1 // Copyright 2016 PDFium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com 6 7 #ifndef CORE_FXCRT_CFX_WEAK_PTR_H_ 8 #define CORE_FXCRT_CFX_WEAK_PTR_H_ 9 10 #include <cstddef> 11 #include <memory> 12 #include <utility> 13 14 #include "core/fxcrt/cfx_retain_ptr.h" 15 #include "core/fxcrt/fx_system.h" 16 17 template <class T, class D = std::default_delete<T>> 18 class CFX_WeakPtr { 19 public: 20 CFX_WeakPtr() {} 21 CFX_WeakPtr(const CFX_WeakPtr& that) : m_pHandle(that.m_pHandle) {} 22 CFX_WeakPtr(CFX_WeakPtr&& that) { Swap(that); } 23 explicit CFX_WeakPtr(std::unique_ptr<T, D> pObj) 24 : m_pHandle(new Handle(std::move(pObj))) {} 25 26 // Deliberately implicit to allow passing nullptr. 27 // NOLINTNEXTLINE(runtime/explicit) 28 CFX_WeakPtr(std::nullptr_t arg) {} 29 30 explicit operator bool() const { return m_pHandle && !!m_pHandle->Get(); } 31 bool HasOneRef() const { return m_pHandle && m_pHandle->HasOneRef(); } 32 T* operator->() { return m_pHandle->Get(); } 33 const T* operator->() const { return m_pHandle->Get(); } 34 CFX_WeakPtr& operator=(const CFX_WeakPtr& that) { 35 m_pHandle = that.m_pHandle; 36 return *this; 37 } 38 bool operator==(const CFX_WeakPtr& that) const { 39 return m_pHandle == that.m_pHandle; 40 } 41 bool operator!=(const CFX_WeakPtr& that) const { return !(*this == that); } 42 43 T* Get() const { return m_pHandle ? m_pHandle->Get() : nullptr; } 44 void DeleteObject() { 45 if (m_pHandle) { 46 m_pHandle->Clear(); 47 m_pHandle.Reset(); 48 } 49 } 50 void Reset() { m_pHandle.Reset(); } 51 void Reset(std::unique_ptr<T, D> pObj) { 52 m_pHandle.Reset(new Handle(std::move(pObj))); 53 } 54 void Swap(CFX_WeakPtr& that) { m_pHandle.Swap(that.m_pHandle); } 55 56 private: 57 class Handle { 58 public: 59 explicit Handle(std::unique_ptr<T, D> ptr) 60 : m_nCount(0), m_pObj(std::move(ptr)) {} 61 void Reset(std::unique_ptr<T, D> ptr) { m_pObj = std::move(ptr); } 62 void Clear() { // Now you're all weak ptrs ... 63 m_pObj.reset(); // unique_ptr nulls first before invoking delete. 64 } 65 T* Get() const { return m_pObj.get(); } 66 T* Retain() { 67 ++m_nCount; 68 return m_pObj.get(); 69 } 70 void Release() { 71 if (--m_nCount == 0) 72 delete this; 73 } 74 bool HasOneRef() const { return m_nCount == 1; } 75 76 private: 77 ~Handle() {} 78 79 intptr_t m_nCount; 80 std::unique_ptr<T, D> m_pObj; 81 }; 82 83 CFX_RetainPtr<Handle> m_pHandle; 84 }; 85 86 #endif // CORE_FXCRT_CFX_WEAK_PTR_H_ 87