111 lines
3.1 KiB
C++
111 lines
3.1 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 <memory>
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#include <mutex>
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#include <optional>
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#include <shared_mutex>
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#include <string>
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#include <unordered_map>
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#include <react/debug/flags.h>
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#include <react/debug/react_native_assert.h>
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namespace facebook::react {
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/*
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* General purpose dependency injection container.
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* Instance types must be copyable.
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*/
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class ContextContainer final {
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public:
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using Shared = std::shared_ptr<const ContextContainer>;
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/*
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* Registers an instance of the particular type `T` in the container
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* using the provided `key`. Only one instance can be registered per key.
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* The method does nothing if given `key` already exists in the container.
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*
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* Convention is to use the plain base class name for the key, so for
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* example if the type `T` is `std::shared_ptr<const ReactNativeConfig>`,
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* then one would use `"ReactNativeConfig"` for the `key`, even if the
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* instance is actually a `shared_ptr` of derived class
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*`ReactNativeConfig`.
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*/
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template <typename T>
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void insert(const std::string& key, const T& instance) const {
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std::unique_lock lock(mutex_);
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instances_.insert({key, std::make_shared<T>(instance)});
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}
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/*
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* Removes an instance stored for a given `key`.
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* Does nothing if the instance was not found.
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*/
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void erase(const std::string& key) const {
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std::unique_lock lock(mutex_);
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instances_.erase(key);
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}
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/*
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* Updates the container with values from a given container.
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* Values with keys that already exist in the container will be replaced with
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* values from the given container.
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*/
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void update(const ContextContainer& contextContainer) const {
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std::unique_lock lock(mutex_);
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for (const auto& pair : contextContainer.instances_) {
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instances_.erase(pair.first);
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instances_.insert(pair);
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}
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}
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/*
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* Returns a previously registered instance of the particular type `T`
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* for `key`.
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* Throws an exception if the instance could not be found.
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*/
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template <typename T>
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T at(const std::string& key) const {
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std::shared_lock lock(mutex_);
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react_native_assert(
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instances_.find(key) != instances_.end() &&
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"ContextContainer doesn't have an instance for given key.");
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return *static_cast<T*>(instances_.at(key).get());
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}
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/*
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* Returns a (wrapped in an optional) previously registered instance of
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* the particular type `T` for given `key`.
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* Returns an empty optional if the instance could not be found.
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*/
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template <typename T>
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std::optional<T> find(const std::string& key) const {
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std::shared_lock lock(mutex_);
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auto iterator = instances_.find(key);
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if (iterator == instances_.end()) {
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return {};
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}
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return *static_cast<T*>(iterator->second.get());
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}
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private:
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mutable std::shared_mutex mutex_;
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// Protected by mutex_`.
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mutable std::unordered_map<std::string, std::shared_ptr<void>> instances_;
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};
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} // namespace facebook::react
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