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      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 "wtf/OwnPtr.h"
     33 #include "wtf/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 Type& 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
     64