struct Bridging;
+
+template <>
+struct Bridging<void> {
+  // Highly generic code may result in "casting" to void.
+  static void fromJs(jsi::Runtime &, const jsi::Value &) {}
+};
+
+namespace bridging {
+namespace detail {
+
+template <typename F>
+struct function_wrapper;
+
+template <typename C, typename R, typename... Args>
+struct function_wrapper<R (C::*)(Args...)> {
+  using type = folly::Function<R(Args...)>;
+};
+
+template <typename C, typename R, typename... Args>
+struct function_wrapper<R (C::*)(Args...) const> {
+  using type = folly::Function<R(Args...)>;
+};
+
+template <typename T, typename = void>
+struct bridging_wrapper {
+  using type = remove_cvref_t<T>;
+};
+
+// Convert lambda types to move-only function types since we can't specialize
+// Bridging templates for arbitrary lambdas.
+template <typename T>
+struct bridging_wrapper<
+    T,
+    std::void_t<decltype(&remove_cvref_t<T>::operator())>>
+    : function_wrapper<decltype(&remove_cvref_t<T>::operator())> {};
+
+} // namespace detail
+
+template <typename T>
+using bridging_t = typename detail::bridging_wrapper<T>::type;
+
+template <typename R, typename T, std::enable_if_t<is_jsi_v<T>, int> = 0>
+auto fromJs(jsi::Runtime &rt, T &&value, const std::shared_ptr<CallInvoker> &)
+    -> decltype(static_cast<R>(convert(rt, std::forward<T>(value)))) {
+  return convert(rt, std::forward<T>(value));
+}
+
+template <typename R, typename T>
+auto fromJs(jsi::Runtime &rt, T &&value, const std::shared_ptr<CallInvoker> &)
+    -> decltype(Bridging<remove_cvref_t<R>>::fromJs(
+        rt,
+        convert(rt, std::forward<T>(value)))) {
+  return Bridging<remove_cvref_t<R>>::fromJs(
+      rt, convert(rt, std::forward<T>(value)));
+}
+
+template <typename R, typename T>
+auto fromJs(
+    jsi::Runtime &rt,
+    T &&value,
+    const std::shared_ptr<CallInvoker> &jsInvoker)
+    -> decltype(Bridging<remove_cvref_t<R>>::fromJs(
+        rt,
+        convert(rt, std::forward<T>(value)),
+        jsInvoker)) {
+  return Bridging<remove_cvref_t<R>>::fromJs(
+      rt, convert(rt, std::forward<T>(value)), jsInvoker);
+}
+
+template <typename T, std::enable_if_t<is_jsi_v<T>, int> = 0>
+auto toJs(
+    jsi::Runtime &rt,
+    T &&value,
+    const std::shared_ptr<CallInvoker> & = nullptr)
+    -> decltype(convert(rt, std::forward<T>(value))) {
+  return convert(rt, std::forward<T>(value));
+}
+
+template <typename T>
+auto toJs(
+    jsi::Runtime &rt,
+    T &&value,
+    const std::shared_ptr<CallInvoker> & = nullptr)
+    -> decltype(Bridging<bridging_t<T>>::toJs(rt, std::forward<T>(value))) {
+  return Bridging<bridging_t<T>>::toJs(rt, std::forward<T>(value));
+}
+
+template <typename T>
+auto toJs(
+    jsi::Runtime &rt,
+    T &&value,
+    const std::shared_ptr<CallInvoker> &jsInvoker)
+    -> decltype(Bridging<bridging_t<T>>::toJs(
+        rt,
+        std::forward<T>(value),
+        jsInvoker)) {
+  return Bridging<bridging_t<T>>::toJs(rt, std::forward<T>(value), jsInvoker);
+}
+
+} // namespace bridging
+} // namespace facebook::react

ReactCommon/react/bridging/Bool.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <react/bridging/Base.h>
+
+namespace facebook::react {
+
+template <>
+struct Bridging<bool> {
+  static bool fromJs(jsi::Runtime &rt, const jsi::Value &value) {
+    return value.asBool();
+  }
+
+  static jsi::Value toJs(jsi::Runtime &, bool value) {
+    return value;
+  }
+};
+
+} // namespace facebook::react

ReactCommon/react/bridging/Bridging.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <react/bridging/Array.h>
+#include <react/bridging/Bool.h>
+#include <react/bridging/Error.h>
+#include <react/bridging/Function.h>
+#include <react/bridging/Number.h>
+#include <react/bridging/Object.h>
+#include <react/bridging/Promise.h>
+#include <react/bridging/String.h>
+#include <react/bridging/Value.h>

ReactCommon/react/bridging/CallbackWrapper.h

@@ -84,6 +84,10 @@ class CallbackWrapper : public LongLivedObject {
     return *(jsInvoker_);
   }
 
+  std::shared_ptr<CallInvoker> jsInvokerPtr() {
+    return jsInvoker_;
+  }
+
   void allowRelease() override {
     if (auto longLivedObjectCollection = longLivedObjectCollection_.lock()) {
       if (longLivedObjectCollection != nullptr) {