wtf/PassTraits.h

   1 /*
   2  * Copyright (C) 2011 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  *
   8  * 1.  Redistributions of source code must retain the above copyright
   9  *     notice, this list of conditions and the following disclaimer.
  10  * 2.  Redistributions in binary form must reproduce the above copyright
  11  *     notice, this list of conditions and the following disclaimer in the
  12  *     documentation and/or other materials provided with the distribution.
  13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  14  *     its contributors may be used to endorse or promote products derived
  15  *     from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 #ifndef WTF_PassTraits_h
  30 #define WTF_PassTraits_h
  31
  32 #include "OwnPtr.h"
  33 #include "RefPtr.h"
  34
  35 // The PassTraits template exists to help optimize (or make possible) use
  36 // of WTF data structures with WTF smart pointers that have a Pass
  37 // variant for transfer of ownership
  38
  39 namespace WTF {
  40
  41 template<typename T> struct PassTraits {
  42     typedef T Type;
  43     typedef T PassType;
  44     static PassType transfer(Type& value) { return value; }
  45 };
  46
  47 template<typename T> struct PassTraits<OwnPtr<T> > {
  48     typedef OwnPtr<T> Type;
  49     typedef PassOwnPtr<T> PassType;
  50     static PassType transfer(Type& value) { return value.release(); }
  51 };
  52
  53 template<typename T> struct PassTraits<RefPtr<T> > {
  54     typedef RefPtr<T> Type;
  55     typedef PassRefPtr<T> PassType;
  56     static PassType transfer(Type& value) { return value.release(); }
  57 };
  58
  59 } // namespace WTF
  60
  61 using WTF::PassTraits;
  62
  63 #endif // WTF_PassTraits_h