121 lines
4.5 KiB
C++
121 lines
4.5 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2011 Joel de Guzman
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Copyright (c) 2001-2011 Hartmut Kaiser
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef BOOST_SPIRIT_QI_OPERATOR_ALTERNATIVE_HPP
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#define BOOST_SPIRIT_QI_OPERATOR_ALTERNATIVE_HPP
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#if defined(_MSC_VER)
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#pragma once
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#endif
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#include <boost/spirit/home/qi/detail/alternative_function.hpp>
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#include <boost/spirit/home/qi/meta_compiler.hpp>
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#include <boost/spirit/home/qi/parser.hpp>
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#include <boost/spirit/home/qi/detail/attributes.hpp>
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#include <boost/spirit/home/support/has_semantic_action.hpp>
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#include <boost/spirit/home/support/handles_container.hpp>
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#include <boost/spirit/home/support/detail/what_function.hpp>
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#include <boost/spirit/home/support/unused.hpp>
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#include <boost/spirit/home/support/info.hpp>
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#include <boost/fusion/include/any.hpp>
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#include <boost/fusion/include/mpl.hpp>
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#include <boost/fusion/include/for_each.hpp>
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#include <boost/proto/operators.hpp>
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#include <boost/proto/tags.hpp>
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namespace boost { namespace spirit
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{
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///////////////////////////////////////////////////////////////////////////
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// Enablers
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///////////////////////////////////////////////////////////////////////////
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template <>
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struct use_operator<qi::domain, proto::tag::bitwise_or> // enables |
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: mpl::true_ {};
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template <>
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struct flatten_tree<qi::domain, proto::tag::bitwise_or> // flattens |
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: mpl::true_ {};
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}}
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namespace boost { namespace spirit { namespace qi
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{
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template <typename Elements>
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struct alternative : nary_parser<alternative<Elements> >
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{
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template <typename Context, typename Iterator>
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struct attribute
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{
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// Put all the element attributes in a tuple
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typedef typename traits::build_attribute_sequence<
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Elements, Context, traits::alternative_attribute_transform
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, Iterator, qi::domain
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>::type all_attributes;
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// Ok, now make a variant over the attribute sequence. Note that
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// build_variant makes sure that 1) all attributes in the variant
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// are unique 2) puts the unused attribute, if there is any, to
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// the front and 3) collapses single element variants, variant<T>
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// to T.
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typedef typename
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traits::build_variant<all_attributes>::type
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type;
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};
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alternative(Elements const& elements_)
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: elements(elements_) {}
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template <typename Iterator, typename Context
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, typename Skipper, typename Attribute>
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bool parse(Iterator& first, Iterator const& last
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, Context& context, Skipper const& skipper
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, Attribute& attr_) const
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{
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detail::alternative_function<Iterator, Context, Skipper, Attribute>
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f(first, last, context, skipper, attr_);
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// return true if *any* of the parsers succeed
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return fusion::any(elements, f);
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}
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template <typename Context>
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info what(Context& context) const
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{
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info result("alternative");
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fusion::for_each(elements,
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spirit::detail::what_function<Context>(result, context));
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return result;
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}
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Elements elements;
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};
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///////////////////////////////////////////////////////////////////////////
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// Parser generators: make_xxx function (objects)
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///////////////////////////////////////////////////////////////////////////
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template <typename Elements, typename Modifiers>
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struct make_composite<proto::tag::bitwise_or, Elements, Modifiers>
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: make_nary_composite<Elements, alternative>
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{};
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}}}
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namespace boost { namespace spirit { namespace traits
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{
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///////////////////////////////////////////////////////////////////////////
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template <typename Elements>
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struct has_semantic_action<qi::alternative<Elements> >
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: nary_has_semantic_action<Elements> {};
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///////////////////////////////////////////////////////////////////////////
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template <typename Elements, typename Attribute, typename Context
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, typename Iterator>
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struct handles_container<qi::alternative<Elements>, Attribute, Context
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, Iterator>
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: nary_handles_container<Elements, Attribute, Context, Iterator> {};
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}}}
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#endif
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