// Protocol Buffers - Google's data interchange format

// Copyright 2008 Google Inc.  All rights reserved.

//

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file or at

// https://developers.google.com/open-source/licenses/bsd

#ifndef GOOGLE_PROTOBUF_RAW_PTR_H__

#define GOOGLE_PROTOBUF_RAW_PTR_H__

#include <algorithm>

#include "absl/base/optimization.h"

// Must be included last.

#include "google/protobuf/port_def.inc"

namespace google {

namespace protobuf {

namespace internal {

PROTOBUF_EXPORT ABSL_CACHELINE_ALIGNED extern const char

    kZeroBuffer[std::max(ABSL_CACHELINE_SIZE, 64)];

// This class is trivially copyable/trivially destructible and constexpr

// constructible. The class allows for storing a raw pointer to a non-trivial

// object in a constexpr context.

template <typename T>

class RawPtr {

 public:

  constexpr RawPtr() : RawPtr(kZeroBuffer) {

    static_assert(sizeof(T) <= sizeof(kZeroBuffer), "");

    static_assert(alignof(T) <= ABSL_CACHELINE_SIZE, "");

  }

  explicit constexpr RawPtr(const void* p) : p_(const_cast<void*>(p)) {}

  bool IsDefault() const { return p_ == kZeroBuffer; }

  void DeleteIfNotDefault() {

    if (!IsDefault()) delete Get();

  }

  void ClearIfNotDefault() {

    if (!IsDefault()) Get()->Clear();

  }

  void Set(const void* p) { p_ = const_cast<void*>(p); }

  T* Get() const { return reinterpret_cast<T*>(p_); }

  T* operator->() const { return Get(); }

  T& operator*() const { return *Get(); }

 private:

  void* p_;

};

constexpr void* DefaultRawPtr() {

  return const_cast<void*>(static_cast<const void*>(kZeroBuffer));

}

}  // namespace internal

}  // namespace protobuf

}  // namespace google

#include "google/protobuf/port_undef.inc"

#endif  // GOOGLE_PROTOBUF_RAW_PTR_H__