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