Chris@102: /*=============================================================================
Chris@102:     Copyright (c) 2001-2014 Joel de Guzman
Chris@102: 
Chris@102:     Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@102:     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@102: =============================================================================*/
Chris@102: #if !defined(SPIRIT_DIFFERENCE_FEBRUARY_11_2007_1250PM)
Chris@102: #define SPIRIT_DIFFERENCE_FEBRUARY_11_2007_1250PM
Chris@102: 
Chris@102: #if defined(_MSC_VER)
Chris@102: #pragma once
Chris@102: #endif
Chris@102: 
Chris@102: #include <boost/spirit/home/x3/support/traits/attribute_of.hpp>
Chris@102: #include <boost/spirit/home/x3/support/traits/has_attribute.hpp>
Chris@102: #include <boost/spirit/home/x3/core/parser.hpp>
Chris@102: 
Chris@102: namespace boost { namespace spirit { namespace x3
Chris@102: {
Chris@102:     template <typename Left, typename Right>
Chris@102:     struct difference : binary_parser<Left, Right, difference<Left, Right>>
Chris@102:     {
Chris@102:         typedef binary_parser<Left, Right, difference<Left, Right>> base_type;
Chris@102:         static bool const handles_container = Left::handles_container;
Chris@102: 
Chris@102:         difference(Left const& left, Right const& right)
Chris@102:           : base_type(left, right) {}
Chris@102: 
Chris@102:         template <typename Iterator, typename Context
Chris@102:           , typename RContext, typename Attribute>
Chris@102:         bool parse(Iterator& first, Iterator const& last
Chris@102:           , Context const& context, RContext& rcontext, Attribute& attr) const
Chris@102:         {
Chris@102:             // Try Right first
Chris@102:             Iterator start = first;
Chris@102:             if (this->right.parse(first, last, context, rcontext, unused))
Chris@102:             {
Chris@102:                 // Right succeeds, we fail.
Chris@102:                 first = start;
Chris@102:                 return false;
Chris@102:             }
Chris@102:             // Right fails, now try Left
Chris@102:             return this->left.parse(first, last, context, rcontext, attr);
Chris@102:         }
Chris@102: 
Chris@102:         template <typename Left_, typename Right_>
Chris@102:         difference<Left_, Right_>
Chris@102:         make(Left_ const& left, Right_ const& right) const
Chris@102:         {
Chris@102:             return difference<Left_, Right_>(left, right);
Chris@102:         }
Chris@102:     };
Chris@102: 
Chris@102:     template <typename Left, typename Right>
Chris@102:     inline difference<
Chris@102:         typename extension::as_parser<Left>::value_type
Chris@102:       , typename extension::as_parser<Right>::value_type>
Chris@102:     operator-(Left const& left, Right const& right)
Chris@102:     {
Chris@102:         return {as_parser(left), as_parser(right)};
Chris@102:     }
Chris@102: }}}
Chris@102: 
Chris@102: namespace boost { namespace spirit { namespace x3 { namespace traits
Chris@102: {
Chris@102:     template <typename Left, typename Right, typename Context>
Chris@102:     struct attribute_of<x3::difference<Left, Right>, Context>
Chris@102:         : attribute_of<Left, Context> {};
Chris@102: 
Chris@102:     template <typename Left, typename Right, typename Context>
Chris@102:     struct has_attribute<x3::difference<Left, Right>, Context>
Chris@102:         : has_attribute<Left, Context> {};
Chris@102: }}}}
Chris@102: 
Chris@102: #endif