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