--- /dev/null
+// <cast.h> -*- C++ -*-
+
+// Copyright (C) 2008 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 2, 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.
+
+// You should have received a copy of the GNU General Public License
+// along with this library; see the file COPYING. If not, write to
+// the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+// Boston, MA 02110-1301, USA.
+
+// As a special exception, you may use this file as part of a free software
+// library without restriction. Specifically, if other files instantiate
+// templates or use macros or inline functions from this file, or you compile
+// this file and link it with other files to produce an executable, this
+// file does not by itself cause the resulting executable to be covered by
+// the GNU General Public License. This exception does not however
+// invalidate any other reasons why the executable file might be covered by
+// the GNU General Public License.
+
+#ifndef _EXT_CAST_
+#define _EXT_CAST_ 1
+
+_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx);
+
+ /**
+ * 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 apprpriate 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
+
+#endif