Chris@16: //  Copyright (c) 2001-2011 Hartmut Kaiser
Chris@16: //  Copyright (c)      2010 Bryce Lelbach
Chris@16: //
Chris@16: //  Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #if !defined(BOOST_SPIRIT_LEX_STATE_SWITCHER_SEP_23_2007_0714PM)
Chris@16: #define BOOST_SPIRIT_LEX_STATE_SWITCHER_SEP_23_2007_0714PM
Chris@16: 
Chris@16: #if defined(_MSC_VER)
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/spirit/home/support/info.hpp>
Chris@16: #include <boost/spirit/home/qi/detail/attributes.hpp>
Chris@16: #include <boost/spirit/home/support/common_terminals.hpp>
Chris@16: #include <boost/spirit/home/support/string_traits.hpp>
Chris@16: #include <boost/spirit/home/support/has_semantic_action.hpp>
Chris@16: #include <boost/spirit/home/support/handles_container.hpp>
Chris@16: #include <boost/spirit/home/qi/skip_over.hpp>
Chris@16: #include <boost/spirit/home/qi/domain.hpp>
Chris@16: #include <boost/spirit/home/qi/parser.hpp>
Chris@16: #include <boost/spirit/home/qi/meta_compiler.hpp>
Chris@16: #include <boost/mpl/print.hpp>
Chris@16: 
Chris@16: namespace boost { namespace spirit
Chris@16: {
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     // Enablers
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16: 
Chris@16:     // enables set_state(s)
Chris@16:     template <typename A0>
Chris@16:     struct use_terminal<qi::domain
Chris@16:       , terminal_ex<tag::set_state, fusion::vector1<A0> >
Chris@16:     > : traits::is_string<A0> {};
Chris@16: 
Chris@16:     // enables *lazy* set_state(s)
Chris@16:     template <>
Chris@16:     struct use_lazy_terminal<
Chris@16:         qi::domain, tag::set_state, 1
Chris@16:     > : mpl::true_ {};
Chris@16: 
Chris@16:     // enables in_state(s)[p]
Chris@16:     template <typename A0>
Chris@16:     struct use_directive<qi::domain
Chris@16:       , terminal_ex<tag::in_state, fusion::vector1<A0> >
Chris@16:     > : traits::is_string<A0> {};
Chris@16: 
Chris@16:     // enables *lazy* in_state(s)[p]
Chris@16:     template <>
Chris@16:     struct use_lazy_directive<
Chris@16:         qi::domain, tag::in_state, 1
Chris@16:     > : mpl::true_ {};
Chris@16: 
Chris@16: }}
Chris@16: 
Chris@16: namespace boost { namespace spirit { namespace qi
Chris@16: {
Chris@16: #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
Chris@16:     using spirit::set_state;
Chris@16:     using spirit::in_state;
Chris@16: #endif
Chris@16:     using spirit::set_state_type;
Chris@16:     using spirit::in_state_type;
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     namespace detail
Chris@16:     {
Chris@16:         template <typename Iterator>
Chris@16:         inline std::size_t
Chris@16:         set_lexer_state(Iterator& it, std::size_t state)
Chris@16:         {
Chris@16:             return it.set_state(state);
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Iterator, typename Char>
Chris@16:         inline std::size_t
Chris@16:         set_lexer_state(Iterator& it, Char const* statename)
Chris@16:         {
Chris@16:             std::size_t state = it.map_state(statename);
Chris@16: 
Chris@16:             //  If the following assertion fires you probably used the
Chris@16:             //  set_state(...) or in_state(...)[...] lexer state switcher with
Chris@16:             //  a lexer state name unknown to the lexer (no token definitions
Chris@16:             //  have been associated with this lexer state).
Chris@16:             BOOST_ASSERT(std::size_t(~0) != state);
Chris@16:             return it.set_state(state);
Chris@16:         }
Chris@16:     }
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     //  Parser switching the state of the underlying lexer component.
Chris@16:     //  This parser gets used for the set_state(...) construct.
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename State>
Chris@16:     struct state_switcher
Chris@16:       : primitive_parser<state_switcher<State> >
Chris@16:     {
Chris@16:         typedef typename 
Chris@16:             remove_const<typename traits::char_type_of<State>::type>::type 
Chris@16:         char_type;
Chris@16:         typedef std::basic_string<char_type> string_type;
Chris@16: 
Chris@16:         template <typename Context, typename Iterator>
Chris@16:         struct attribute
Chris@16:         {
Chris@16:             typedef unused_type type;
Chris@16:         };
Chris@16: 
Chris@16:         state_switcher(char_type const* state)
Chris@16:           : state(state) {}
Chris@16: 
Chris@16:         template <typename Iterator, typename Context
Chris@16:           , typename Skipper, typename Attribute>
Chris@16:         bool parse(Iterator& first, Iterator const& last
Chris@16:           , Context& /*context*/, Skipper const& skipper
Chris@16:           , Attribute& /*attr*/) const
Chris@16:         {
Chris@16:             qi::skip_over(first, last, skipper);   // always do a pre-skip
Chris@16: 
Chris@16:             // just switch the state and return success
Chris@16:             detail::set_lexer_state(first, state.c_str());
Chris@16:             return true;
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Context>
Chris@16:         info what(Context& /*context*/) const
Chris@16:         {
Chris@16:             return info("set_state");
Chris@16:         }
Chris@16: 
Chris@16:         string_type state;
Chris@16:     };
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     namespace detail
Chris@16:     {
Chris@16:         template <typename Iterator>
Chris@16:         struct reset_state_on_exit
Chris@16:         {
Chris@16:             template <typename State>
Chris@16:             reset_state_on_exit(Iterator& it_, State state_)
Chris@16:               : it(it_)
Chris@16:               , state(set_lexer_state(it_, traits::get_c_string(state_))) 
Chris@16:             {}
Chris@16: 
Chris@16:             ~reset_state_on_exit()
Chris@16:             {
Chris@16:                 // reset the state of the underlying lexer instance
Chris@16:                 set_lexer_state(it, state);
Chris@16:             }
Chris@16: 
Chris@16:             Iterator& it;
Chris@16:             std::size_t state;
Chris@16: 
Chris@16:         private:
Chris@16:             // silence MSVC warning C4512: assignment operator could not be generated
Chris@16:             reset_state_on_exit& operator= (reset_state_on_exit const&);
Chris@16:         };
Chris@16:     }
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     // Parser, which switches the state of the underlying lexer component
Chris@16:     // for the execution of the embedded sub-parser, switching the state back
Chris@16:     // afterwards. This parser gets used for the in_state(...)[p] construct.
