1/* 2 * Copyright (C) 2009, 2012, 2013 Apple Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' 14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS 17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 23 * THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26#ifndef Weak_h 27#define Weak_h 28 29#include <wtf/Noncopyable.h> 30#include <wtf/NullPtr.h> 31 32namespace JSC { 33 34template<typename T> class PassWeak; 35class WeakImpl; 36class WeakHandleOwner; 37 38// This is a free function rather than a Weak<T> member function so we can put it in Weak.cpp. 39JS_EXPORT_PRIVATE void weakClearSlowCase(WeakImpl*&); 40 41template<typename T> class Weak { 42 WTF_MAKE_NONCOPYABLE(Weak); 43public: 44 Weak() 45 : m_impl(0) 46 { 47 } 48 49 explicit Weak(std::nullptr_t) 50 : m_impl(0) 51 { 52 } 53 54 explicit Weak(T*, WeakHandleOwner* = 0, void* context = 0); 55 56 enum HashTableDeletedValueTag { HashTableDeletedValue }; 57 bool isHashTableDeletedValue() const; 58 Weak(HashTableDeletedValueTag); 59 60 template<typename U> Weak(const PassWeak<U>&); 61 62 ~Weak() 63 { 64 clear(); 65 } 66 67 void swap(Weak&); 68 Weak& operator=(const PassWeak<T>&); 69 70 bool operator!() const; 71 T* operator->() const; 72 T& operator*() const; 73 T* get() const; 74 75 bool was(T*) const; 76 77 // This conversion operator allows implicit conversion to bool but not to other integer types. 78 typedef void* (Weak::*UnspecifiedBoolType); 79 operator UnspecifiedBoolType*() const; 80 81 PassWeak<T> release(); 82 void clear() 83 { 84 if (!m_impl) 85 return; 86 weakClearSlowCase(m_impl); 87 } 88 89private: 90 static WeakImpl* hashTableDeletedValue(); 91 92 WeakImpl* m_impl; 93}; 94 95} // namespace JSC 96 97#endif // Weak_h 98