| /* |
| * Copyright (C) 2009 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' |
| * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS |
| * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF |
| * THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #ifndef WeakGCPtr_h |
| #define WeakGCPtr_h |
| |
| #include "Collector.h" |
| #include <wtf/Noncopyable.h> |
| |
| namespace JSC { |
| |
| // A smart pointer whose get() function returns 0 for cells awaiting destruction. |
| template <typename T> class WeakGCPtr : Noncopyable { |
| public: |
| WeakGCPtr() : m_ptr(0) { } |
| WeakGCPtr(T* ptr) { assign(ptr); } |
| |
| T* get() const |
| { |
| if (!m_ptr || !Heap::isCellMarked(m_ptr)) |
| return 0; |
| return m_ptr; |
| } |
| |
| void clear(JSCell* ptr) |
| { |
| if (ptr == m_ptr) |
| m_ptr = 0; |
| } |
| |
| T& operator*() const { return *get(); } |
| T* operator->() const { return get(); } |
| |
| bool operator!() const { return !get(); } |
| |
| // This conversion operator allows implicit conversion to bool but not to other integer types. |
| #if COMPILER(WINSCW) |
| operator bool() const { return m_ptr; } |
| #else |
| typedef T* WeakGCPtr::*UnspecifiedBoolType; |
| operator UnspecifiedBoolType() const { return get() ? &WeakGCPtr::m_ptr : 0; } |
| #endif |
| |
| WeakGCPtr& operator=(T*); |
| |
| #if !ASSERT_DISABLED |
| bool hasDeadObject() const { return !!m_ptr; } |
| #endif |
| |
| private: |
| void assign(T* ptr) |
| { |
| if (ptr) |
| Heap::markCell(ptr); |
| m_ptr = ptr; |
| } |
| |
| T* m_ptr; |
| }; |
| |
| template <typename T> inline WeakGCPtr<T>& WeakGCPtr<T>::operator=(T* optr) |
| { |
| assign(optr); |
| return *this; |
| } |
| |
| template <typename T, typename U> inline bool operator==(const WeakGCPtr<T>& a, const WeakGCPtr<U>& b) |
| { |
| return a.get() == b.get(); |
| } |
| |
| template <typename T, typename U> inline bool operator==(const WeakGCPtr<T>& a, U* b) |
| { |
| return a.get() == b; |
| } |
| |
| template <typename T, typename U> inline bool operator==(T* a, const WeakGCPtr<U>& b) |
| { |
| return a == b.get(); |
| } |
| |
| template <typename T, typename U> inline bool operator!=(const WeakGCPtr<T>& a, const WeakGCPtr<U>& b) |
| { |
| return a.get() != b.get(); |
| } |
| |
| template <typename T, typename U> inline bool operator!=(const WeakGCPtr<T>& a, U* b) |
| { |
| return a.get() != b; |
| } |
| |
| template <typename T, typename U> inline bool operator!=(T* a, const WeakGCPtr<U>& b) |
| { |
| return a != b.get(); |
| } |
| |
| template <typename T, typename U> inline WeakGCPtr<T> static_pointer_cast(const WeakGCPtr<U>& p) |
| { |
| return WeakGCPtr<T>(static_cast<T*>(p.get())); |
| } |
| |
| template <typename T, typename U> inline WeakGCPtr<T> const_pointer_cast(const WeakGCPtr<U>& p) |
| { |
| return WeakGCPtr<T>(const_cast<T*>(p.get())); |
| } |
| |
| template <typename T> inline T* getPtr(const WeakGCPtr<T>& p) |
| { |
| return p.get(); |
| } |
| |
| } // namespace JSC |
| |
| #endif // WeakGCPtr_h |