chromium/third_party/pdfium/core/fxcrt/retain_ptr.h

// Copyright 2016 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CORE_FXCRT_RETAIN_PTR_H_
#define CORE_FXCRT_RETAIN_PTR_H_

#include <stdint.h>

#include <functional>
#include <memory>
#include <type_traits>
#include <utility>

#include "core/fxcrt/check.h"
#include "core/fxcrt/compiler_specific.h"

namespace fxcrt {

// Used with std::unique_ptr to Release() objects that can't be deleted.
template <class T>
struct ReleaseDeleter { … };

// Analogous to base's scoped_refptr.
template <class T>
class TRIVIAL_ABI RetainPtr { … };

// Trivial implementation - internal ref count with virtual destructor.
class Retainable { … };

}  // namespace fxcrt

ReleaseDeleter;
Retainable;
RetainPtr;

namespace pdfium {

// Helper to make a RetainPtr along the lines of std::make_unique<>().
// Arguments are forwarded to T's constructor. Classes managed by RetainPtr
// should have protected (or private) constructors, and should friend this
// function.
template <typename T, typename... Args>
RetainPtr<T> MakeRetain(Args&&... args) { … }

// Type-deducing wrapper to make a RetainPtr from an ordinary pointer,
// since equivalent constructor is explicit.
template <typename T>
RetainPtr<T> WrapRetain(T* that) { … }

}  // namespace pdfium

// Macro to allow construction via MakeRetain<>() only, when used
// with a private constructor in a class.
#define CONSTRUCT_VIA_MAKE_RETAIN …

#endif  // CORE_FXCRT_RETAIN_PTR_H_