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