Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2001-2011 Joel de Guzman
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_EPS_MARCH_23_2007_0454PM)
Chris@16: #define BOOST_SPIRIT_EPS_MARCH_23_2007_0454PM
Chris@16: 
Chris@16: #if defined(_MSC_VER)
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/spirit/home/qi/domain.hpp>
Chris@16: #include <boost/spirit/home/qi/skip_over.hpp>
Chris@16: #include <boost/spirit/home/qi/meta_compiler.hpp>
Chris@16: #include <boost/spirit/home/support/unused.hpp>
Chris@16: #include <boost/spirit/home/support/info.hpp>
Chris@16: #include <boost/spirit/home/support/common_terminals.hpp>
Chris@16: #include <boost/fusion/include/at.hpp>
Chris@16: #include <boost/type_traits/is_convertible.hpp>
Chris@16: 
Chris@16: namespace boost { namespace spirit
Chris@16: {
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     // Enablers
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <>
Chris@16:     struct use_terminal<qi::domain, tag::eps>       // enables eps
Chris@16:       : mpl::true_ {};
Chris@16: 
Chris@16:     template <typename A0>
Chris@16:     struct use_terminal<qi::domain
Chris@16:       , terminal_ex<tag::eps, fusion::vector1<A0> > // enables eps(bool-condition)
Chris@16:     > : is_convertible<A0, bool> {};
Chris@16: 
Chris@16:     template <>                                     // enables eps(f)
Chris@16:     struct use_lazy_terminal<
Chris@16:         qi::domain, tag::eps, 1 /*arity*/
Chris@16:     > : mpl::true_ {};
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::eps;
Chris@16: #endif
Chris@16:     using spirit::eps_type;
Chris@16: 
Chris@16:     struct eps_parser : primitive_parser<eps_parser>
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:         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);
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("eps");
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     struct semantic_predicate : primitive_parser<semantic_predicate>
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:         semantic_predicate(bool predicate_)
Chris@16:           : predicate(predicate_) {}
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);
Chris@16:             return predicate;
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Context>
Chris@16:         info what(Context& /*context*/) const
Chris@16:         {
Chris@16:             return info("semantic-predicate");
Chris@16:         }
Chris@16: 
Chris@16:         bool predicate;
Chris@16:     };
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     // Parser generators: make_xxx function (objects)
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Modifiers>
Chris@16:     struct make_primitive<tag::eps, Modifiers>
Chris@16:     {
Chris@16:         typedef eps_parser result_type;
Chris@16:         result_type operator()(unused_type, unused_type) const
Chris@16:         {
Chris@16:             return result_type();
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Modifiers, typename A0>
Chris@16:     struct make_primitive<
Chris@16:         terminal_ex<tag::eps, fusion::vector1<A0> >
Chris@16:       , Modifiers>
Chris@16:     {
Chris@16:         typedef semantic_predicate result_type;
Chris@16:         template <typename Terminal>
Chris@16:         result_type operator()(Terminal const& term, unused_type) const
Chris@16:         {
Chris@16:             return result_type(fusion::at_c<0>(term.args) ? true : false);
Chris@16:         }
Chris@16:     };
Chris@16: }}}
Chris@16: 
Chris@16: #endif