1/* 2 * Copyright (C) 2006, 2007, 2009, 2010 Apple Inc. All rights reserved. 3 * 4 * This library is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU Library General Public 6 * License as published by the Free Software Foundation; either 7 * version 2 of the License, or (at your option) any later version. 8 * 9 * This library is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * Library General Public License for more details. 13 * 14 * You should have received a copy of the GNU Library General Public License 15 * along with this library; see the file COPYING.LIB. If not, write to 16 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 17 * Boston, MA 02110-1301, USA. 18 * 19 */ 20 21#ifndef TreeShared_h 22#define TreeShared_h 23 24#include <wtf/Assertions.h> 25#include <wtf/Noncopyable.h> 26#include <wtf/Threading.h> 27 28namespace WebCore { 29 30#ifndef NDEBUG 31template<typename T> class TreeShared; 32template<typename T> void adopted(TreeShared<T>*); 33#endif 34 35template<typename T> class TreeShared { 36 WTF_MAKE_NONCOPYABLE(TreeShared); 37public: 38 TreeShared() 39 : m_refCount(1) 40 , m_parent(0) 41#ifndef NDEBUG 42 , m_adoptionIsRequired(true) 43#endif 44 { 45 ASSERT(isMainThread()); 46#ifndef NDEBUG 47 m_deletionHasBegun = false; 48 m_inRemovedLastRefFunction = false; 49#endif 50 } 51 virtual ~TreeShared() 52 { 53 ASSERT(isMainThread()); 54 ASSERT(!m_refCount); 55 ASSERT(m_deletionHasBegun); 56 ASSERT(!m_adoptionIsRequired); 57 } 58 59 void ref() 60 { 61 ASSERT(isMainThread()); 62 ASSERT(!m_deletionHasBegun); 63 ASSERT(!m_inRemovedLastRefFunction); 64 ASSERT(!m_adoptionIsRequired); 65 ++m_refCount; 66 } 67 68 void deref() 69 { 70 ASSERT(isMainThread()); 71 ASSERT(m_refCount >= 0); 72 ASSERT(!m_deletionHasBegun); 73 ASSERT(!m_inRemovedLastRefFunction); 74 ASSERT(!m_adoptionIsRequired); 75 if (--m_refCount <= 0 && !m_parent) { 76#ifndef NDEBUG 77 m_inRemovedLastRefFunction = true; 78#endif 79 removedLastRef(); 80 } 81 } 82 83 bool hasOneRef() const 84 { 85 ASSERT(!m_deletionHasBegun); 86 ASSERT(!m_inRemovedLastRefFunction); 87 return m_refCount == 1; 88 } 89 90 int refCount() const 91 { 92 return m_refCount; 93 } 94 95 void setParent(T* parent) 96 { 97 ASSERT(isMainThread()); 98 m_parent = parent; 99 } 100 101 T* parent() const 102 { 103 ASSERT(isMainThread()); 104 return m_parent; 105 } 106 107#ifndef NDEBUG 108 bool m_deletionHasBegun; 109 bool m_inRemovedLastRefFunction; 110#endif 111 112protected: 113 virtual void removedLastRef() 114 { 115#ifndef NDEBUG 116 m_deletionHasBegun = true; 117#endif 118 delete this; 119 } 120 121private: 122#ifndef NDEBUG 123 friend void adopted<>(TreeShared<T>*); 124#endif 125 126 int m_refCount; 127 T* m_parent; 128#ifndef NDEBUG 129 bool m_adoptionIsRequired; 130#endif 131}; 132 133#ifndef NDEBUG 134 135template<typename T> inline void adopted(TreeShared<T>* object) 136{ 137 if (!object) 138 return; 139 ASSERT(!object->m_deletionHasBegun); 140 ASSERT(!object->m_inRemovedLastRefFunction); 141 object->m_adoptionIsRequired = false; 142} 143 144#endif 145 146} 147 148#endif // TreeShared.h 149