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       1             : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
       2             : /*
       3             :  * Version: MPL 1.1 / GPLv3+ / LGPLv3+
       4             :  *
       5             :  * The contents of this file are subject to the Mozilla Public License Version
       6             :  * 1.1 (the "License"); you may not use this file except in compliance with
       7             :  * the License or as specified alternatively below. You may obtain a copy of
       8             :  * the License at http://www.mozilla.org/MPL/
       9             :  *
      10             :  * Software distributed under the License is distributed on an "AS IS" basis,
      11             :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      12             :  * for the specific language governing rights and limitations under the
      13             :  * License.
      14             :  *
      15             :  * Major Contributor(s):
      16             :  * Copyright (C) 2010 Red Hat, Inc., David Tardon <dtardon@redhat.com>
      17             :  *  (initial developer)
      18             :  *
      19             :  * All Rights Reserved.
      20             :  *
      21             :  * For minor contributions see the git repository.
      22             :  *
      23             :  * Alternatively, the contents of this file may be used under the terms of
      24             :  * either the GNU General Public License Version 3 or later (the "GPLv3+"), or
      25             :  * the GNU Lesser General Public License Version 3 or later (the "LGPLv3+"),
      26             :  * in which case the provisions of the GPLv3+ or the LGPLv3+ are applicable
      27             :  * instead of those above.
      28             :  */
      29             : 
      30             : namespace detail
      31             : {
      32             : 
      33             : template<typename T>
      34             : struct has_clone
      35             : {
      36             :     template<typename U, U x>
      37             :     struct test;
      38             : 
      39             :     typedef char yes;
      40             :     typedef struct { char a[2]; } no;
      41             : 
      42             :     template<typename U>
      43             :     static yes& check_sig(U*, test<U* (U::*)() const, &U::clone>* = 0);
      44             :     template<typename U>
      45             :     static no& check_sig(...);
      46             : 
      47             :     enum
      48             :     {
      49             :         value = sizeof(check_sig<T>(0)) == sizeof(yes)
      50             :     };
      51             : };
      52             : 
      53             : template<typename T, bool HasClone>
      54             : struct cloner
      55             : {
      56         270 :     static T* clone(T* const other)
      57             :     {
      58         270 :         return new T(*other);
      59             :     }
      60             : };
      61             : 
      62             : template<typename T>
      63             : struct cloner<T, true>
      64             : {
      65         448 :     static T* clone(T* const other)
      66             :     {
      67         448 :         return other->clone();
      68             :     }
      69             : };
      70             : 
      71             : }
      72             : 
      73             : /** Creates a new copy of the passed object.
      74             :     If other is 0, just returns 0. Otherwise, if other has function
      75             :     named clone with signature T* (T::*)() const, the function is called.
      76             :     Otherwise, copy constructor is used.
      77             : 
      78             :     @returns 0 or newly allocated object
      79             :  */
      80             : template<typename T>
      81         718 : T* clone(T* const other)
      82             : {
      83         718 :     return other ? ::detail::cloner<T, ::detail::has_clone<T>::value>::clone(other) : 0;
      84             : }
      85             : 
      86             : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */