wtf/PtrAndFlags.h

   1 /*
   2  * Copyright (C) 2009 Google 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 are
   6  * met:
   7  *
   8  *     * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *     * Redistributions in binary form must reproduce the above
  11  * copyright notice, this list of conditions and the following disclaimer
  12  * in the documentation and/or other materials provided with the
  13  * distribution.
  14  *     * Neither the name of Google Inc. nor the names of its
  15  * contributors may be used to endorse or promote products derived from
  16  * this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 #ifndef PtrAndFlags_h
  32 #define PtrAndFlags_h
  33
  34 #include <wtf/Assertions.h>
  35
  36 namespace WTF {
  37     template<class T, typename FlagEnum> class PtrAndFlagsBase {
  38     public:
  39         bool isFlagSet(FlagEnum flagNumber) const { ASSERT(flagNumber < 2); return m_ptrAndFlags & (1 << flagNumber); }
  40         void setFlag(FlagEnum flagNumber) { ASSERT(flagNumber < 2); m_ptrAndFlags |= (1 << flagNumber);}
  41         void clearFlag(FlagEnum flagNumber) { ASSERT(flagNumber < 2); m_ptrAndFlags &= ~(1 << flagNumber);}
  42         T* get() const { return reinterpret_cast<T*>(m_ptrAndFlags & ~3); }
  43         void set(T* ptr)
  44         {
  45             ASSERT(!(reinterpret_cast<intptr_t>(ptr) & 3));
  46             m_ptrAndFlags = reinterpret_cast<intptr_t>(ptr) | (m_ptrAndFlags & 3);
  47 #ifndef NDEBUG
  48             m_leaksPtr = ptr;
  49 #endif
  50         }
  51
  52         bool operator!() const { return !get(); }
  53         T* operator->() const { return reinterpret_cast<T*>(m_ptrAndFlags & ~3); }
  54
  55     protected:
  56         intptr_t m_ptrAndFlags;
  57 #ifndef NDEBUG
  58         void* m_leaksPtr; // Only used to allow tools like leaks on OSX to detect that the memory is referenced.
  59 #endif
  60     };
  61
  62     template<class T, typename FlagEnum> class PtrAndFlags : public PtrAndFlagsBase<T, FlagEnum> {
  63     public:
  64         PtrAndFlags()
  65         {
  66             PtrAndFlagsBase<T, FlagEnum>::m_ptrAndFlags = 0;
  67         }
  68         PtrAndFlags(T* ptr)
  69         {
  70             PtrAndFlagsBase<T, FlagEnum>::m_ptrAndFlags = 0;
  71             PtrAndFlagsBase<T, FlagEnum>::set(ptr);
  72         }
  73     };
  74 } // namespace WTF
  75
  76 using WTF::PtrAndFlagsBase;
  77 using WTF::PtrAndFlags;
  78
  79 #endif // PtrAndFlags_h