| /*============================================================================= |
| Copyright (c) 2001-2010 Joel de Guzman |
| |
| 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_EPS_MARCH_23_2007_0454PM) |
| #define BOOST_SPIRIT_EPS_MARCH_23_2007_0454PM |
| |
| #if defined(_MSC_VER) |
| #pragma once |
| #endif |
| |
| #include <boost/spirit/home/qi/domain.hpp> |
| #include <boost/spirit/home/qi/skip_over.hpp> |
| #include <boost/spirit/home/qi/meta_compiler.hpp> |
| #include <boost/spirit/home/support/unused.hpp> |
| #include <boost/spirit/home/support/info.hpp> |
| #include <boost/spirit/home/support/common_terminals.hpp> |
| #include <boost/fusion/include/at.hpp> |
| #include <boost/type_traits/is_convertible.hpp> |
| |
| namespace boost { namespace spirit |
| { |
| /////////////////////////////////////////////////////////////////////////// |
| // Enablers |
| /////////////////////////////////////////////////////////////////////////// |
| template <> |
| struct use_terminal<qi::domain, tag::eps> // enables eps |
| : mpl::true_ {}; |
| |
| template <typename A0> |
| struct use_terminal<qi::domain |
| , terminal_ex<tag::eps, fusion::vector1<A0> > // enables eps(bool-condition) |
| > : is_convertible<A0, bool> {}; |
| |
| template <> // enables eps(f) |
| struct use_lazy_terminal< |
| qi::domain, tag::eps, 1 /*arity*/ |
| > : mpl::true_ {}; |
| }} |
| |
| namespace boost { namespace spirit { namespace qi |
| { |
| using spirit::eps; |
| using spirit::eps_type; |
| |
| struct eps_parser : primitive_parser<eps_parser> |
| { |
| template <typename Context, typename Iterator> |
| struct attribute |
| { |
| typedef unused_type type; |
| }; |
| |
| 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); |
| return true; |
| } |
| |
| template <typename Context> |
| info what(Context& /*context*/) const |
| { |
| return info("eps"); |
| } |
| }; |
| |
| struct semantic_predicate : primitive_parser<semantic_predicate> |
| { |
| template <typename Context, typename Iterator> |
| struct attribute |
| { |
| typedef unused_type type; |
| }; |
| |
| semantic_predicate(bool predicate) |
| : predicate(predicate) {} |
| |
| 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); |
| return predicate; |
| } |
| |
| template <typename Context> |
| info what(Context& /*context*/) const |
| { |
| return info("semantic-predicate"); |
| } |
| |
| bool predicate; |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Parser generators: make_xxx function (objects) |
| /////////////////////////////////////////////////////////////////////////// |
| template <typename Modifiers> |
| struct make_primitive<tag::eps, Modifiers> |
| { |
| typedef eps_parser result_type; |
| result_type operator()(unused_type, unused_type) const |
| { |
| return result_type(); |
| } |
| }; |
| |
| template <typename Modifiers, typename A0> |
| struct make_primitive< |
| terminal_ex<tag::eps, fusion::vector1<A0> > |
| , Modifiers> |
| { |
| typedef semantic_predicate result_type; |
| template <typename Terminal> |
| result_type operator()(Terminal const& term, unused_type) const |
| { |
| return result_type(fusion::at_c<0>(term.args) ? true : false); |
| } |
| }; |
| }}} |
| |
| #endif |