icl/detail/on_absorbtion.hpp

0001 /*-----------------------------------------------------------------------------+
0002 Copyright (c) 2010-2010: Joachim Faulhaber
0003 +------------------------------------------------------------------------------+
0004    Distributed under the Boost Software License, Version 1.0.
0005       (See accompanying file LICENCE.txt or copy at
0006            http://www.boost.org/LICENSE_1_0.txt)
0007 +-----------------------------------------------------------------------------*/
0008 #ifndef BOOST_ICL_TYPE_TRAITS_ON_ABSORBTION_HPP_JOFA_100915
0009 #define BOOST_ICL_TYPE_TRAITS_ON_ABSORBTION_HPP_JOFA_100915
0010
0011 namespace boost{ namespace icl
0012 {
0013
0014 template<class Type, class Combiner, bool absorbs_identities>
0015 struct on_absorbtion;
0016
0017 template<class Type, class Combiner>
0018 struct on_absorbtion<Type, Combiner, false>
0019 {
0020     typedef on_absorbtion type;
0021     typedef typename Type::codomain_type codomain_type;
0022
0023     static bool is_absorbable(const codomain_type&){ return false; }
0024 };
0025
0026 template<class Type, class Combiner>
0027 struct on_absorbtion<Type, Combiner, true>
0028 {
0029     typedef on_absorbtion type;
0030     typedef typename Type::codomain_type codomain_type;
0031     typedef typename Type::codomain_combine codomain_combine;
0032
0033     static bool is_absorbable(const codomain_type& co_value)
0034     {
0035         return co_value == Combiner::identity_element();
0036     }
0037 };
0038
0039 }} // namespace boost icl
0040
0041 #endif
0042
0043