Source/WTF/wtf/CheckedBoolean.h

/*
 * Copyright (C) 2011 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. 
 */

#pragma once

#include <wtf/Assertions.h>

class CheckedBoolean {
    WTF_MAKE_FAST_ALLOCATED;
public:
#if !ASSERT_DISABLED
    CheckedBoolean(const CheckedBoolean& other)
        : m_value(other.m_value)
        , m_checked(false)
    {
        other.m_checked = true;
    }
#endif

    CheckedBoolean(bool value)
        : m_value(value)
#if !ASSERT_DISABLED
        , m_checked(false)
#endif
    {
    }
    
    ~CheckedBoolean()
    {
        ASSERT(m_checked);
    }
    
    operator bool()
    {
#if !ASSERT_DISABLED
        m_checked = true;
#endif
        return m_value;
    }
    
private:
    bool m_value;
#if !ASSERT_DISABLED
    mutable bool m_checked;
#endif
};