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1 | // Boost.Geometry (aka GGL, Generic Geometry Library) |
2 | ||
3 | // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands. | |
4 | // Copyright (c) 2008-2012 Bruno Lalande, Paris, France. | |
5 | // Copyright (c) 2009-2012 Mateusz Loskot, London, UK. | |
6 | ||
7 | // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library | |
8 | // (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands. | |
9 | ||
10 | // Use, modification and distribution is subject to the Boost Software License, | |
11 | // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
12 | // http://www.boost.org/LICENSE_1_0.txt) | |
13 | ||
14 | #ifndef BOOST_GEOMETRY_ITERATORS_EVER_CIRCLING_ITERATOR_HPP | |
15 | #define BOOST_GEOMETRY_ITERATORS_EVER_CIRCLING_ITERATOR_HPP | |
16 | ||
17 | #include <boost/range.hpp> | |
18 | #include <boost/iterator.hpp> | |
19 | #include <boost/iterator/iterator_adaptor.hpp> | |
20 | #include <boost/iterator/iterator_categories.hpp> | |
21 | ||
22 | #include <boost/geometry/iterators/base.hpp> | |
23 | ||
24 | namespace boost { namespace geometry | |
25 | { | |
26 | ||
27 | /*! | |
28 | \brief Iterator which ever circles through a range | |
29 | \tparam Iterator iterator on which this class is based on | |
30 | \ingroup iterators | |
31 | \details If the iterator arrives at range.end() it restarts from the | |
32 | beginning. So it has to be stopped in another way. | |
33 | Don't call for(....; it++) because it will turn in an endless loop | |
34 | \note Name inspired on David Bowie's | |
35 | "Chant Of The Ever Circling Skeletal Family" | |
36 | */ | |
37 | template <typename Iterator> | |
38 | struct ever_circling_iterator : | |
39 | public detail::iterators::iterator_base | |
40 | < | |
41 | ever_circling_iterator<Iterator>, | |
42 | Iterator | |
43 | > | |
44 | { | |
45 | friend class boost::iterator_core_access; | |
46 | ||
47 | explicit inline ever_circling_iterator(Iterator begin, Iterator end, | |
48 | bool skip_first = false) | |
49 | : m_begin(begin) | |
50 | , m_end(end) | |
51 | , m_skip_first(skip_first) | |
52 | { | |
53 | this->base_reference() = begin; | |
54 | } | |
55 | ||
56 | explicit inline ever_circling_iterator(Iterator begin, Iterator end, Iterator start, | |
57 | bool skip_first = false) | |
58 | : m_begin(begin) | |
59 | , m_end(end) | |
60 | , m_skip_first(skip_first) | |
61 | { | |
62 | this->base_reference() = start; | |
63 | } | |
64 | ||
65 | /// Navigate to a certain position, should be in [start .. end], if at end | |
66 | /// it will circle again. | |
67 | inline void moveto(Iterator it) | |
68 | { | |
69 | this->base_reference() = it; | |
70 | check_end(); | |
71 | } | |
72 | ||
73 | private: | |
74 | ||
75 | inline void increment(bool possibly_skip = true) | |
76 | { | |
77 | (this->base_reference())++; | |
78 | check_end(possibly_skip); | |
79 | } | |
80 | ||
81 | inline void check_end(bool possibly_skip = true) | |
82 | { | |
83 | if (this->base() == this->m_end) | |
84 | { | |
85 | this->base_reference() = this->m_begin; | |
86 | if (m_skip_first && possibly_skip) | |
87 | { | |
88 | increment(false); | |
89 | } | |
90 | } | |
91 | } | |
92 | ||
93 | Iterator m_begin; | |
94 | Iterator m_end; | |
95 | bool m_skip_first; | |
96 | }; | |
97 | ||
98 | template <typename Range> | |
99 | struct ever_circling_range_iterator | |
100 | : public boost::iterator_facade | |
101 | < | |
102 | ever_circling_range_iterator<Range>, | |
103 | typename boost::range_value<Range>::type const, | |
104 | boost::random_access_traversal_tag | |
105 | > | |
106 | { | |
107 | /// Constructor including the range it is based on | |
108 | explicit inline ever_circling_range_iterator(Range& range) | |
109 | : m_range(&range) | |
110 | , m_iterator(boost::begin(range)) | |
111 | , m_size(boost::size(range)) | |
112 | , m_index(0) | |
113 | {} | |
114 | ||
115 | /// Default constructor | |
116 | explicit inline ever_circling_range_iterator() | |
117 | : m_range(NULL) | |
118 | , m_size(0) | |
119 | , m_index(0) | |
120 | {} | |
121 | ||
122 | typedef std::ptrdiff_t difference_type; | |
123 | ||
124 | private: | |
125 | friend class boost::iterator_core_access; | |
126 | ||
127 | inline typename boost::range_value<Range>::type const& dereference() const | |
128 | { | |
129 | return *m_iterator; | |
130 | } | |
131 | ||
132 | inline difference_type distance_to(ever_circling_range_iterator<Range> const& other) const | |
133 | { | |
134 | return other.m_index - this->m_index; | |
135 | } | |
136 | ||
137 | inline bool equal(ever_circling_range_iterator<Range> const& other) const | |
138 | { | |
139 | return this->m_range == other.m_range | |
140 | && this->m_index == other.m_index; | |
141 | } | |
142 | ||
143 | inline void increment() | |
144 | { | |
145 | ++m_index; | |
146 | if (m_index >= 0 && m_index < m_size) | |
147 | { | |
148 | ++m_iterator; | |
149 | } | |
150 | else | |
151 | { | |
152 | update_iterator(); | |
153 | } | |
154 | } | |
155 | ||
156 | inline void decrement() | |
157 | { | |
158 | --m_index; | |
159 | if (m_index >= 0 && m_index < m_size) | |
160 | { | |
161 | --m_iterator; | |
162 | } | |
163 | else | |
164 | { | |
165 | update_iterator(); | |
166 | } | |
167 | } | |
168 | ||
169 | inline void advance(difference_type n) | |
170 | { | |
171 | if (m_index >= 0 && m_index < m_size | |
172 | && m_index + n >= 0 && m_index + n < m_size) | |
173 | { | |
174 | m_index += n; | |
175 | m_iterator += n; | |
176 | } | |
177 | else | |
178 | { | |
179 | m_index += n; | |
180 | update_iterator(); | |
181 | } | |
182 | } | |
183 | ||
184 | inline void update_iterator() | |
185 | { | |
186 | while (m_index < 0) | |
187 | { | |
188 | m_index += m_size; | |
189 | } | |
190 | m_index = m_index % m_size; | |
191 | this->m_iterator = boost::begin(*m_range) + m_index; | |
192 | } | |
193 | ||
194 | Range* m_range; | |
195 | typename boost::range_iterator<Range>::type m_iterator; | |
196 | difference_type m_size; | |
197 | difference_type m_index; | |
198 | }; | |
199 | ||
200 | ||
201 | }} // namespace boost::geometry | |
202 | ||
203 | #endif // BOOST_GEOMETRY_ITERATORS_EVER_CIRCLING_ITERATOR_HPP |