1/*=============================================================================
2 Copyright (c) 2001-2014 Joel de Guzman
3
4 Distributed under the Boost Software License, Version 1.0. (See accompanying
5 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6=============================================================================*/
7#if !defined(BOOST_SPIRIT_X3_DIFFERENCE_FEBRUARY_11_2007_1250PM)
8#define BOOST_SPIRIT_X3_DIFFERENCE_FEBRUARY_11_2007_1250PM
9
10#include <boost/spirit/home/x3/support/traits/attribute_of.hpp>
11#include <boost/spirit/home/x3/support/traits/has_attribute.hpp>
12#include <boost/spirit/home/x3/core/parser.hpp>
13
14namespace boost { namespace spirit { namespace x3
15{
16 template <typename Left, typename Right>
17 struct difference : binary_parser<Left, Right, difference<Left, Right>>
18 {
19 typedef binary_parser<Left, Right, difference<Left, Right>> base_type;
20 static bool const handles_container = Left::handles_container;
21
22 constexpr difference(Left const& left, Right const& right)
23 : base_type(left, right) {}
24
25 template <typename Iterator, typename Context
26 , typename RContext, typename Attribute>
27 bool parse(Iterator& first, Iterator const& last
28 , Context const& context, RContext& rcontext, Attribute& attr) const
29 {
30 // Try Right first
31 Iterator start = first;
32 if (this->right.parse(first, last, context, rcontext, unused))
33 {
34 // Right succeeds, we fail.
35 first = start;
36 return false;
37 }
38 // Right fails, now try Left
39 return this->left.parse(first, last, context, rcontext, attr);
40 }
41
42 template <typename Left_, typename Right_>
43 constexpr difference<Left_, Right_>
44 make(Left_ const& left, Right_ const& right) const
45 {
46 return { left, right };
47 }
48 };
49
50 template <typename Left, typename Right>
51 constexpr difference<
52 typename extension::as_parser<Left>::value_type
53 , typename extension::as_parser<Right>::value_type>
54 operator-(Left const& left, Right const& right)
55 {
56 return { as_parser(left), as_parser(right) };
57 }
58}}}
59
60namespace boost { namespace spirit { namespace x3 { namespace traits
61{
62 template <typename Left, typename Right, typename Context>
63 struct attribute_of<x3::difference<Left, Right>, Context>
64 : attribute_of<Left, Context> {};
65
66 template <typename Left, typename Right, typename Context>
67 struct has_attribute<x3::difference<Left, Right>, Context>
68 : has_attribute<Left, Context> {};
69}}}}
70
71#endif
72

source code of boost/libs/spirit/include/boost/spirit/home/x3/operator/difference.hpp