| /*============================================================================= |
| Copyright (c) 2001-2014 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/x3/support/traits/attribute_of.hpp> |
| #include <boost/spirit/home/x3/support/traits/has_attribute.hpp> |
| #include <boost/spirit/home/x3/core/parser.hpp> |
| |
| namespace boost { namespace spirit { namespace x3 |
| { |
| template <typename Left, typename Right> |
| struct difference : binary_parser<Left, Right, difference<Left, Right>> |
| { |
| typedef binary_parser<Left, Right, difference<Left, Right>> base_type; |
| static bool const handles_container = Left::handles_container; |
| |
| difference(Left const& left, Right const& right) |
| : base_type(left, right) {} |
| |
| template <typename Iterator, typename Context |
| , typename RContext, typename Attribute> |
| bool parse(Iterator& first, Iterator const& last |
| , Context const& context, RContext& rcontext, Attribute& attr) const |
| { |
| // Try Right first |
| Iterator start = first; |
| if (this->right.parse(first, last, context, rcontext, unused)) |
| { |
| // Right succeeds, we fail. |
| first = start; |
| return false; |
| } |
| // Right fails, now try Left |
| return this->left.parse(first, last, context, rcontext, attr); |
| } |
| |
| template <typename Left_, typename Right_> |
| difference<Left_, Right_> |
| make(Left_ const& left, Right_ const& right) const |
| { |
| return difference<Left_, Right_>(left, right); |
| } |
| }; |
| |
| template <typename Left, typename Right> |
| inline difference< |
| typename extension::as_parser<Left>::value_type |
| , typename extension::as_parser<Right>::value_type> |
| operator-(Left const& left, Right const& right) |
| { |
| return {as_parser(left), as_parser(right)}; |
| } |
| }}} |
| |
| namespace boost { namespace spirit { namespace x3 { namespace traits |
| { |
| template <typename Left, typename Right, typename Context> |
| struct attribute_of<x3::difference<Left, Right>, Context> |
| : attribute_of<Left, Context> {}; |
| |
| template <typename Left, typename Right, typename Context> |
| struct has_attribute<x3::difference<Left, Right>, Context> |
| : has_attribute<Left, Context> {}; |
| }}}} |
| |
| #endif |