cast.h
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// <cast.h> -*- C++ -*-
// Copyright (C) 2008-2025 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file ext/cast.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{ext/pointer.h}
*/
#ifndef _GLIBCXX_CAST_H
#define _GLIBCXX_CAST_H 1
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* These functions are here to allow containers to support non standard
* pointer types. For normal pointers, these resolve to the use of the
* standard cast operation. For other types the functions will perform
* the appropriate cast to/from the custom pointer class so long as that
* class meets the following conditions:
* 1) has a typedef element_type which names tehe type it points to.
* 2) has a get() const method which returns element_type*.
* 3) has a constructor which can take one element_type* argument.
*/
/**
* This type supports the semantics of the pointer cast operators (below.)
*/
template<typename _ToType>
struct _Caster
{ typedef typename _ToType::element_type* type; };
template<typename _ToType>
struct _Caster<_ToType*>
{ typedef _ToType* type; };
/**
* Casting operations for cases where _FromType is not a standard pointer.
* _ToType can be a standard or non-standard pointer. Given that _FromType
* is not a pointer, it must have a get() method that returns the standard
* pointer equivalent of the address it points to, and must have an
* element_type typedef which names the type it points to.
*/
template<typename _ToType, typename _FromType>
inline _ToType
__static_pointer_cast(const _FromType& __arg)
{ return _ToType(static_cast<typename _Caster<_ToType>::
type>(__arg.get())); }
template<typename _ToType, typename _FromType>
inline _ToType
__dynamic_pointer_cast(const _FromType& __arg)
{ return _ToType(dynamic_cast<typename _Caster<_ToType>::
type>(__arg.get())); }
template<typename _ToType, typename _FromType>
inline _ToType
__const_pointer_cast(const _FromType& __arg)
{ return _ToType(const_cast<typename _Caster<_ToType>::
type>(__arg.get())); }
template<typename _ToType, typename _FromType>
inline _ToType
__reinterpret_pointer_cast(const _FromType& __arg)
{ return _ToType(reinterpret_cast<typename _Caster<_ToType>::
type>(__arg.get())); }
/**
* Casting operations for cases where _FromType is a standard pointer.
* _ToType can be a standard or non-standard pointer.
*/
template<typename _ToType, typename _FromType>
inline _ToType
__static_pointer_cast(_FromType* __arg)
{ return _ToType(static_cast<typename _Caster<_ToType>::
type>(__arg)); }
template<typename _ToType, typename _FromType>
inline _ToType
__dynamic_pointer_cast(_FromType* __arg)
{ return _ToType(dynamic_cast<typename _Caster<_ToType>::
type>(__arg)); }
template<typename _ToType, typename _FromType>
inline _ToType
__const_pointer_cast(_FromType* __arg)
{ return _ToType(const_cast<typename _Caster<_ToType>::
type>(__arg)); }
template<typename _ToType, typename _FromType>
inline _ToType
__reinterpret_pointer_cast(_FromType* __arg)
{ return _ToType(reinterpret_cast<typename _Caster<_ToType>::
type>(__arg)); }
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // _GLIBCXX_CAST_H
__gnu_cxx
GNU extensions for public use.
__gnu_cxx::__static_pointer_cast
_ToType __static_pointer_cast(const _FromType &__arg)
Definition cast.h:68
__gnu_cxx::_Caster
Definition cast.h:53
__gnu_cxx::type