1 /* 2 * Copyright (C) 2009 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. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #ifndef PossiblyNull_h 27 #define PossiblyNull_h 28 29 #include "Assertions.h" 30 31 namespace WTF { 32 33 template <typename T> struct PossiblyNull { 34 PossiblyNull(T data) 35 : m_data(data) 36 { 37 } 38 PossiblyNull(const PossiblyNull<T>& source) 39 : m_data(source.m_data) 40 { 41 source.m_data = 0; 42 } 43 ~PossiblyNull() { ASSERT(!m_data); } 44 bool getValue(T& out) WARN_UNUSED_RETURN; 45 private: 46 mutable T m_data; 47 }; 48 49 template <typename T> bool PossiblyNull<T>::getValue(T& out) 50 { 51 out = m_data; 52 bool result = !!m_data; 53 m_data = 0; 54 return result; 55 } 56 57 } 58 59 #endif 60
