NotifierTraits.h

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/*
 * Copyright Amazon.com, Inc. or its affiliates. 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.
 * A copy of the License is located at
 *
 *     http://aws.amazon.com/apache2.0/
 *
 * or in the "license" file accompanying this file. This file 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 ACSDK_NOTIFIER_INTERNAL_NOTIFIERTRAITS_H_
#define ACSDK_NOTIFIER_INTERNAL_NOTIFIERTRAITS_H_

#include <functional>
#include <memory>

namespace alexaClientSDK {
namespace notifier {

template <class T>
class NotifierTraits {
public:
    // This type is not constructable.
    NotifierTraits() noexcept = delete;
    ~NotifierTraits() noexcept = delete;
    void operator=(const NotifierTraits<T>&) noexcept = delete;

    static std::shared_ptr<void> toVoidPtr(const std::shared_ptr<T>& src) noexcept;

    static std::shared_ptr<T> fromVoidPtr(const std::shared_ptr<void>& src) noexcept;

    static std::function<void(const std::shared_ptr<void>&)> adaptFunction(
        std::function<void(const std::shared_ptr<T>&)>&& notify) noexcept;

private:
    static void invokeNotify(
        const std::function<void(const std::shared_ptr<T>&)>& notify,
        const std::shared_ptr<void>& data) noexcept;
};

template <class T>
std::shared_ptr<void> NotifierTraits<T>::toVoidPtr(const std::shared_ptr<T>& src) noexcept {
    return std::static_pointer_cast<void>(src);
}

template <class T>
std::shared_ptr<T> NotifierTraits<T>::fromVoidPtr(const std::shared_ptr<void>& src) noexcept {
    return std::static_pointer_cast<T>(src);
}

template <class T>
std::function<void(const std::shared_ptr<void>&)> NotifierTraits<T>::adaptFunction(
    std::function<void(const std::shared_ptr<T>&)>&& notify) noexcept {
    if (notify) {
        return std::bind(&NotifierTraits<T>::invokeNotify, std::move(notify), std::placeholders::_1);
    } else {
        return nullptr;
    }
}

template <class T>
void NotifierTraits<T>::invokeNotify(
    const std::function<void(const std::shared_ptr<T>&)>& notify,
    const std::shared_ptr<void>& data) noexcept {
    notify(fromVoidPtr(data));
}

}  // namespace notifier
}  // namespace alexaClientSDK

#endif  // ACSDK_NOTIFIER_INTERNAL_NOTIFIERTRAITS_H_