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