PointerCache.h

#pragma once

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2018 Filip Wasil and Fillwave community members
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <memory>
#include <array>
#include <utility>
#include <iostream>

namespace flw {

template <class TValueType>
class PointerCache {
 public:

  PointerCache()
    : mPtr(nullptr, [](TValueType*){})
    , mPtrStack() {
    // nothing
  }

  template <typename ...Args>
  PointerCache(Args&&... args)
    : mPtr(create(), [](TValueType*){}) {
    mPtrStack = TValueType(std::forward<Args>(args)...);
  }

  PointerCache(const PointerCache&) = delete;

  PointerCache(PointerCache&&) = delete;

  PointerCache& operator=(const PointerCache& ptr) = delete;

  PointerCache& operator=(PointerCache&&) = default;

  auto operator->() {
    return mPtr.operator->();
  }

 private:
  TValueType* create() {
    return &mPtrStack;
  }

  void reset() {
    mPtr.reset();
  }

  std::unique_ptr<TValueType, void(*)(TValueType*)> mPtr;
  TValueType mPtrStack;
};

} /* flw */