/*============================================================================= | |
Copyright (c) 2001-2011 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 |