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 <cstddef> 30#include <wtf/Noncopyable.h> 31 32namespace JSC { 33 34class WeakImpl; 35class WeakHandleOwner; 36 37// This is a free function rather than a Weak<T> member function so we can put it in Weak.cpp. 38JS_EXPORT_PRIVATE void weakClearSlowCase(WeakImpl*&); 39 40template<typename T> class Weak { 41 WTF_MAKE_NONCOPYABLE(Weak); 42public: 43 Weak() 44 : m_impl(0) 45 { 46 } 47 48 Weak(std::nullptr_t) 49 : m_impl(0) 50 { 51 } 52 53 Weak(T*, WeakHandleOwner* = 0, void* context = 0); 54 55 enum HashTableDeletedValueTag { HashTableDeletedValue }; 56 bool isHashTableDeletedValue() const; 57 Weak(HashTableDeletedValueTag); 58 59 Weak(Weak&&); 60 61 ~Weak() 62 { 63 clear(); 64 } 65 66 void swap(Weak&); 67 68 Weak& operator=(Weak&&); 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 WeakImpl* leakImpl() WARN_UNUSED_RETURN; 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