EVOLUTION-MANAGER
Edit File: minimum_category.hpp
// Copyright David Abrahams 2003. Use, modification and distribution is // subject to 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) #ifndef BOOST_ITERATOR_MINIMUM_CATEGORY_HPP_INCLUDED_ # define BOOST_ITERATOR_MINIMUM_CATEGORY_HPP_INCLUDED_ # include <boost/static_assert.hpp> # include <boost/type_traits/is_convertible.hpp> # include <boost/type_traits/is_same.hpp> # include <boost/mpl/placeholders.hpp> # include <boost/mpl/aux_/lambda_support.hpp> namespace boost { namespace iterators { namespace detail { template <bool GreaterEqual, bool LessEqual> struct minimum_category_impl; template <class T1, class T2> struct error_not_related_by_convertibility; template <> struct minimum_category_impl<true,false> { template <class T1, class T2> struct apply { typedef T2 type; }; }; template <> struct minimum_category_impl<false,true> { template <class T1, class T2> struct apply { typedef T1 type; }; }; template <> struct minimum_category_impl<true,true> { template <class T1, class T2> struct apply { BOOST_STATIC_ASSERT((is_same<T1,T2>::value)); typedef T1 type; }; }; template <> struct minimum_category_impl<false,false> { template <class T1, class T2> struct apply : error_not_related_by_convertibility<T1,T2> { }; }; } // namespace detail // // Returns the minimum category type or fails to compile // if T1 and T2 are unrelated. // template <class T1 = mpl::_1, class T2 = mpl::_2> struct minimum_category { typedef boost::iterators::detail::minimum_category_impl< ::boost::is_convertible<T1,T2>::value , ::boost::is_convertible<T2,T1>::value > outer; typedef typename outer::template apply<T1,T2> inner; typedef typename inner::type type; BOOST_MPL_AUX_LAMBDA_SUPPORT(2,minimum_category,(T1,T2)) }; template <> struct minimum_category<mpl::_1,mpl::_2> { template <class T1, class T2> struct apply : minimum_category<T1,T2> {}; BOOST_MPL_AUX_LAMBDA_SUPPORT_SPEC(2,minimum_category,(mpl::_1,mpl::_2)) }; } // namespace iterators } // namespace boost #endif // BOOST_ITERATOR_MINIMUM_CATEGORY_HPP_INCLUDED_