aosp12/external/google-fruit/include/fruit/component_function.h

74 lines
2.7 KiB
C++

/*
* Copyright 2014 Google Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef FRUIT_COMPONENT_FUNCTION_H
#define FRUIT_COMPONENT_FUNCTION_H
#include <fruit/impl/fruit_internal_forward_decls.h>
namespace fruit {
/**
* See fruit::componentFunction() helper for how to construct a ComponentFunction, and see
* PartialComponent::installComponentFunctions() for more information on using ComponentFunction objects.
*/
template <typename ComponentType, typename... ComponentFunctionArgs>
class ComponentFunction {
private:
ComponentType (*getComponent)(ComponentFunctionArgs...);
std::tuple<ComponentFunctionArgs...> args_tuple;
/**
* This is (intentionally) private, use fruit::componentFunction() to construct ComponentFunction objects.
*/
explicit ComponentFunction(ComponentType (*getComponent)(ComponentFunctionArgs...), ComponentFunctionArgs... args);
friend struct fruit::impl::ComponentStorageEntry;
public:
// Prefer using the simpler componentFunction() below instead of this.
template <typename... ActualArgs>
static ComponentFunction<ComponentType, ComponentFunctionArgs...> create(
ComponentType (*getComponent)(ComponentFunctionArgs...), ActualArgs&&... args);
ComponentFunction(const ComponentFunction&) = default;
ComponentFunction(ComponentFunction&&) noexcept = default;
ComponentFunction& operator=(const ComponentFunction&) = default;
ComponentFunction& operator=(ComponentFunction&& other) noexcept {
args_tuple = std::move(other.args_tuple);
return *this;
}
ComponentType operator()();
};
/**
* This function allows to easily construct a ComponentFunction without explicitly mentioning its type.
* See PartialComponent::installComponentFunctions() for more information on using ComponentFunction.
*/
template <typename... ComponentParams, typename... FormalArgs, typename... ActualArgs>
ComponentFunction<fruit::Component<ComponentParams...>, FormalArgs...> componentFunction(
fruit::Component<ComponentParams...> (*getComponent)(FormalArgs...),
ActualArgs&&... args);
}
#include <fruit/impl/component_function.defn.h>
#endif // FRUIT_COMPONENT_FUNCTION_H