sl@0: // (C) Copyright Jonathan Turkanis 2003.
sl@0: // Distributed under the Boost Software License, Version 1.0. (See accompanying
sl@0: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
sl@0: 
sl@0: // See http://www.boost.org/libs/iostreams for documentation.
sl@0: 
sl@0: // Contains the metafunction select, which mimics the effect of a chain of
sl@0: // nested mpl if_'s.
sl@0: //
sl@0: // -----------------------------------------------------------------------------
sl@0: //
sl@0: // Usage:
sl@0: //      
sl@0: // typedef typename select<
sl@0: //                      case1,  type1,
sl@0: //                      case2,  type2,
sl@0: //                      ...
sl@0: //                      true_,  typen
sl@0: //                  >::type selection;
sl@0: //
sl@0: // Here case1, case2, ... are models of MPL::IntegralConstant with value type
sl@0: // bool, and n <= 10.
sl@0: 
sl@0: #ifndef BOOST_IOSTREAMS_SELECT_HPP_INCLUDED
sl@0: #define BOOST_IOSTREAMS_SELECT_HPP_INCLUDED   
sl@0: 
sl@0: #if defined(_MSC_VER) && (_MSC_VER >= 1020)
sl@0: # pragma once
sl@0: #endif                  
sl@0:  
sl@0: #include <boost/type_traits/is_base_and_derived.hpp>
sl@0: #include <boost/mpl/eval_if.hpp>
sl@0: #include <boost/mpl/identity.hpp>
sl@0: #include <boost/mpl/if.hpp>
sl@0: #include <boost/mpl/void.hpp>
sl@0: 
sl@0: namespace boost { namespace iostreams { 
sl@0: 
sl@0: typedef mpl::true_ else_;
sl@0: 
sl@0: template< typename Case1 = mpl::true_,
sl@0:           typename Type1 = mpl::void_,
sl@0:           typename Case2 = mpl::true_,
sl@0:           typename Type2 = mpl::void_,
sl@0:           typename Case3 = mpl::true_,
sl@0:           typename Type3 = mpl::void_,
sl@0:           typename Case4 = mpl::true_,
sl@0:           typename Type4 = mpl::void_,
sl@0:           typename Case5 = mpl::true_,
sl@0:           typename Type5 = mpl::void_,
sl@0:           typename Case6 = mpl::true_,
sl@0:           typename Type6 = mpl::void_,
sl@0:           typename Case7 = mpl::true_,
sl@0:           typename Type7 = mpl::void_,
sl@0:           typename Case8 = mpl::true_,
sl@0:           typename Type8 = mpl::void_,
sl@0:           typename Case9 = mpl::true_,
sl@0:           typename Type9 = mpl::void_,
sl@0:           typename Case10 = mpl::true_,
sl@0:           typename Type10 = mpl::void_ >
sl@0: struct select {
sl@0:     typedef typename
sl@0:             mpl::eval_if<
sl@0:                 Case1, mpl::identity<Type1>, mpl::eval_if<
sl@0:                 Case2, mpl::identity<Type2>, mpl::eval_if<
sl@0:                 Case3, mpl::identity<Type3>, mpl::eval_if<
sl@0:                 Case4, mpl::identity<Type4>, mpl::eval_if<
sl@0:                 Case5, mpl::identity<Type5>, mpl::eval_if<
sl@0:                 Case6, mpl::identity<Type6>, mpl::eval_if<
sl@0:                 Case7, mpl::identity<Type7>, mpl::eval_if<
sl@0:                 Case8, mpl::identity<Type8>, mpl::eval_if<
sl@0:                 Case9, mpl::identity<Type9>, mpl::if_<
sl@0:                 Case10, Type10, mpl::void_ > > > > > > > > >
sl@0:             >::type type;
sl@0: };
sl@0: 
sl@0: } } // End namespaces iostreams, boost.
sl@0: 
sl@0: #endif // #ifndef BOOST_IOSTREAMS_SELECT_HPP_INCLUDED