Chris@16: // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
Chris@16: // (C) Copyright 2003-2007 Jonathan Turkanis
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
Chris@16: 
Chris@16: // See http://www.boost.org/libs/iostreams for documentation.
Chris@16: 
Chris@16: // Contains the metafunction select, which mimics the effect of a chain of
Chris@16: // nested mpl if_'s.
Chris@16: //
Chris@16: // -----------------------------------------------------------------------------
Chris@16: //
Chris@16: // Usage:
Chris@16: //      
Chris@16: // typedef typename select<
Chris@16: //                      case1,  type1,
Chris@16: //                      case2,  type2,
Chris@16: //                      ...
Chris@16: //                      true_,  typen
Chris@16: //                  >::type selection;
Chris@16: //
Chris@16: // Here case1, case2, ... are models of MPL::IntegralConstant with value type
Chris@16: // bool, and n <= 12.
Chris@16: 
Chris@16: #ifndef BOOST_IOSTREAMS_SELECT_HPP_INCLUDED
Chris@16: #define BOOST_IOSTREAMS_SELECT_HPP_INCLUDED   
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1020)
Chris@16: # pragma once
Chris@16: #endif                  
Chris@16:  
Chris@16: #include <boost/type_traits/is_base_and_derived.hpp>
Chris@16: #include <boost/mpl/eval_if.hpp>
Chris@16: #include <boost/mpl/identity.hpp>
Chris@16: #include <boost/mpl/if.hpp>
Chris@16: #include <boost/mpl/void.hpp>
Chris@16: 
Chris@16: namespace boost { namespace iostreams { 
Chris@16: 
Chris@16: typedef mpl::true_ else_;
Chris@16: 
Chris@16: template< typename Case1 = mpl::true_,
Chris@16:           typename Type1 = mpl::void_,
Chris@16:           typename Case2 = mpl::true_,
Chris@16:           typename Type2 = mpl::void_,
Chris@16:           typename Case3 = mpl::true_,
Chris@16:           typename Type3 = mpl::void_,
Chris@16:           typename Case4 = mpl::true_,
Chris@16:           typename Type4 = mpl::void_,
Chris@16:           typename Case5 = mpl::true_,
Chris@16:           typename Type5 = mpl::void_,
Chris@16:           typename Case6 = mpl::true_,
Chris@16:           typename Type6 = mpl::void_,
Chris@16:           typename Case7 = mpl::true_,
Chris@16:           typename Type7 = mpl::void_,
Chris@16:           typename Case8 = mpl::true_,
Chris@16:           typename Type8 = mpl::void_,
Chris@16:           typename Case9 = mpl::true_,
Chris@16:           typename Type9 = mpl::void_,
Chris@16:           typename Case10 = mpl::true_,
Chris@16:           typename Type10 = mpl::void_,
Chris@16:           typename Case11 = mpl::true_,
Chris@16:           typename Type11 = mpl::void_,
Chris@16:           typename Case12 = mpl::true_,
Chris@16:           typename Type12 = mpl::void_ >
Chris@16: struct select {
Chris@16:     typedef typename
Chris@16:             mpl::eval_if<
Chris@16:                 Case1, mpl::identity<Type1>, mpl::eval_if<
Chris@16:                 Case2, mpl::identity<Type2>, mpl::eval_if<
Chris@16:                 Case3, mpl::identity<Type3>, mpl::eval_if<
Chris@16:                 Case4, mpl::identity<Type4>, mpl::eval_if<
Chris@16:                 Case5, mpl::identity<Type5>, mpl::eval_if<
Chris@16:                 Case6, mpl::identity<Type6>, mpl::eval_if<
Chris@16:                 Case7, mpl::identity<Type7>, mpl::eval_if<
Chris@16:                 Case8, mpl::identity<Type8>, mpl::eval_if<
Chris@16:                 Case9, mpl::identity<Type9>, mpl::eval_if<
Chris@16:                 Case10, mpl::identity<Type10>, mpl::eval_if<
Chris@16:                 Case11, mpl::identity<Type11>, mpl::if_<
Chris@16:                 Case12, Type12, mpl::void_ > > > > > > > > > > >
Chris@16:             >::type type;
Chris@16: };
Chris@16: 
Chris@16: } } // End namespaces iostreams, boost.
Chris@16: 
Chris@16: #endif // #ifndef BOOST_IOSTREAMS_SELECT_HPP_INCLUDED