268 lines
9.4 KiB
C++
268 lines
9.4 KiB
C++
// Copyright (c) 2001-2011 Hartmut Kaiser
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// Copyright (c) 2010 Bryce Lelbach
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//
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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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#if !defined(BOOST_SPIRIT_LEX_STATE_SWITCHER_SEP_23_2007_0714PM)
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#define BOOST_SPIRIT_LEX_STATE_SWITCHER_SEP_23_2007_0714PM
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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/support/info.hpp>
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#include <boost/spirit/home/qi/detail/attributes.hpp>
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#include <boost/spirit/home/support/common_terminals.hpp>
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#include <boost/spirit/home/support/string_traits.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/qi/skip_over.hpp>
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#include <boost/spirit/home/qi/domain.hpp>
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#include <boost/spirit/home/qi/parser.hpp>
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#include <boost/spirit/home/qi/meta_compiler.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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// enables set_state(s)
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template <typename A0>
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struct use_terminal<qi::domain
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, terminal_ex<tag::set_state, fusion::vector1<A0> >
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> : traits::is_string<A0> {};
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// enables *lazy* set_state(s)
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template <>
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struct use_lazy_terminal<
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qi::domain, tag::set_state, 1
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> : mpl::true_ {};
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// enables in_state(s)[p]
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template <typename A0>
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struct use_directive<qi::domain
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, terminal_ex<tag::in_state, fusion::vector1<A0> >
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> : traits::is_string<A0> {};
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// enables *lazy* in_state(s)[p]
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template <>
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struct use_lazy_directive<
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qi::domain, tag::in_state, 1
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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::set_state;
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using spirit::in_state;
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#endif
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using spirit::set_state_type;
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using spirit::in_state_type;
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///////////////////////////////////////////////////////////////////////////
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namespace detail
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{
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template <typename Iterator>
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inline std::size_t
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set_lexer_state(Iterator& it, std::size_t state)
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{
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return it.set_state(state);
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}
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template <typename Iterator, typename Char>
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inline std::size_t
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set_lexer_state(Iterator& it, Char const* statename)
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{
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std::size_t state = it.map_state(statename);
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// If the following assertion fires you probably used the
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// set_state(...) or in_state(...)[...] lexer state switcher with
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// a lexer state name unknown to the lexer (no token definitions
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// have been associated with this lexer state).
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BOOST_ASSERT(std::size_t(~0) != state);
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return it.set_state(state);
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}
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}
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///////////////////////////////////////////////////////////////////////////
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// Parser switching the state of the underlying lexer component.
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// This parser gets used for the set_state(...) construct.
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///////////////////////////////////////////////////////////////////////////
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template <typename State>
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struct state_switcher
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: primitive_parser<state_switcher<State> >
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{
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typedef typename
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remove_const<typename traits::char_type_of<State>::type>::type
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char_type;
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typedef std::basic_string<char_type> string_type;
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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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state_switcher(char_type const* state)
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: state(state) {}
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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); // always do a pre-skip
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// just switch the state and return success
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detail::set_lexer_state(first, state.c_str());
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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("set_state");
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}
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string_type state;
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};
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///////////////////////////////////////////////////////////////////////////
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namespace detail
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{
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template <typename Iterator>
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struct reset_state_on_exit
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{
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template <typename State>
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reset_state_on_exit(Iterator& it_, State state_)
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: it(it_)
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, state(set_lexer_state(it_, traits::get_c_string(state_)))
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{}
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~reset_state_on_exit()
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{
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// reset the state of the underlying lexer instance
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set_lexer_state(it, state);
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}
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Iterator& it;
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std::size_t state;
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// silence MSVC warning C4512: assignment operator could not be generated
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BOOST_DELETED_FUNCTION(reset_state_on_exit& operator= (reset_state_on_exit const&))
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};
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}
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///////////////////////////////////////////////////////////////////////////
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// Parser, which switches the state of the underlying lexer component
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// for the execution of the embedded sub-parser, switching the state back
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// afterwards. This parser gets used for the in_state(...)[p] construct.
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///////////////////////////////////////////////////////////////////////////
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template <typename Subject, typename State>
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struct state_switcher_context
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: unary_parser<state_switcher_context<Subject, State> >
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{
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typedef Subject subject_type;
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typedef typename traits::char_type_of<State>::type char_type;
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typedef typename remove_const<char_type>::type non_const_char_type;
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template <typename Context, typename Iterator>
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struct attribute
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{
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typedef typename
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traits::attribute_of<subject_type, Context, Iterator>::type
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type;
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};
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state_switcher_context(Subject const& subject
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, typename add_reference<State>::type state)
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: subject(subject), state(state) {}
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// The following conversion constructors are needed to make the
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// in_state_switcher template usable
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template <typename String>
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state_switcher_context(
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state_switcher_context<Subject, String> const& rhs)
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: subject(rhs.subject), state(traits::get_c_string(rhs.state)) {}
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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); // always do a pre-skip
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// the state has to be reset at exit in any case
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detail::reset_state_on_exit<Iterator> guard(first, state);
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return subject.parse(first, last, context, skipper, attr);
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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("in_state", subject.what(context));
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}
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Subject subject;
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State state;
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// silence MSVC warning C4512: assignment operator could not be generated
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BOOST_DELETED_FUNCTION(state_switcher_context& operator= (state_switcher_context const&))
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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, typename State>
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struct make_primitive<terminal_ex<tag::set_state, fusion::vector1<State> >
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, Modifiers, typename enable_if<traits::is_string<State> >::type>
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{
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typedef typename add_const<State>::type const_string;
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typedef state_switcher<const_string> 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(traits::get_c_string(fusion::at_c<0>(term.args)));
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}
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};
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template <typename State, typename Subject, typename Modifiers>
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struct make_directive<terminal_ex<tag::in_state, fusion::vector1<State> >
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, Subject, Modifiers>
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{
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typedef typename add_const<State>::type const_string;
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typedef state_switcher_context<Subject, const_string> result_type;
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template <typename Terminal>
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result_type operator()(Terminal const& term, Subject const& subject
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, unused_type) const
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{
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return result_type(subject, fusion::at_c<0>(term.args));
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}
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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 Subject, typename State>
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struct has_semantic_action<qi::state_switcher_context<Subject, State> >
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: unary_has_semantic_action<Subject> {};
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///////////////////////////////////////////////////////////////////////////
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template <typename Subject, typename State, typename Attribute
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, typename Context, typename Iterator>
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struct handles_container<qi::state_switcher_context<Subject, State>
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, Attribute, Context, Iterator>
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: unary_handles_container<Subject, Attribute, Context, Iterator> {};
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}}}
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#endif
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