1 /*

     2  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.

     3  *

     4  * This library is free software; you can redistribute it and/or

     5  * modify it under the terms of the GNU Library General Public

     6  * License as published by the Free Software Foundation; either

     7  * version 2 of the License, or (at your option) any later version.

     8  *

     9  * This library is distributed in the hope that it will be useful,

    10  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    12  * Library General Public License for more details.

    13  *

    14  * You should have received a copy of the GNU Library General Public License

    15  * along with this library; see the file COPYING.LIB.  If not, write to

    16  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

    17  * Boston, MA 02110-1301, USA.

    18  *

    19  */

    20 

    21 #ifndef WTF_VectorTraits_h

    22 #define WTF_VectorTraits_h

    23 

    24 #include "OwnPtr.h"

    25 #include "RefPtr.h"

    26 #include "TypeTraits.h"

    27 #include <utility>

    28 #include <memory>

    29 

    30 using std::pair;

    31 

    32 namespace WTF {

    33 

    34     template<bool isPod, typename T>

    35     struct VectorTraitsBase;

    36 

    37     template<typename T>

    38     struct VectorTraitsBase<false, T>

    39     {

    40         static const bool needsDestruction = true;

    41         static const bool needsInitialization = true;

    42         static const bool canInitializeWithMemset = false;

    43         static const bool canMoveWithMemcpy = false;

    44         static const bool canCopyWithMemcpy = false;

    45         static const bool canFillWithMemset = false;

    46         static const bool canCompareWithMemcmp = false;

    47     };

    48 

    49     template<typename T>

    50     struct VectorTraitsBase<true, T>

    51     {

    52         static const bool needsDestruction = false;

    53         static const bool needsInitialization = false;

    54         static const bool canInitializeWithMemset = false;

    55         static const bool canMoveWithMemcpy = true;

    56         static const bool canCopyWithMemcpy = true;

    57         static const bool canFillWithMemset = sizeof(T) == sizeof(char);

    58         static const bool canCompareWithMemcmp = true;

    59     };

    60 

    61     template<typename T>

    62     struct VectorTraits : VectorTraitsBase<IsPod<T>::value, T> { };

    63 

    64     struct SimpleClassVectorTraits

    65     {

    66         static const bool needsDestruction = true;

    67         static const bool needsInitialization = true;

    68         static const bool canInitializeWithMemset = true;

    69         static const bool canMoveWithMemcpy = true;

    70         static const bool canCopyWithMemcpy = false;

    71         static const bool canFillWithMemset = false;

    72         static const bool canCompareWithMemcmp = true;

    73     };

    74 

    75     // we know OwnPtr and RefPtr are simple enough that initializing to 0 and moving with memcpy

    76     // (and then not destructing the original) will totally work

    77     template<typename P>

    78     struct VectorTraits<RefPtr<P> > : SimpleClassVectorTraits { };

    79 

    80     template<typename P>

    81     struct VectorTraits<OwnPtr<P> > : SimpleClassVectorTraits { };

    82 

    83     template<typename First, typename Second>

    84     struct VectorTraits<pair<First, Second> >

    85     {

    86         typedef VectorTraits<First> FirstTraits;

    87         typedef VectorTraits<Second> SecondTraits;

    88 

    89         static const bool needsDestruction = FirstTraits::needsDestruction || SecondTraits::needsDestruction;

    90         static const bool needsInitialization = FirstTraits::needsInitialization || SecondTraits::needsInitialization;

    91         static const bool canInitializeWithMemset = FirstTraits::canInitializeWithMemset && SecondTraits::canInitializeWithMemset;

    92         static const bool canMoveWithMemcpy = FirstTraits::canMoveWithMemcpy && SecondTraits::canMoveWithMemcpy;

    93         static const bool canCopyWithMemcpy = FirstTraits::canCopyWithMemcpy && SecondTraits::canCopyWithMemcpy;

    94         static const bool canFillWithMemset = false;

    95         static const bool canCompareWithMemcmp = FirstTraits::canCompareWithMemcmp && SecondTraits::canCompareWithMemcmp;

    96     };

    97 

    98 } // namespace WTF

    99 

   100 using WTF::VectorTraits;

   101 using WTF::SimpleClassVectorTraits;

   102 

   103 #endif // WTF_VectorTraits_h