| // Copyright 2016 PDFium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CORE_FXCRT_CFX_MAYBE_OWNED_H_ |
| #define CORE_FXCRT_CFX_MAYBE_OWNED_H_ |
| |
| #include <algorithm> |
| #include <memory> |
| #include <utility> |
| |
| #include "core/fxcrt/fx_memory.h" |
| #include "core/fxcrt/fx_system.h" |
| |
| // A template that can hold either owned or unowned references, and cleans up |
| // appropriately. Possibly the most pernicious anti-pattern imaginable, but |
| // it crops up throughout the codebase due to a desire to avoid copying-in |
| // objects or data. |
| template <typename T, typename D = std::default_delete<T>> |
| class CFX_MaybeOwned { |
| public: |
| CFX_MaybeOwned() : m_pObj(nullptr) {} |
| explicit CFX_MaybeOwned(T* ptr) : m_pObj(ptr) {} |
| explicit CFX_MaybeOwned(std::unique_ptr<T, D> ptr) |
| : m_pOwnedObj(std::move(ptr)), m_pObj(m_pOwnedObj.get()) {} |
| |
| CFX_MaybeOwned(const CFX_MaybeOwned& that) = delete; |
| CFX_MaybeOwned(CFX_MaybeOwned&& that) noexcept |
| : m_pOwnedObj(that.m_pOwnedObj.release()), m_pObj(that.m_pObj) { |
| that.m_pObj = nullptr; |
| } |
| |
| void Reset(std::unique_ptr<T, D> ptr) { |
| m_pOwnedObj = std::move(ptr); |
| m_pObj = m_pOwnedObj.get(); |
| } |
| void Reset(T* ptr = nullptr) { |
| m_pOwnedObj.reset(); |
| m_pObj = ptr; |
| } |
| |
| bool IsOwned() const { return !!m_pOwnedObj; } |
| T* Get() const { return m_pObj; } |
| std::unique_ptr<T, D> Release() { |
| ASSERT(IsOwned()); |
| return std::move(m_pOwnedObj); |
| } |
| |
| CFX_MaybeOwned& operator=(const CFX_MaybeOwned& that) = delete; |
| CFX_MaybeOwned& operator=(CFX_MaybeOwned&& that) { |
| m_pOwnedObj = std::move(that.m_pOwnedObj); |
| m_pObj = that.m_pObj; |
| that.m_pObj = nullptr; |
| return *this; |
| } |
| CFX_MaybeOwned& operator=(T* ptr) { |
| Reset(ptr); |
| return *this; |
| } |
| CFX_MaybeOwned& operator=(std::unique_ptr<T, D> ptr) { |
| Reset(std::move(ptr)); |
| return *this; |
| } |
| |
| bool operator==(const CFX_MaybeOwned& that) const { |
| return Get() == that.Get(); |
| } |
| bool operator==(const std::unique_ptr<T, D>& ptr) const { |
| return Get() == ptr.get(); |
| } |
| bool operator==(T* ptr) const { return Get() == ptr; } |
| |
| bool operator!=(const CFX_MaybeOwned& that) const { return !(*this == that); } |
| bool operator!=(const std::unique_ptr<T, D> ptr) const { |
| return !(*this == ptr); |
| } |
| bool operator!=(T* ptr) const { return !(*this == ptr); } |
| |
| explicit operator bool() const { return !!m_pObj; } |
| T& operator*() const { return *m_pObj; } |
| T* operator->() const { return m_pObj; } |
| |
| private: |
| std::unique_ptr<T, D> m_pOwnedObj; |
| T* m_pObj; |
| }; |
| |
| #endif // CORE_FXCRT_CFX_MAYBE_OWNED_H_ |