| // Copyright (c) 2001-2009 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) && (_MSC_VER >= 1020) |
| #pragma once // MS compatible compilers support #pragma once |
| #endif |
| |
| #include <boost/spirit/home/qi/domain.hpp> |
| #include <boost/spirit/home/lex/set_state.hpp> |
| #include <boost/spirit/home/support/attribute_of.hpp> |
| #include <boost/spirit/home/support/detail/to_narrow.hpp> |
| |
| namespace boost { namespace spirit { namespace qi |
| { |
| /////////////////////////////////////////////////////////////////////////// |
| // parser, which switches the state of the underlying lexer component |
| // this parser gets used for the set_state(...) construct. |
| /////////////////////////////////////////////////////////////////////////// |
| 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(static_cast<std::size_t>(~0) != state); |
| return it.set_state(state); |
| } |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| struct state_switcher |
| { |
| template <typename Component, typename Context, typename Iterator> |
| struct attribute |
| { |
| typedef unused_type type; |
| }; |
| |
| template < |
| typename Component |
| , typename Iterator, typename Context |
| , typename Skipper, typename Attribute> |
| static bool parse( |
| Component const& component |
| , Iterator& first, Iterator const& last |
| , Context& /*context*/, Skipper const& skipper |
| , Attribute& /*attr*/) |
| { |
| qi::skip(first, last, skipper); // always do a pre-skip |
| |
| // just switch the state and return success |
| detail::set_lexer_state(first, spirit::left(component).name); |
| return true; |
| } |
| |
| template <typename Component, typename Context> |
| static std::string what(Component const& component, Context const& ctx) |
| { |
| std::string result("set_state(\""); |
| result += spirit::detail::to_narrow_string( |
| spirit::left(component).name); |
| result += "\")"; |
| return result; |
| } |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // 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. |
| /////////////////////////////////////////////////////////////////////////// |
| 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_, state_)) |
| { |
| } |
| ~reset_state_on_exit() |
| { |
| // reset the state of the underlying lexer instance |
| it.set_state(state); |
| } |
| |
| Iterator& it; |
| std::size_t state; |
| }; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| struct state_switcher_context |
| { |
| template <typename Component, typename Context, typename Iterator> |
| struct attribute |
| { |
| typedef typename |
| result_of::subject<Component>::type |
| subject_type; |
| |
| typedef typename |
| traits::attribute_of< |
| qi::domain, subject_type, Context, Iterator>::type |
| type; |
| }; |
| |
| template < |
| typename Component |
| , typename Iterator, typename Context |
| , typename Skipper, typename Attribute> |
| static bool parse( |
| Component const& component |
| , Iterator& first, Iterator const& last |
| , Context& context, Skipper const& skipper |
| , Attribute& attr) |
| { |
| qi::skip(first, last, skipper); // always do a pre-skip |
| |
| typedef typename |
| spirit::result_of::subject<Component>::type::director |
| director; |
| |
| // the state has to be reset at exit in any case |
| detail::reset_state_on_exit<Iterator> guard( |
| first, proto::child_c<0>(argument1(component)).name); |
| |
| return director::parse(spirit::subject(component), first, |
| last, context, skipper, attr); |
| } |
| |
| template <typename Component, typename Context> |
| static std::string what(Component const& component, Context const& ctx) |
| { |
| std::string result("in_state(\""); |
| result += spirit::detail::to_narrow_string( |
| proto::child_c<0>(argument1(component)).name); |
| result += "\")["; |
| |
| typedef typename |
| spirit::result_of::subject<Component>::type::director |
| director; |
| |
| result += director::what(subject(component), ctx); |
| result += "]"; |
| return result; |
| } |
| }; |
| |
| }}} |
| |
| #endif |