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