/*============================================================================= | |
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(SPIRIT_DIFFERENCE_FEBRUARY_11_2007_1250PM) | |
#define SPIRIT_DIFFERENCE_FEBRUARY_11_2007_1250PM | |
#if defined(_MSC_VER) | |
#pragma once | |
#endif | |
#include <boost/spirit/home/qi/domain.hpp> | |
#include <boost/spirit/home/qi/meta_compiler.hpp> | |
#include <boost/spirit/home/qi/parser.hpp> | |
#include <boost/spirit/home/qi/detail/attributes.hpp> | |
#include <boost/spirit/home/support/info.hpp> | |
#include <boost/spirit/home/support/has_semantic_action.hpp> | |
#include <boost/spirit/home/support/handles_container.hpp> | |
#include <boost/fusion/include/at.hpp> | |
namespace boost { namespace spirit | |
{ | |
/////////////////////////////////////////////////////////////////////////// | |
// Enablers | |
/////////////////////////////////////////////////////////////////////////// | |
template <> | |
struct use_operator<qi::domain, proto::tag::minus> // enables - | |
: mpl::true_ {}; | |
}} | |
namespace boost { namespace spirit { namespace qi | |
{ | |
template <typename Left, typename Right> | |
struct difference : binary_parser<difference<Left, Right> > | |
{ | |
typedef Left left_type; | |
typedef Right right_type; | |
template <typename Context, typename Iterator> | |
struct attribute | |
{ | |
typedef typename | |
traits::attribute_of<left_type, Context, Iterator>::type | |
type; | |
}; | |
difference(Left const& left, Right const& right) | |
: left(left), right(right) {} | |
template <typename Iterator, typename Context | |
, typename Skipper, typename Attribute> | |
bool parse(Iterator& first, Iterator const& last | |
, Context& context, Skipper const& skipper | |
, Attribute& attr) const | |
{ | |
// Unlike classic Spirit, with this version of difference, the rule | |
// lit("policeman") - "police" will always fail to match. | |
// Spirit2 does not count the matching chars while parsing and | |
// there is no reliable and fast way to check if the LHS matches | |
// more than the RHS. | |
// Try RHS first | |
Iterator start = first; | |
if (right.parse(first, last, context, skipper, unused)) | |
{ | |
// RHS succeeds, we fail. | |
first = start; | |
return false; | |
} | |
// RHS fails, now try LHS | |
return left.parse(first, last, context, skipper, attr); | |
} | |
template <typename Context> | |
info what(Context& context) const | |
{ | |
return info("difference", | |
std::make_pair(left.what(context), right.what(context))); | |
} | |
Left left; | |
Right right; | |
}; | |
/////////////////////////////////////////////////////////////////////////// | |
// Parser generators: make_xxx function (objects) | |
/////////////////////////////////////////////////////////////////////////// | |
template <typename Elements, typename Modifiers> | |
struct make_composite<proto::tag::minus, Elements, Modifiers> | |
: make_binary_composite<Elements, difference> | |
{}; | |
}}} | |
namespace boost { namespace spirit { namespace traits | |
{ | |
/////////////////////////////////////////////////////////////////////////// | |
template <typename Left, typename Right> | |
struct has_semantic_action<qi::difference<Left, Right> > | |
: binary_has_semantic_action<Left, Right> {}; | |
/////////////////////////////////////////////////////////////////////////// | |
template <typename Left, typename Right, typename Attribute | |
, typename Context, typename Iterator> | |
struct handles_container<qi::difference<Left, Right>, Attribute, Context | |
, Iterator> | |
: binary_handles_container<Left, Right, Attribute, Context, Iterator> {}; | |
}}} | |
#endif |