1 // <cast.h> -*- C++ -*- 2 3 // Copyright (C) 2008, 2009 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 #ifndef _CAST_H 26 #define _CAST_H 1 27 28 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) 29 30 /** 31 * These functions are here to allow containers to support non standard 32 * pointer types. For normal pointers, these resolve to the use of the 33 * standard cast operation. For other types the functions will perform 34 * the apprpriate cast to/from the custom pointer class so long as that 35 * class meets the following conditions: 36 * 1) has a typedef element_type which names tehe type it points to. 37 * 2) has a get() const method which returns element_type*. 38 * 3) has a constructor which can take one element_type* argument. 39 */ 40 41 /** 42 * This type supports the semantics of the pointer cast operators (below.) 43 */ 44 template<typename _ToType> 45 struct _Caster 46 { typedef typename _ToType::element_type* type; }; 47 48 template<typename _ToType> 49 struct _Caster<_ToType*> 50 { typedef _ToType* type; }; 51 52 /** 53 * Casting operations for cases where _FromType is not a standard pointer. 54 * _ToType can be a standard or non-standard pointer. Given that _FromType 55 * is not a pointer, it must have a get() method that returns the standard 56 * pointer equivalent of the address it points to, and must have an 57 * element_type typedef which names the type it points to. 58 */ 59 template<typename _ToType, typename _FromType> 60 inline _ToType 61 __static_pointer_cast(const _FromType& __arg) 62 { return _ToType(static_cast<typename _Caster<_ToType>:: 63 type>(__arg.get())); } 64 65 template<typename _ToType, typename _FromType> 66 inline _ToType 67 __dynamic_pointer_cast(const _FromType& __arg) 68 { return _ToType(dynamic_cast<typename _Caster<_ToType>:: 69 type>(__arg.get())); } 70 71 template<typename _ToType, typename _FromType> 72 inline _ToType 73 __const_pointer_cast(const _FromType& __arg) 74 { return _ToType(const_cast<typename _Caster<_ToType>:: 75 type>(__arg.get())); } 76 77 template<typename _ToType, typename _FromType> 78 inline _ToType 79 __reinterpret_pointer_cast(const _FromType& __arg) 80 { return _ToType(reinterpret_cast<typename _Caster<_ToType>:: 81 type>(__arg.get())); } 82 83 /** 84 * Casting operations for cases where _FromType is a standard pointer. 85 * _ToType can be a standard or non-standard pointer. 86 */ 87 template<typename _ToType, typename _FromType> 88 inline _ToType 89 __static_pointer_cast(_FromType* __arg) 90 { return _ToType(static_cast<typename _Caster<_ToType>:: 91 type>(__arg)); } 92 93 template<typename _ToType, typename _FromType> 94 inline _ToType 95 __dynamic_pointer_cast(_FromType* __arg) 96 { return _ToType(dynamic_cast<typename _Caster<_ToType>:: 97 type>(__arg)); } 98 99 template<typename _ToType, typename _FromType> 100 inline _ToType 101 __const_pointer_cast(_FromType* __arg) 102 { return _ToType(const_cast<typename _Caster<_ToType>:: 103 type>(__arg)); } 104 105 template<typename _ToType, typename _FromType> 106 inline _ToType 107 __reinterpret_pointer_cast(_FromType* __arg) 108 { return _ToType(reinterpret_cast<typename _Caster<_ToType>:: 109 type>(__arg)); } 110 111 _GLIBCXX_END_NAMESPACE 112 113 #endif // _CAST_H 114