Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2001-2011 Joel de Guzman
Chris@16:     Copyright (c) 2001-2011 Hartmut Kaiser
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: #if !defined(SPIRIT_ALTERNATIVE_FEBRUARY_05_2007_1153AM)
Chris@16: #define SPIRIT_ALTERNATIVE_FEBRUARY_05_2007_1153AM
Chris@16: 
Chris@16: #if defined(_MSC_VER)
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/spirit/home/qi/detail/alternative_function.hpp>
Chris@16: #include <boost/spirit/home/qi/meta_compiler.hpp>
Chris@16: #include <boost/spirit/home/qi/parser.hpp>
Chris@16: #include <boost/spirit/home/qi/detail/attributes.hpp>
Chris@16: #include <boost/spirit/home/support/has_semantic_action.hpp>
Chris@16: #include <boost/spirit/home/support/handles_container.hpp>
Chris@16: #include <boost/spirit/home/support/detail/what_function.hpp>
Chris@16: #include <boost/spirit/home/support/unused.hpp>
Chris@16: #include <boost/spirit/home/support/info.hpp>
Chris@16: #include <boost/fusion/include/any.hpp>
Chris@16: #include <boost/fusion/include/mpl.hpp>
Chris@16: #include <boost/fusion/include/for_each.hpp>
Chris@16: 
Chris@16: namespace boost { namespace spirit
Chris@16: {
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     // Enablers
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <>
Chris@16:     struct use_operator<qi::domain, proto::tag::bitwise_or> // enables |
Chris@16:       : mpl::true_ {};
Chris@16: 
Chris@16:     template <>
Chris@16:     struct flatten_tree<qi::domain, proto::tag::bitwise_or> // flattens |
Chris@16:       : mpl::true_ {};
Chris@16: }}
Chris@16: 
Chris@16: namespace boost { namespace spirit { namespace qi
Chris@16: {
Chris@16:     template <typename Elements>
Chris@16:     struct alternative : nary_parser<alternative<Elements> >
Chris@16:     {
Chris@16:         template <typename Context, typename Iterator>
Chris@16:         struct attribute
Chris@16:         {
Chris@16:             // Put all the element attributes in a tuple
Chris@16:             typedef typename traits::build_attribute_sequence<
Chris@16:                 Elements, Context, traits::alternative_attribute_transform
Chris@16:               , Iterator, qi::domain
Chris@16:             >::type all_attributes;
Chris@16: 
Chris@16:             // Ok, now make a variant over the attribute sequence. Note that
Chris@16:             // build_variant makes sure that 1) all attributes in the variant
Chris@16:             // are unique 2) puts the unused attribute, if there is any, to
Chris@16:             // the front and 3) collapses single element variants, variant<T>
Chris@16:             // to T.
Chris@16:             typedef typename
Chris@16:                 traits::build_variant<all_attributes>::type
Chris@16:             type;
Chris@16:         };
Chris@16: 
Chris@16:         alternative(Elements const& elements_)
Chris@16:           : elements(elements_) {}
Chris@16: 
Chris@16:         template <typename Iterator, typename Context
Chris@16:           , typename Skipper, typename Attribute>
Chris@16:         bool parse(Iterator& first, Iterator const& last
Chris@16:           , Context& context, Skipper const& skipper
Chris@16:           , Attribute& attr_) const
Chris@16:         {
Chris@16:             detail::alternative_function<Iterator, Context, Skipper, Attribute>
Chris@16:                 f(first, last, context, skipper, attr_);
Chris@16: 
Chris@16:             // return true if *any* of the parsers succeed
Chris@16:             return fusion::any(elements, f);
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Context>
Chris@16:         info what(Context& context) const
Chris@16:         {
Chris@16:             info result("alternative");
Chris@16:             fusion::for_each(elements,
Chris@16:                 spirit::detail::what_function<Context>(result, context));
Chris@16:             return result;
Chris@16:         }
Chris@16: 
Chris@16:         Elements elements;
Chris@16:     };
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     // Parser generators: make_xxx function (objects)
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Elements, typename Modifiers>
Chris@16:     struct make_composite<proto::tag::bitwise_or, Elements, Modifiers>
Chris@16:       : make_nary_composite<Elements, alternative>
Chris@16:     {};
Chris@16: }}}
Chris@16: 
Chris@16: namespace boost { namespace spirit { namespace traits
Chris@16: {
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Elements>
Chris@16:     struct has_semantic_action<qi::alternative<Elements> >
Chris@16:       : nary_has_semantic_action<Elements> {};
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Elements, typename Attribute, typename Context
Chris@16:       , typename Iterator>
Chris@16:     struct handles_container<qi::alternative<Elements>, Attribute, Context
Chris@16:       , Iterator>
Chris@16:       : nary_handles_container<Elements, Attribute, Context, Iterator> {};
Chris@16: }}}
Chris@16: 
Chris@16: #endif