98 lines
3.7 KiB
C++
Executable File
98 lines
3.7 KiB
C++
Executable File
/*=============================================================================
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Copyright (c) 2001-2007 Joel de Guzman
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Copyright (c) 2001-2008 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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#if !defined(SPIRIT_ALTERNATIVE_FEB_05_2007_1153AM)
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#define SPIRIT_ALTERNATIVE_FEB_05_2007_1153AM
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#include <boost/spirit/home/qi/detail/alternative_function.hpp>
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#include <boost/spirit/home/support/attribute_transform.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/as_variant.hpp>
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#include <boost/fusion/include/any.hpp>
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#include <boost/fusion/include/vector.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/fusion/include/push_front.hpp>
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#include <boost/variant.hpp>
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#include <boost/type_traits/is_same.hpp>
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#include <boost/mpl/end.hpp>
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#include <boost/mpl/find_if.hpp>
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#include <boost/mpl/eval_if.hpp>
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#include <boost/mpl/identity.hpp>
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namespace boost { namespace spirit { namespace qi
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{
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struct alternative
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{
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template <typename T>
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struct transform_child : mpl::identity<T> {};
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template <typename All, typename Filtered>
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struct build_container
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{
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// if the original attribute list does not contain any unused
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// attributes it is used, otherwise a single unused_type is
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// pushed to the front the list. This is to make sure that if
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// there is an unused in the list it is the first one.
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typedef typename
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mpl::find_if<All, is_same<mpl::_, unused_type> >::type
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unused_;
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typedef typename
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mpl::eval_if<
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is_same<unused_, typename mpl::end<All>::type>,
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mpl::identity<All>,
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fusion::result_of::push_front<Filtered, unused_type>
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>::type
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attribute_sequence;
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// Ok, now make a variant over the attribute_sequence. It's
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// a pity that make_variant_over does not support forward MPL
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// sequences. We use our own conversion metaprogram (as_variant).
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typedef typename
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as_variant<attribute_sequence>::type
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type;
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};
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template <typename Component, typename Context, typename Iterator>
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struct attribute :
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build_fusion_sequence<alternative, Component, Iterator, Context>
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{
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};
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template <
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typename Component
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, typename Iterator, typename Context
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, typename Skipper, typename Attribute>
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static bool parse(
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Component const& component
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, Iterator& first, Iterator const& last
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, Context& context, Skipper const& skipper
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, Attribute& attr)
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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(component.elements, f);
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}
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template <typename Component, typename Context>
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static std::string what(Component const& component, Context const& ctx)
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{
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std::string result = "alternatives[";
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fusion::for_each(component.elements,
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spirit::detail::what_function<Context>(result, ctx));
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result += "]";
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return result;
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}
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};
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}}}
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#endif
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