Move Source/WTF/wtf to Source/wtf

Source/WTF/wtf/PossiblyNull.h

-/*
- * 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. ``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
- * 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 PossiblyNull_h
-#define PossiblyNull_h
-
-#include <wtf/Assertions.h>
-
-namespace WTF {
-
-template <typename T> struct PossiblyNull {
-    PossiblyNull(T data)
-        : m_data(data)
-    {
-    }
-    PossiblyNull(const PossiblyNull<T>& source)
-        : m_data(source.m_data)
-    {
-        source.m_data = 0;
-    }
-    ~PossiblyNull() { ASSERT(!m_data); }
-    bool getValue(T& out) WARN_UNUSED_RETURN;
-private:
-    mutable T m_data;
-};
-
-template <typename T> bool PossiblyNull<T>::getValue(T& out)
-{
-    out = m_data;
-    bool result = !!m_data;
-    m_data = 0;
-    return result;
-}
-
-}
-
-#endif