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309 lines
8.3 KiB
309 lines
8.3 KiB
/* /////////////////////////////////////////////////////////////////////////
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* File: stlsoft/conversion/ptr_cast.hpp
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*
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* Purpose: A cast that throws bad_cast for dynamic pointer casting, as well
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* as references.
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*
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* Created: 28th December 2002
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* Updated: 10th August 2009
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*
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* Home: http://stlsoft.org/
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*
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* Copyright (c) 2002-2009, Matthew Wilson and Synesis Software
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* - Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* - Neither the name(s) of Matthew Wilson and Synesis Software nor the names of
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* any contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* ////////////////////////////////////////////////////////////////////// */
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/** \file stlsoft/conversion/ptr_cast.hpp
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*
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* \brief [C++ only] Definition of the stlsoft::ptr_cast cast class
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* (\ref group__library__conversion "Conversion" Library).
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*/
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#ifndef STLSOFT_INCL_STLSOFT_CONVERSION_HPP_PTR_CAST
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#define STLSOFT_INCL_STLSOFT_CONVERSION_HPP_PTR_CAST
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#ifndef STLSOFT_DOCUMENTATION_SKIP_SECTION
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# define STLSOFT_VER_STLSOFT_CONVERSION_HPP_PTR_CAST_MAJOR 4
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# define STLSOFT_VER_STLSOFT_CONVERSION_HPP_PTR_CAST_MINOR 0
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# define STLSOFT_VER_STLSOFT_CONVERSION_HPP_PTR_CAST_REVISION 8
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# define STLSOFT_VER_STLSOFT_CONVERSION_HPP_PTR_CAST_EDIT 38
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#endif /* !STLSOFT_DOCUMENTATION_SKIP_SECTION */
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/* /////////////////////////////////////////////////////////////////////////
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* Compatibility
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*/
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/*
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[Incompatibilies-start]
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STLSOFT_COMPILER_IS_INTEL: _MSC_VER<1310
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STLSOFT_COMPILER_IS_MSVC: _MSC_VER<1310
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STLSOFT_COMPILER_IS_WATCOM:
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[Incompatibilies-end]
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*/
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/* /////////////////////////////////////////////////////////////////////////
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* Includes
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*/
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#ifndef STLSOFT_INCL_STLSOFT_H_STLSOFT
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# include <stlsoft/stlsoft.h>
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#endif /* !STLSOFT_INCL_STLSOFT_H_STLSOFT */
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#ifndef STLSOFT_INCL_STLSOFT_META_HPP_BASE_TYPE_TRAITS
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# include <stlsoft/meta/base_type_traits.hpp>
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#endif /* !STLSOFT_INCL_STLSOFT_META_HPP_BASE_TYPE_TRAITS */
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#ifndef STLSOFT_INCL_TYPEINFO
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# define STLSOFT_INCL_TYPEINFO
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# include <typeinfo>
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#endif /* !STLSOFT_INCL_TYPEINFO */
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/* /////////////////////////////////////////////////////////////////////////
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* Namespace
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*/
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#ifndef _STLSOFT_NO_NAMESPACE
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namespace stlsoft
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{
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#endif /* _STLSOFT_NO_NAMESPACE */
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/* /////////////////////////////////////////////////////////////////////////
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* Classes
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*/
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/** \brief A cast that throws bad_cast for pointer cast failures, as well as
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* for reference casts.
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*
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* \ingroup group__library__conversion
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*
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* Assume the following class hierarchy, and variables:
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\code
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class Parent
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{
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public:
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virtual ~Parent();
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};
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class A
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: public Parent
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{
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public:
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~A();
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};
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class B
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: public Parent
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{
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public:
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~B();
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};
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. . .
