wtf/VectorTraits.h

   1 // -*- mode: c++; c-basic-offset: 4 -*-
   2 /*
   3  * This file is part of the KDE libraries
   4  * Copyright (C) 2006 Apple Computer, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Library General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Library General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Library General Public License
  17  * along with this library; see the file COPYING.LIB.  If not, write to
  18  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  19  * Boston, MA 02110-1301, USA.
  20  *
  21  */
  22
  23 #ifndef WTF_VectorTraits_h
  24 #define WTF_VectorTraits_h
  25
  26 #include "RefPtr.h"
  27 #include <utility>
  28
  29 using std::pair;
  30
  31 namespace WTF {
  32
  33     template <typename T> struct IsPod           { static const bool value = false; };
  34     template <> struct IsPod<bool>               { static const bool value = true; };
  35     template <> struct IsPod<char>               { static const bool value = true; };
  36     template <> struct IsPod<signed char>        { static const bool value = true; };
  37     template <> struct IsPod<unsigned char>      { static const bool value = true; };
  38     template <> struct IsPod<short>              { static const bool value = true; };
  39     template <> struct IsPod<unsigned short>     { static const bool value = true; };
  40     template <> struct IsPod<int>                { static const bool value = true; };
  41     template <> struct IsPod<unsigned int>       { static const bool value = true; };
  42     template <> struct IsPod<long>               { static const bool value = true; };
  43     template <> struct IsPod<unsigned long>      { static const bool value = true; };
  44     template <> struct IsPod<long long>          { static const bool value = true; };
  45     template <> struct IsPod<unsigned long long> { static const bool value = true; };
  46     template <> struct IsPod<float>              { static const bool value = true; };
  47     template <> struct IsPod<double>             { static const bool value = true; };
  48     template <> struct IsPod<long double>        { static const bool value = true; };
  49     template <typename P> struct IsPod<P *>      { static const bool value = true; };
  50
  51     template<bool isPod, typename T>
  52     class VectorTraitsBase;
  53
  54     template<typename T>
  55     struct VectorTraitsBase<false, T>
  56     {
  57         static const bool needsDestruction = true;
  58         static const bool needsInitialization = true;
  59         static const bool canInitializeWithMemset = false;
  60         static const bool canMoveWithMemcpy = false;
  61         static const bool canCopyWithMemcpy = false;
  62         static const bool canFillWithMemset = false;
  63         static const bool canCompareWithMemcmp = false;
  64     };
  65
  66     template<typename T>
  67     struct VectorTraitsBase<true, T>
  68     {
  69         static const bool needsDestruction = false;
  70         static const bool needsInitialization = false;
  71         static const bool canInitializeWithMemset = false;
  72         static const bool canMoveWithMemcpy = true;
  73         static const bool canCopyWithMemcpy = true;
  74         static const bool canFillWithMemset = sizeof(T) == sizeof(char);
  75         static const bool canCompareWithMemcmp = true;
  76     };
  77
  78     template<typename T>
  79     struct VectorTraits : VectorTraitsBase<IsPod<T>::value, T> { };
  80
  81     struct SimpleClassVectorTraits
  82     {
  83         static const bool needsDestruction = true;
  84         static const bool needsInitialization = true;
  85         static const bool canInitializeWithMemset = true;
  86         static const bool canMoveWithMemcpy = true;
  87         static const bool canCopyWithMemcpy = false;
  88         static const bool canFillWithMemset = false;
  89         static const bool canCompareWithMemcmp = true;
  90     };
  91
  92     // we know RefPtr is simple enough that initializing to 0 and moving with memcpy
  93     // (and then not destructing the original) will totally work
  94     template<typename P>
  95     struct VectorTraits<RefPtr<P> > : SimpleClassVectorTraits { };
  96
  97     template<typename First, typename Second>
  98     struct VectorTraits<pair<First, Second> >
  99     {
 100         typedef VectorTraits<First> FirstTraits;
 101         typedef VectorTraits<Second> SecondTraits;
 102
 103         static const bool needsDestruction = FirstTraits::needsDestruction || SecondTraits::needsDestruction;
 104         static const bool needsInitialization = FirstTraits::needsInitialization || SecondTraits::needsInitialization;
 105         static const bool canInitializeWithMemset = FirstTraits::canInitializeWithMemset && SecondTraits::canInitializeWithMemset;
 106         static const bool canMoveWithMemcpy = FirstTraits::canMoveWithMemcpy && SecondTraits::canMoveWithMemcpy;
 107         static const bool canCopyWithMemcpy = FirstTraits::canCopyWithMemcpy && SecondTraits::canCopyWithMemcpy;
 108         static const bool canFillWithMemset = false;
 109         static const bool canCompareWithMemcmp = FirstTraits::canCompareWithMemcmp && SecondTraits::canCompareWithMemcmp;
 110     };
 111
 112 } // namespace WTF
 113
 114 using WTF::VectorTraits;
 115 using WTF::SimpleClassVectorTraits;
 116
 117 #endif // WTF_VectorTraits_h