1// <cast.h> -*- C++ -*-
2
3// Copyright (C) 2008-2013 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
33namespace __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