Chris@16: // Copyright (C) 2013 Eurodecision
Chris@16: // Authors: Guillaume Pinot
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: // See http://www.boost.org/libs/property_map for documentation.
Chris@16: 
Chris@16: #ifndef BOOST_PROPERTY_MAP_COMPOSE_PROPERTY_MAP_HPP
Chris@16: #define BOOST_PROPERTY_MAP_COMPOSE_PROPERTY_MAP_HPP
Chris@16: 
Chris@16: #include <boost/property_map/property_map.hpp>
Chris@16: #include <boost/type_traits.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: // A compose property map: make_compose_property_map(f, g)[x] == f[g[x]]
Chris@16: //
Chris@16: // g must be a readable property map.
Chris@16: // The category of compose_property_map(f, g) is the category of f.
Chris@16: 
Chris@16: template <typename FPMap, typename GPMap>
Chris@16: class compose_property_map
Chris@16: {
Chris@16: public:
Chris@16:     typedef typename boost::property_traits<FPMap>::category category;
Chris@16:     typedef typename boost::property_traits<GPMap>::key_type key_type; 
Chris@16:     typedef typename boost::property_traits<FPMap>::value_type value_type;
Chris@16:     typedef typename boost::property_traits<FPMap>::reference reference;
Chris@16: 
Chris@16:     inline compose_property_map(const FPMap &f_p, const GPMap &g_p):
Chris@16:         f(f_p), g(g_p)
Chris@16:     {}
Chris@16: 
Chris@16:     inline compose_property_map() {}
Chris@16: 
Chris@16:     inline reference
Chris@16:     operator[](const key_type &v) const {
Chris@16:         return f[get(g, v)];
Chris@16:     }
Chris@16: 
Chris@16:     // return type of get():
Chris@16:     // if (reference is not a ref)
Chris@16:     //     value_type
Chris@16:     // else if (reference is const)
Chris@16:     //     reference
Chris@16:     // else
Chris@16:     //     const value_type&
Chris@16:     inline friend typename boost::mpl::if_<
Chris@16:         boost::mpl::not_< boost::is_reference<reference> >,
Chris@16:         value_type,
Chris@16:         typename boost::mpl::if_<
Chris@16:             boost::is_const<reference>,
Chris@16:             reference,
Chris@16:             const value_type&
Chris@16:             >::type
Chris@16:         >::type
Chris@16:     get(const compose_property_map &m, const key_type &k) {
Chris@16:         return get(m.f, get(m.g, k));
Chris@16:     }
Chris@16: 
Chris@16:     inline friend void
Chris@16:     put(const compose_property_map &m, const key_type &k, const value_type &v) {
Chris@16:         put(m.f, get(m.g, k), v);
Chris@16:     }
Chris@16: 
Chris@16: private:
Chris@16:     FPMap f;
Chris@16:     GPMap g;
Chris@16: };
Chris@16: 
Chris@16: template <class FPMap, class GPMap>
Chris@16: inline compose_property_map<FPMap, GPMap>
Chris@16: make_compose_property_map(const FPMap &f, const GPMap &g) {
Chris@16:     return compose_property_map<FPMap, GPMap>(f, g);
Chris@16: }
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // BOOST_PROPERTY_MAP_COMPOSE_PROPERTY_MAP_HPP