runtime/StructureTransitionTable.h

   1 /*
   2  * Copyright (C) 2008, 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 COMPUTER, 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 COMPUTER, 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 StructureTransitionTable_h
  27 #define StructureTransitionTable_h
  28
  29 #include "UString.h"
  30 #include <wtf/HashFunctions.h>
  31 #include <wtf/HashMap.h>
  32 #include <wtf/HashTraits.h>
  33 #include <wtf/OwnPtr.h>
  34 #include <wtf/RefPtr.h>
  35
  36 namespace JSC {
  37
  38     class Structure;
  39
  40     struct StructureTransitionTableHash {
  41         typedef std::pair<RefPtr<UString::Rep>, unsigned> Key;
  42         static unsigned hash(const Key& p)
  43         {
  44             return p.first->existingHash();
  45         }
  46
  47         static bool equal(const Key& a, const Key& b)
  48         {
  49             return a == b;
  50         }
  51
  52         static const bool safeToCompareToEmptyOrDeleted = true;
  53     };
  54
  55     struct StructureTransitionTableHashTraits {
  56         typedef WTF::HashTraits<RefPtr<UString::Rep> > FirstTraits;
  57         typedef WTF::GenericHashTraits<unsigned> SecondTraits;
  58         typedef std::pair<FirstTraits::TraitType, SecondTraits::TraitType > TraitType;
  59
  60         static const bool emptyValueIsZero = FirstTraits::emptyValueIsZero && SecondTraits::emptyValueIsZero;
  61         static TraitType emptyValue() { return std::make_pair(FirstTraits::emptyValue(), SecondTraits::emptyValue()); }
  62
  63         static const bool needsDestruction = FirstTraits::needsDestruction || SecondTraits::needsDestruction;
  64
  65         static void constructDeletedValue(TraitType& slot) { FirstTraits::constructDeletedValue(slot.first); }
  66         static bool isDeletedValue(const TraitType& value) { return FirstTraits::isDeletedValue(value.first); }
  67     };
  68
  69 } // namespace JSC
  70
  71 #endif // StructureTransitionTable_h