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Subject, typename State>
Chris@16:     struct state_switcher_context 
Chris@16:       : unary_parser<state_switcher_context<Subject, State> >
Chris@16:     {
Chris@16:         typedef Subject subject_type;
Chris@16:         typedef typename traits::char_type_of<State>::type char_type;
Chris@16:         typedef typename remove_const<char_type>::type non_const_char_type;
Chris@16: 
Chris@16:         template <typename Context, typename Iterator>
Chris@16:         struct attribute
Chris@16:         {
Chris@16:             typedef typename
Chris@16:                 traits::attribute_of<subject_type, Context, Iterator>::type
Chris@16:             type;
Chris@16:         };
Chris@16: 
Chris@16:         state_switcher_context(Subject const& subject
Chris@16:               , typename add_reference<State>::type state)
Chris@16:           : subject(subject), state(state) {}
Chris@16: 
Chris@16:         // The following conversion constructors are needed to make the 
Chris@16:         // in_state_switcher template usable
Chris@16:         template <typename String>
Chris@16:         state_switcher_context(
Chris@16:                 state_switcher_context<Subject, String> const& rhs)
Chris@16:           : subject(rhs.subject), state(traits::get_c_string(rhs.state)) {}
Chris@16: 
Chris@16:         template <typename Iterator, typename Context
Chris@16:           , typename Skipper, typename Attribute>
Chris@16:         bool parse(Iterator& first, Iterator const& last
Chris@16:           , Context& context, Skipper const& skipper
Chris@16:           , Attribute& attr) const
Chris@16:         {
Chris@16:             qi::skip_over(first, last, skipper);   // always do a pre-skip
Chris@16: 
Chris@16:             // the state has to be reset at exit in any case
Chris@16:             detail::reset_state_on_exit<Iterator> guard(first, state);
Chris@16:             return subject.parse(first, last, context, skipper, attr);
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Context>
Chris@16:         info what(Context& context) const
Chris@16:         {
Chris@16:             return info("in_state", subject.what(context));
Chris@16:         }
Chris@16: 
Chris@16:         Subject subject;
Chris@16:         State state;
Chris@16: 
Chris@16:     private:
Chris@16:         // silence MSVC warning C4512: assignment operator could not be generated
Chris@16:         state_switcher_context& operator= (state_switcher_context const&);
Chris@16:     };
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     // Parser generators: make_xxx function (objects)
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Modifiers, typename State>
Chris@16:     struct make_primitive<terminal_ex<tag::set_state, fusion::vector1<State> >
Chris@16:       , Modifiers, typename enable_if<traits::is_string<State> >::type>
Chris@16:     {
Chris@16:         typedef typename add_const<State>::type const_string;
Chris@16:         typedef state_switcher<const_string> result_type;
Chris@16: 
Chris@16:         template <typename Terminal>
Chris@16:         result_type operator()(Terminal const& term, unused_type) const
Chris@16:         {
Chris@16:             return result_type(traits::get_c_string(fusion::at_c<0>(term.args)));
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template <typename State, typename Subject, typename Modifiers>
Chris@16:     struct make_directive<terminal_ex<tag::in_state, fusion::vector1<State> >
Chris@16:       , Subject, Modifiers>
Chris@16:     {
Chris@16:         typedef typename add_const<State>::type const_string;
Chris@16:         typedef state_switcher_context<Subject, const_string> result_type;
Chris@16: 
Chris@16:         template <typename Terminal>
Chris@16:         result_type operator()(Terminal const& term, Subject const& subject
Chris@16:           , unused_type) const
Chris@16:         {
Chris@16:             return result_type(subject, fusion::at_c<0>(term.args));
Chris@16:         }
Chris@16:     };
Chris@16: }}}
Chris@16: 
Chris@16: namespace boost { namespace spirit { namespace traits
Chris@16: {
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Subject, typename State>
Chris@16:     struct has_semantic_action<qi::state_switcher_context<Subject, State> >
Chris@16:       : unary_has_semantic_action<Subject> {};
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Subject, typename State, typename Attribute
Chris@16:         , typename Context, typename Iterator>
Chris@16:     struct handles_container<qi::state_switcher_context<Subject, State>
Chris@16:           , Attribute, Context, Iterator>
Chris@16:       : unary_handles_container<Subject, Attribute, Context, Iterator> {}; 
Chris@16: }}}
Chris@16: 
Chris@16: #endif