133 lines
4.0 KiB
C++
133 lines
4.0 KiB
C++
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/*=============================================================================
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Copyright (c) 2001-2011 Joel de Guzman
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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(BOOST_SPIRIT_EPS_MARCH_23_2007_0454PM)
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#define BOOST_SPIRIT_EPS_MARCH_23_2007_0454PM
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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/domain.hpp>
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#include <boost/spirit/home/qi/skip_over.hpp>
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#include <boost/spirit/home/qi/meta_compiler.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/spirit/home/support/common_terminals.hpp>
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#include <boost/fusion/include/at.hpp>
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#include <boost/type_traits/is_convertible.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_terminal<qi::domain, tag::eps> // enables eps
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: mpl::true_ {};
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template <typename A0>
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struct use_terminal<qi::domain
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, terminal_ex<tag::eps, fusion::vector1<A0> > // enables eps(bool-condition)
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> : is_convertible<A0, bool> {};
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template <> // enables eps(f)
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struct use_lazy_terminal<
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qi::domain, tag::eps, 1 /*arity*/
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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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#ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
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using spirit::eps;
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#endif
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using spirit::eps_type;
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struct eps_parser : primitive_parser<eps_parser>
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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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typedef unused_type type;
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};
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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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qi::skip_over(first, last, skipper);
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return true;
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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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return info("eps");
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}
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};
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struct semantic_predicate : primitive_parser<semantic_predicate>
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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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typedef unused_type type;
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};
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semantic_predicate(bool predicate_)
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: predicate(predicate_) {}
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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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qi::skip_over(first, last, skipper);
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return predicate;
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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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return info("semantic-predicate");
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}
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bool predicate;
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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 Modifiers>
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struct make_primitive<tag::eps, Modifiers>
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{
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typedef eps_parser result_type;
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result_type operator()(unused_type, unused_type) const
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{
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return result_type();
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}
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};
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template <typename Modifiers, typename A0>
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struct make_primitive<
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terminal_ex<tag::eps, fusion::vector1<A0> >
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, Modifiers>
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{
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typedef semantic_predicate result_type;
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template <typename Terminal>
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result_type operator()(Terminal const& term, unused_type) const
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{
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return result_type(fusion::at_c<0>(term.args) ? true : false);
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}
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};
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}}}
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#endif
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