Chris@16: /*=============================================================================
Chris@16:   Copyright (c) 2001-2011 Joel de Guzman
Chris@16:   http://spirit.sourceforge.net/
Chris@16: 
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: #ifndef BOOST_SPIRIT_MODIFY_OCTOBER_25_2008_0142PM
Chris@16: #define BOOST_SPIRIT_MODIFY_OCTOBER_25_2008_0142PM
Chris@16: 
Chris@16: #if defined(_MSC_VER)
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/spirit/include/phoenix_limits.hpp>      // needs to be included before proto
Chris@16: #include <boost/proto/proto.hpp>
Chris@16: #include <boost/mpl/if.hpp>
Chris@16: #include <boost/type_traits/is_base_of.hpp>
Chris@16: #include <boost/spirit/home/support/unused.hpp>
Chris@16: 
Chris@16: namespace boost { namespace spirit
Chris@16: {
Chris@16:     template <typename Domain, typename T, typename Enable = void>
Chris@16:     struct is_modifier_directive;
Chris@16: 
Chris@16:     // Testing if a modifier set includes a modifier T involves
Chris@16:     // checking for inheritance (i.e. Modifiers is derived from T)
Chris@16:     template <typename Modifiers, typename T>
Chris@16:     struct has_modifier
Chris@16:         : is_base_of<T, Modifiers> {};
Chris@16: 
Chris@16:     // Adding modifiers is done using multi-inheritance
Chris@16:     template <typename Current, typename New, typename Enable = void>
Chris@16:     struct compound_modifier : Current, New
Chris@16:     {
Chris@16:         compound_modifier()
Chris@16:           : Current(), New() {}
Chris@16: 
Chris@16:         compound_modifier(Current const& current, New const& new_)
Chris@16:           : Current(current), New(new_) {}
Chris@16:     };
Chris@16: 
Chris@16:     // Don't add if New is already in Current
Chris@16:     template <typename Current, typename New>
Chris@16:     struct compound_modifier<
Chris@16:         Current, New, typename enable_if<has_modifier<Current, New> >::type>
Chris@16:       : Current
Chris@16:     {
Chris@16:         compound_modifier()
Chris@16:           : Current() {}
Chris@16: 
Chris@16:         compound_modifier(Current const& current, New const&)
Chris@16:           : Current(current) {}
Chris@16:     };
Chris@16: 
Chris@16:     // Special case if Current is unused_type
Chris@16:     template <typename New, typename Enable>
Chris@16:     struct compound_modifier<unused_type, New, Enable> : New
Chris@16:     {
Chris@16:         compound_modifier()
Chris@16:           : New() {}
Chris@16: 
Chris@16:         compound_modifier(unused_type, New const& new_)
Chris@16:           : New(new_) {}
Chris@16:     };
Chris@16: 
Chris@16:     // Domains may specialize this modify metafunction to allow
Chris@16:     // directives to add information to the Modifier template
Chris@16:     // parameter that is passed to the make_component metafunction.
Chris@16:     // By default, we return the modifiers untouched
Chris@16:     template <typename Domain, typename Enable = void>
Chris@16:     struct modify
Chris@16:     {
Chris@16:         template <typename Sig>
Chris@16:         struct result;
Chris@16: 
Chris@16:         template <typename This, typename Tag, typename Modifiers>
Chris@16:         struct result<This(Tag, Modifiers)>
Chris@16:         {
Chris@16:             typedef typename remove_const<
Chris@16:                 typename remove_reference<Tag>::type>::type
Chris@16:             tag_type;
Chris@16:             typedef typename remove_const<
Chris@16:                 typename remove_reference<Modifiers>::type>::type
Chris@16:             modifiers_type;
Chris@16: 
Chris@16:             typedef typename mpl::if_<
Chris@16:                 is_modifier_directive<Domain, tag_type>
Chris@16:               , compound_modifier<modifiers_type, tag_type>
Chris@16:               , Modifiers>::type
Chris@16:             type;
Chris@16:         };
Chris@16: 
Chris@16:         template <typename Tag, typename Modifiers>
Chris@16:         typename result<modify(Tag, Modifiers)>::type
Chris@16:         operator()(Tag tag, Modifiers modifiers) const
Chris@16:         {
Chris@16:             return op(tag, modifiers, is_modifier_directive<Domain, Tag>());
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Tag, typename Modifiers>
Chris@16:         Modifiers
Chris@16:         op(Tag /*tag*/, Modifiers modifiers, mpl::false_) const
Chris@16:         {
Chris@16:             return modifiers;
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Tag, typename Modifiers>
Chris@16:         compound_modifier<Modifiers, Tag>
Chris@16:         op(Tag tag, Modifiers modifiers, mpl::true_) const
Chris@16:         {
Chris@16:             return compound_modifier<Modifiers, Tag>(modifiers, tag);
Chris@16:         }
Chris@16:     };
Chris@16: }}
Chris@16: 
Chris@16: namespace boost { namespace proto
Chris@16: {
Chris@16:     template <typename Domain, typename Enable>
Chris@16:     struct is_callable<spirit::modify<Domain, Enable> >
Chris@16:       : mpl::true_ {};
Chris@16: }}
Chris@16: 
Chris@16: #endif