1/*=============================================================================
2 Copyright (c) 1998-2003 Joel de Guzman
3 Copyright (c) 2001 Daniel Nuffer
4 Copyright (c) 2002 Hartmut Kaiser
5 http://spirit.sourceforge.net/
6
7 Distributed under the Boost Software License, Version 1.0. (See accompanying
8 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9=============================================================================*/
10#if !defined(BOOST_SPIRIT_DIFFERENCE_HPP)
11#define BOOST_SPIRIT_DIFFERENCE_HPP
12
13#include <boost/spirit/home/classic/namespace.hpp>
14#include <boost/spirit/home/classic/core/parser.hpp>
15#include <boost/spirit/home/classic/core/primitives/primitives.hpp>
16#include <boost/spirit/home/classic/core/composite/composite.hpp>
17#include <boost/spirit/home/classic/meta/as_parser.hpp>
18
19namespace boost { namespace spirit {
20
21BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
22
23 ///////////////////////////////////////////////////////////////////////////
24 //
25 // difference: a - b; Matches a but not b
26 //
27 // Handles expressions of the form:
28 //
29 // a - b
30 //
31 // where a and b are parsers. The expression returns a composite
32 // parser that matches a but not b. One (not both) of the operands
33 // may be a literal char, wchar_t or a primitive string char const*,
34 // wchar_t const*.
35 //
36 ///////////////////////////////////////////////////////////////////////////
37 struct difference_parser_gen;
38
39#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
40#pragma warning(push)
41#pragma warning(disable:4512) //assignment operator could not be generated
42#endif
43
44 template <typename A, typename B>
45 struct difference
46 : public binary<A, B, parser<difference<A, B> > >
47 {
48 typedef difference<A, B> self_t;
49 typedef binary_parser_category parser_category_t;
50 typedef difference_parser_gen parser_generator_t;
51 typedef binary<A, B, parser<self_t> > base_t;
52
53 difference(A const& a, B const& b)
54 : base_t(a, b) {}
55
56 template <typename ScannerT>
57 typename parser_result<self_t, ScannerT>::type
58 parse(ScannerT const& scan) const
59 {
60 typedef typename parser_result<self_t, ScannerT>::type result_t;
61 typedef typename ScannerT::iterator_t iterator_t;
62 iterator_t save = scan.first;
63 if (result_t hl = this->left().parse(scan))
64 {
65 std::swap(save, scan.first);
66 result_t hr = this->right().parse(scan);
67 if (!hr || (hr.length() < hl.length()))
68 {
69 scan.first = save;
70 return hl;
71 }
72 }
73
74 return scan.no_match();
75 }
76 };
77
78#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
79#pragma warning(pop)
80#endif
81
82 struct difference_parser_gen
83 {
84 template <typename A, typename B>
85 struct result
86 {
87 typedef
88 difference<
89 typename as_parser<A>::type
90 , typename as_parser<B>::type
91 >
92 type;
93 };
94
95 template <typename A, typename B>
96 static difference<
97 typename as_parser<A>::type
98 , typename as_parser<B>::type
99 >
100 generate(A const& a, B const& b)
101 {
102 return difference<BOOST_DEDUCED_TYPENAME as_parser<A>::type,
103 BOOST_DEDUCED_TYPENAME as_parser<B>::type>
104 (as_parser<A>::convert(a), as_parser<B>::convert(b));
105 }
106 };
107
108 template <typename A, typename B>
109 difference<A, B>
110 operator-(parser<A> const& a, parser<B> const& b);
111
112 template <typename A>
113 difference<A, chlit<char> >
114 operator-(parser<A> const& a, char b);
115
116 template <typename B>
117 difference<chlit<char>, B>
118 operator-(char a, parser<B> const& b);
119
120 template <typename A>
121 difference<A, strlit<char const*> >
122 operator-(parser<A> const& a, char const* b);
123
124 template <typename B>
125 difference<strlit<char const*>, B>
126 operator-(char const* a, parser<B> const& b);
127
128 template <typename A>
129 difference<A, chlit<wchar_t> >
130 operator-(parser<A> const& a, wchar_t b);
131
132 template <typename B>
133 difference<chlit<wchar_t>, B>
134 operator-(wchar_t a, parser<B> const& b);
135
136 template <typename A>
137 difference<A, strlit<wchar_t const*> >
138 operator-(parser<A> const& a, wchar_t const* b);
139
140 template <typename B>
141 difference<strlit<wchar_t const*>, B>
142 operator-(wchar_t const* a, parser<B> const& b);
143
144BOOST_SPIRIT_CLASSIC_NAMESPACE_END
145
146}} // namespace BOOST_SPIRIT_CLASSIC_NS
147
148#endif
149
150#include <boost/spirit/home/classic/core/composite/impl/difference.ipp>
151

source code of boost/libs/spirit/include/boost/spirit/home/classic/core/composite/difference.hpp