1 // <cast.h> -*- C++ -*- 2 3 // Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // 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 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file ext/cast.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{ext/pointer.h} 28 */ 29 30 #ifndef _GLIBCXX_CAST_H 31 #define _GLIBCXX_CAST_H 1 32 33 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 34 { 35 _GLIBCXX_BEGIN_NAMESPACE_VERSION 36 37 /** 38 * These functions are here to allow containers to support non standard 39 * pointer types. For normal pointers, these resolve to the use of the 40 * standard cast operation. For other types the functions will perform 41 * the apprpriate cast to/from the custom pointer class so long as that 42 * class meets the following conditions: 43 * 1) has a typedef element_type which names tehe type it points to. 44 * 2) has a get() const method which returns element_type*. 45 * 3) has a constructor which can take one element_type* argument. 46 */ 47 48 /** 49 * This type supports the semantics of the pointer cast operators (below.) 50 */ 51 template<typename _ToType> 52 struct _Caster 53 { typedef typename _ToType::element_type* type; }; 54 55 template<typename _ToType> 56 struct _Caster<_ToType*> 57 { typedef _ToType* type; }; 58 59 /** 60 * Casting operations for cases where _FromType is not a standard pointer. 61 * _ToType can be a standard or non-standard pointer. Given that _FromType 62 * is not a pointer, it must have a get() method that returns the standard 63 * pointer equivalent of the address it points to, and must have an 64 * element_type typedef which names the type it points to. 65 */ 66 template<typename _ToType, typename _FromType> 67 inline _ToType 68 __static_pointer_cast(const _FromType& __arg) 69 { return _ToType(static_cast<typename _Caster<_ToType>:: 70 type>(__arg.get())); } 71 72 template<typename _ToType, typename _FromType> 73 inline _ToType 74 __dynamic_pointer_cast(const _FromType& __arg) 75 { return _ToType(dynamic_cast<typename _Caster<_ToType>:: 76 type>(__arg.get())); } 77 78 template<typename _ToType, typename _FromType> 79 inline _ToType 80 __const_pointer_cast(const _FromType& __arg) 81 { return _ToType(const_cast<typename _Caster<_ToType>:: 82 type>(__arg.get())); } 83 84 template<typename _ToType, typename _FromType> 85 inline _ToType 86 __reinterpret_pointer_cast(const _FromType& __arg) 87 { return _ToType(reinterpret_cast<typename _Caster<_ToType>:: 88 type>(__arg.get())); } 89 90 /** 91 * Casting operations for cases where _FromType is a standard pointer. 92 * _ToType can be a standard or non-standard pointer. 93 */ 94 template<typename _ToType, typename _FromType> 95 inline _ToType 96 __static_pointer_cast(_FromType* __arg) 97 { return _ToType(static_cast<typename _Caster<_ToType>:: 98 type>(__arg)); } 99 100 template<typename _ToType, typename _FromType> 101 inline _ToType 102 __dynamic_pointer_cast(_FromType* __arg) 103 { return _ToType(dynamic_cast<typename _Caster<_ToType>:: 104 type>(__arg)); } 105 106 template<typename _ToType, typename _FromType> 107 inline _ToType 108 __const_pointer_cast(_FromType* __arg) 109 { return _ToType(const_cast<typename _Caster<_ToType>:: 110 type>(__arg)); } 111 112 template<typename _ToType, typename _FromType> 113 inline _ToType 114 __reinterpret_pointer_cast(_FromType* __arg) 115 { return _ToType(reinterpret_cast<typename _Caster<_ToType>:: 116 type>(__arg)); } 117 118 _GLIBCXX_END_NAMESPACE_VERSION 119 } // namespace 120 121 #endif // __GLIBCXX_CAST_H 122
