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 
19 namespace boost { namespace spirit {
20 
21 BOOST_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 
differenceboost::spirit::difference53         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
parseboost::spirit::difference58         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         >
generateboost::spirit::difference_parser_gen100         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 
144 BOOST_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