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A a;
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B b;
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\endcode
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*
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* The following code segments illustrate the similarities and differences
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* between dynamic_cast and ptr_cast:
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*
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* (i) dynamic cast of reference that succeeds
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\code
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A &ra1 = dynamic_cast<A&>(a);
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A &ra2 = stlsoft::ptr_cast<A&>(a);
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assert(&ra1 == &ra2);
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\endcode
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*
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* (ii) dynamic cast of pointer that succeeds
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\code
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A *pa = dynamic_cast<A*>(&a);
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assert(NULL != pa);
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assert(stlsoft::ptr_cast<A*>(&a) == pa);
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\endcode
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*
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* (iii) dynamic cast of reference that fails
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\code
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bool bCastFailed1 = false;
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try
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{
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B &b1 = dynamic_cast<B&>(a);
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. . . // Will never get here
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}
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catch(std::bad_cast &)
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{
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bCastFailed1 = true;
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}
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assert(bCastFailed1);
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bool bCastFailed2 = false;
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try
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{
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B &rb = stlsoft::ptr_cast<B&>(a);
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. . . // Will never get here
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}
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catch(std::bad_cast &)
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{
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bCastFailed2 = true;
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}
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assert(bCastFailed2);
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\endcode
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*
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* (iv) dynamic cast of pointer that fails
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\code
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assert(NULL == dynamic_cast<B*>(&a));
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bool bCastFailed = false;
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try
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{
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B &rb = stlsoft::ptr_cast<B&>(&a);
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. . . // Will never get here
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}
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catch(std::bad_cast &)
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{
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bCastFailed = true;
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}
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assert(bCastFailed);
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\endcode
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*
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* \note This is described in detail in chapter 19 of
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* <a href = "http://www.imperfectcplusplus.com/">Imperfect C++</a>.
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*/
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template <ss_typename_param_k Target>
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struct ptr_cast
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{
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public:
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/// The target type
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typedef Target target_type;
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/// The current instantiation of the type
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typedef ptr_cast<Target> class_type;
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/// The target base type
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typedef ss_typename_type_k stlsoft::base_type_traits<Target>::cv_type target_base_type;
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/// The reference type
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typedef target_base_type& reference_type;
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/// The pointer type
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typedef target_base_type* pointer_type;
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private:
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typedef ss_typename_type_k stlsoft::base_type_traits<Target>::base_type target_base_type_;
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static target_base_type_* manage_const(target_base_type_* p)
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{
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return p;
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}
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#if defined(STLSOFT_COMPILER_IS_BORLAND)
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static target_base_type_* manage_const(target_base_type_ const* p)
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{
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return const_cast<target_base_type_*>(p);
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}
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#else /* ? compiler */
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static target_base_type_ const* manage_const(target_base_type_ const* p)
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{
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return p;
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}
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#endif /* compiler */
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public:
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/// Constructor used when casting a reference
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template <ss_typename_param_k Source>
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ptr_cast(Source &s)
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: m_p(manage_const(&dynamic_cast<Target>(s)))
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{
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// Nothing to do: dynamic_cast throws for reference types
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}
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/// Constructor used when casting a pointer
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template <ss_typename_param_k Source>
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#if defined(STLSOFT_COMPILER_IS_BORLAND) || \
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defined(STLSOFT_COMPILER_IS_GCC) || \
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defined(STLSOFT_COMPILER_IS_MWERKS)
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ptr_cast(Source*& s)
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#else /* ? compiler */
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ptr_cast(Source* s)
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#endif /* compiler */
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: m_p(manage_const(dynamic_cast<Target>(s)))
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{
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if(NULL == m_p)
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{
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STLSOFT_THROW_X(stlsoft_ns_qual_std(bad_cast)());
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}
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}
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#ifndef STLSOFT_DOCUMENTATION_SKIP_SECTION
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ptr_cast(pointer_type pt)
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: m_p(pt)
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{}
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ptr_cast(reference_type t)
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: m_p(&t)
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{}
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#endif /* !STLSOFT_DOCUMENTATION_SKIP_SECTION */
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public:
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/// Converts an instance of the cast class to a reference
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operator reference_type () const
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{
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return const_cast<reference_type>(*m_p);
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}
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/// Converts an instance of the cast class to a pointer
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operator pointer_type () const
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{
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return const_cast<pointer_type>(m_p);
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}
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private:
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pointer_type m_p;
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// Not to be implemented
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private:
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ptr_cast(class_type const&);
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};
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////////////////////////////////////////////////////////////////////////////
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// Unit-testing
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#ifdef STLSOFT_UNITTEST
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# include "./unittest/ptr_cast_unittest_.h"
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#endif /* STLSOFT_UNITTEST */
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/* ////////////////////////////////////////////////////////////////////// */
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#ifndef _STLSOFT_NO_NAMESPACE
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} // namespace stlsoft
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#endif /* _STLSOFT_NO_NAMESPACE */
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/* ////////////////////////////////////////////////////////////////////// */
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#endif /* !STLSOFT_INCL_STLSOFT_CONVERSION_HPP_PTR_CAST */
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/* ///////////////////////////// end of file //////////////////////////// */
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