smart_ptr/detail/sp_convertible.hpp

0001 #ifndef BOOST_SMART_PTR_DETAIL_SP_CONVERTIBLE_HPP_INCLUDED
0002 #define BOOST_SMART_PTR_DETAIL_SP_CONVERTIBLE_HPP_INCLUDED
0003
0004 // MS compatible compilers support #pragma once
0005
0006 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
0007 # pragma once
0008 #endif
0009
0010 //  detail/sp_convertible.hpp
0011 //
0012 //  Copyright 2008 Peter Dimov
0013 //
0014 //  Distributed under the Boost Software License, Version 1.0.
0015 //  See accompanying file LICENSE_1_0.txt or copy at
0016 //  http://www.boost.org/LICENSE_1_0.txt
0017
0018 #include <boost/config.hpp>
0019 #include <cstddef>
0020
0021 #if !defined( BOOST_SP_NO_SP_CONVERTIBLE ) && defined( BOOST_NO_SFINAE )
0022 # define BOOST_SP_NO_SP_CONVERTIBLE
0023 #endif
0024
0025 #if !defined( BOOST_SP_NO_SP_CONVERTIBLE ) && defined( __GNUC__ ) && ( __GNUC__ * 100 + __GNUC_MINOR__ < 303 )
0026 # define BOOST_SP_NO_SP_CONVERTIBLE
0027 #endif
0028
0029 #if !defined( BOOST_SP_NO_SP_CONVERTIBLE ) && defined( BOOST_BORLANDC ) && ( BOOST_BORLANDC < 0x630 )
0030 # define BOOST_SP_NO_SP_CONVERTIBLE
0031 #endif
0032
0033 #if !defined( BOOST_SP_NO_SP_CONVERTIBLE )
0034
0035 namespace boost
0036 {
0037
0038 namespace detail
0039 {
0040
0041 template< class Y, class T > struct sp_convertible
0042 {
0043     typedef char (&yes) [1];
0044     typedef char (&no)  [2];
0045
0046     static yes f( T* );
0047     static no  f( ... );
0048
0049     enum _vt { value = sizeof( (f)( static_cast<Y*>(0) ) ) == sizeof(yes) };
0050 };
0051
0052 template< class Y, class T > struct sp_convertible< Y, T[] >
0053 {
0054     enum _vt { value = false };
0055 };
0056
0057 template< class Y, class T > struct sp_convertible< Y[], T[] >
0058 {
0059     enum _vt { value = sp_convertible< Y[1], T[1] >::value };
0060 };
0061
0062 template< class Y, std::size_t N, class T > struct sp_convertible< Y[N], T[] >
0063 {
0064     enum _vt { value = sp_convertible< Y[1], T[1] >::value };
0065 };
0066
0067 struct sp_empty
0068 {
0069 };
0070
0071 template< bool > struct sp_enable_if_convertible_impl;
0072
0073 template<> struct sp_enable_if_convertible_impl<true>
0074 {
0075     typedef sp_empty type;
0076 };
0077
0078 template<> struct sp_enable_if_convertible_impl<false>
0079 {
0080 };
0081
0082 template< class Y, class T > struct sp_enable_if_convertible: public sp_enable_if_convertible_impl< sp_convertible< Y, T >::value >
0083 {
0084 };
0085
0086 } // namespace detail
0087
0088 } // namespace boost
0089
0090 #endif // !defined( BOOST_SP_NO_SP_CONVERTIBLE )
0091
0092 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_CONVERTIBLE_HPP_INCLUDED