| 1 | /* |
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| 2 | * Copyright (C) 2009 Apple Inc. All Rights Reserved. |
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| 3 | * |
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| 4 | * Redistribution and use in source and binary forms, with or without |
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| 5 | * modification, are permitted provided that the following conditions |
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| 6 | * are met: |
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| 7 | * 1. Redistributions of source code must retain the above copyright |
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| 8 | * notice, this list of conditions and the following disclaimer. |
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| 9 | * 2. Redistributions in binary form must reproduce the above copyright |
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| 10 | * notice, this list of conditions and the following disclaimer in the |
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| 11 | * documentation and/or other materials provided with the distribution. |
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| 12 | * |
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| 13 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
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| 14 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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| 15 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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| 16 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
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| 17 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
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| 18 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
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| 19 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
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| 20 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
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| 21 | * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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| 22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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| 23 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 24 | */ |
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| 25 | |
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| 26 | #ifndef PossiblyNull_h |
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| 27 | #define PossiblyNull_h |
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| 28 | |
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| 29 | #include "Assertions.h" |
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| 30 | |
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| 31 | namespace WTF { |
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| 32 | |
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| 33 | template <typename T> struct PossiblyNull { |
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| 34 | PossiblyNull(T data) |
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| 35 | : m_data(data) |
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| 36 | { |
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| 37 | } |
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| 38 | PossiblyNull(const PossiblyNull<T>& source) |
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| 39 | : m_data(source.m_data) |
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| 40 | { |
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| 41 | source.m_data = 0; |
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| 42 | } |
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| 43 | ~PossiblyNull() { ASSERT(!m_data); } |
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| 44 | bool getValue(T& out) WARN_UNUSED_RETURN; |
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| 45 | private: |
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| 46 | mutable T m_data; |
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| 47 | }; |
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| 48 | |
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| 49 | template <typename T> bool PossiblyNull<T>::getValue(T& out) |
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| 50 | { |
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| 51 | out = m_data; |
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| 52 | bool result = !!m_data; |
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| 53 | m_data = 0; |
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| 54 | return result; |
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| 55 | } |
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| 56 | |
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| 57 | } |
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| 58 | |
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| 59 | #endif |
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| 60 | |
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