| /*============================================================================= |
| Copyright (c) 2001-2007 Joel de Guzman |
| Copyright (c) 2001-2009 Hartmut Kaiser |
| |
| 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) |
| =============================================================================*/ |
| #if !defined(SPIRIT_ALTERNATIVE_FEB_05_2007_1153AM) |
| #define SPIRIT_ALTERNATIVE_FEB_05_2007_1153AM |
| |
| #include <boost/spirit/home/qi/detail/alternative_function.hpp> |
| #include <boost/spirit/home/support/attribute_transform.hpp> |
| #include <boost/spirit/home/support/detail/what_function.hpp> |
| #include <boost/spirit/home/support/unused.hpp> |
| #include <boost/spirit/home/support/as_variant.hpp> |
| #include <boost/fusion/include/any.hpp> |
| #include <boost/fusion/include/vector.hpp> |
| #include <boost/fusion/include/mpl.hpp> |
| #include <boost/fusion/include/for_each.hpp> |
| #include <boost/fusion/include/push_front.hpp> |
| #include <boost/variant.hpp> |
| #include <boost/type_traits/is_same.hpp> |
| #include <boost/mpl/end.hpp> |
| #include <boost/mpl/find_if.hpp> |
| #include <boost/mpl/eval_if.hpp> |
| #include <boost/mpl/identity.hpp> |
| |
| namespace boost { namespace spirit { namespace qi |
| { |
| struct alternative |
| { |
| template <typename T> |
| struct transform_child : mpl::identity<T> {}; |
| |
| template <typename All, typename Filtered> |
| struct build_container |
| { |
| // if the original attribute list does not contain any unused |
| // attributes it is used, otherwise a single unused_type is |
| // pushed to the front the list. This is to make sure that if |
| // there is an unused in the list it is the first one. |
| typedef typename |
| mpl::find_if<All, is_same<mpl::_, unused_type> >::type |
| unused_; |
| |
| typedef typename |
| mpl::eval_if< |
| is_same<unused_, typename mpl::end<All>::type>, |
| mpl::identity<All>, |
| fusion::result_of::push_front<Filtered, unused_type> |
| >::type |
| attribute_sequence; |
| |
| // Ok, now make a variant over the attribute_sequence. It's |
| // a pity that make_variant_over does not support forward MPL |
| // sequences. We use our own conversion metaprogram (as_variant). |
| typedef typename |
| as_variant<attribute_sequence>::type |
| type; |
| }; |
| |
| template <typename Component, typename Context, typename Iterator> |
| struct attribute : |
| build_fusion_sequence<alternative, Component, Iterator, Context> |
| { |
| }; |
| |
| template < |
| typename Component |
| , typename Iterator, typename Context |
| , typename Skipper, typename Attribute> |
| static bool parse( |
| Component const& component |
| , Iterator& first, Iterator const& last |
| , Context& context, Skipper const& skipper |
| , Attribute& attr) |
| { |
| detail::alternative_function<Iterator, Context, Skipper, Attribute> |
| f(first, last, context, skipper, attr); |
| |
| // return true if *any* of the parsers succeed |
| return fusion::any(component.elements, f); |
| } |
| |
| template <typename Component, typename Context> |
| static std::string what(Component const& component, Context const& ctx) |
| { |
| std::string result = "alternatives["; |
| fusion::for_each(component.elements, |
| spirit::detail::what_function<Context>(result, ctx)); |
| result += "]"; |
| return result; |
| } |
| }; |
| }}} |
| |
| #endif |