type_wrapper.hpp

来自「boost库提供标准的C++ API 配合dev c++使用,功能更加强大」· HPP 代码 · 共 55 行

#ifndef BOOST_MPL_AUX_TYPE_WRAPPER_HPP_INCLUDED
#define BOOST_MPL_AUX_TYPE_WRAPPER_HPP_INCLUDED

// + file: boost/mpl/aux_/type_wrapper.hpp
// + last modified: 09/may/03

// Copyright (c) 2000-03
// Peter Dimov, Aleksey Gurtovoy
//
// Permission to use, copy, modify, distribute and sell this software
// and its documentation for any purpose is hereby granted without fee, 
// provided that the above copyright notice appears in all copies and 
// that both the copyright notice and this permission notice appear in 
// supporting documentation. No representations are made about the 
// suitability of this software for any purpose. It is provided "as is" 
// without express or implied warranty.
//
// See http://www.boost.org/libs/mpl for documentation.

#include "boost/mpl/aux_/config/ctps.hpp"

namespace boost {
namespace mpl {
namespace aux {

template< typename T > struct type_wrapper
{
    typedef T type;
};

#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
// agurt 08/may/03: a complicated way to extract the wrapped type; need it 
// mostly for the sake of GCC (3.2.x), which ICEs if you try to extract the 
// nested 'type' from 'type_wrapper<T>' when the latter was the result of a
// 'typeof' expression
template< typename T > struct wrapped_type;

template< typename T > struct wrapped_type< type_wrapper<T> >
{
    typedef T type;
};
#else
template< typename W > struct wrapped_type
{
    typedef typename W::type type;
};
#endif

} // namespace aux
} // namespace mpl
} // namespace boost 

#endif // BOOST_MPL_AUX_TYPE_WRAPPER_HPP_INCLUDED