1/* 2 * Copyright (C) 2014 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 CopyWriteBarrier_h 27#define CopyWriteBarrier_h 28 29#include "Heap.h" 30 31namespace JSC { 32 33template <typename T> 34class CopyWriteBarrier { 35public: 36 CopyWriteBarrier() 37 : m_value(0) 38 { 39 } 40 41 CopyWriteBarrier(VM& vm, const JSCell* owner, T& value) 42 { 43 this->set(vm, owner, &value); 44 } 45 46 CopyWriteBarrier(VM& vm, const JSCell* owner, T* value) 47 { 48 this->set(vm, owner, value); 49 } 50 51 bool operator!() const { return !m_value; } 52 53 typedef T* (CopyWriteBarrier::*UnspecifiedBoolType); 54 operator UnspecifiedBoolType*() const { return m_value ? reinterpret_cast<UnspecifiedBoolType*>(1) : 0; } 55 56 T* get() const 57 { 58 return m_value; 59 } 60 61 T* operator*() const 62 { 63 return get(); 64 } 65 66 T* operator->() const 67 { 68 return get(); 69 } 70 71 void set(VM& vm, const JSCell* owner, T* value) 72 { 73 this->m_value = value; 74 vm.heap.writeBarrier(owner); 75 } 76 77 void setWithoutWriteBarrier(T* value) 78 { 79 this->m_value = value; 80 } 81 82 void clear() { m_value = 0; } 83 84private: 85 T* m_value; 86}; 87 88} // namespace JSC 89 90#endif // CopyWriteBarrier_h 91