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1 | /////////////////////////////////////////////////////////////////////////////// |
2 | // optional_matcher.hpp | |
3 | // | |
4 | // Copyright 2008 Eric Niebler. Distributed under the Boost | |
5 | // Software License, Version 1.0. (See accompanying file | |
6 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
7 | ||
8 | #ifndef BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_OPTIONAL_MATCHER_HPP_EAN_10_04_2005 | |
9 | #define BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_OPTIONAL_MATCHER_HPP_EAN_10_04_2005 | |
10 | ||
11 | // MS compatible compilers support #pragma once | |
12 | #if defined(_MSC_VER) | |
13 | # pragma once | |
14 | #endif | |
15 | ||
16 | #include <boost/mpl/bool.hpp> | |
17 | #include <boost/xpressive/detail/detail_fwd.hpp> | |
18 | #include <boost/xpressive/detail/core/quant_style.hpp> | |
19 | #include <boost/xpressive/detail/core/state.hpp> | |
20 | ||
21 | namespace boost { namespace xpressive { namespace detail | |
22 | { | |
23 | ||
24 | /////////////////////////////////////////////////////////////////////////////// | |
25 | // optional_matcher | |
26 | template<typename Xpr, typename Greedy> | |
27 | struct optional_matcher | |
28 | : quant_style<quant_variable_width, unknown_width::value, Xpr::pure> | |
29 | { | |
30 | Xpr xpr_; | |
31 | ||
32 | explicit optional_matcher(Xpr const &xpr) | |
33 | : xpr_(xpr) | |
34 | { | |
35 | } | |
36 | ||
37 | template<typename BidiIter, typename Next> | |
38 | bool match(match_state<BidiIter> &state, Next const &next) const | |
39 | { | |
40 | return this->match_(state, next, Greedy()); | |
41 | } | |
42 | ||
43 | private: | |
44 | template<typename BidiIter, typename Next> | |
45 | bool match_(match_state<BidiIter> &state, Next const &next, mpl::true_) const // Greedy | |
46 | { | |
47 | return this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state) | |
48 | || next.match(state); | |
49 | } | |
50 | ||
51 | template<typename BidiIter, typename Next> | |
52 | bool match_(match_state<BidiIter> &state, Next const &next, mpl::false_) const // Non-greedy | |
53 | { | |
54 | return next.match(state) | |
55 | || this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state); | |
56 | } | |
57 | ||
58 | optional_matcher &operator =(optional_matcher const &); | |
59 | }; | |
60 | ||
61 | /////////////////////////////////////////////////////////////////////////////// | |
62 | // optional_mark_matcher | |
63 | template<typename BidiIter, typename Next> | |
64 | inline bool match_next(match_state<BidiIter> &state, Next const &next, int mark_number) | |
65 | { | |
66 | sub_match_impl<BidiIter> &br = state.sub_match(mark_number); | |
67 | ||
68 | bool old_matched = br.matched; | |
69 | br.matched = false; | |
70 | ||
71 | if(next.match(state)) | |
72 | { | |
73 | return true; | |
74 | } | |
75 | ||
76 | br.matched = old_matched; | |
77 | return false; | |
78 | } | |
79 | ||
80 | /////////////////////////////////////////////////////////////////////////////// | |
81 | // optional_mark_matcher | |
82 | template<typename Xpr, typename Greedy> | |
83 | struct optional_mark_matcher | |
84 | : quant_style<quant_variable_width, unknown_width::value, Xpr::pure> | |
85 | { | |
86 | Xpr xpr_; | |
87 | int mark_number_; | |
88 | ||
89 | explicit optional_mark_matcher(Xpr const &xpr, int mark_number) | |
90 | : xpr_(xpr) | |
91 | , mark_number_(mark_number) | |
92 | { | |
93 | } | |
94 | ||
95 | template<typename BidiIter, typename Next> | |
96 | bool match(match_state<BidiIter> &state, Next const &next) const | |
97 | { | |
98 | return this->match_(state, next, Greedy()); | |
99 | } | |
100 | ||
101 | private: | |
102 | template<typename BidiIter, typename Next> | |
103 | bool match_(match_state<BidiIter> &state, Next const &next, mpl::true_) const // Greedy | |
104 | { | |
105 | return this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state) | |
106 | || match_next(state, next, this->mark_number_); | |
107 | } | |
108 | ||
109 | template<typename BidiIter, typename Next> | |
110 | bool match_(match_state<BidiIter> &state, Next const &next, mpl::false_) const // Non-greedy | |
111 | { | |
112 | return match_next(state, next, this->mark_number_) | |
113 | || this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state); | |
114 | } | |
115 | ||
116 | optional_mark_matcher &operator =(optional_mark_matcher const &); | |
117 | }; | |
118 | ||
119 | }}} | |
120 | ||
121 | #endif |