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7c673cae FG |
1 | // Boost.Geometry (aka GGL, Generic Geometry Library) |
2 | ||
20effc67 | 3 | // Copyright (c) 2015-2020, Oracle and/or its affiliates. |
7c673cae FG |
4 | |
5 | // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle | |
20effc67 | 6 | // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle |
7c673cae FG |
7 | |
8 | // Licensed under the Boost Software License version 1.0. | |
9 | // http://www.boost.org/users/license.html | |
10 | ||
11 | #ifndef BOOST_GEOMETRY_ALGORITHMS_IS_EMPTY_HPP | |
12 | #define BOOST_GEOMETRY_ALGORITHMS_IS_EMPTY_HPP | |
13 | ||
20effc67 TL |
14 | #include <boost/range/begin.hpp> |
15 | #include <boost/range/empty.hpp> | |
16 | #include <boost/range/end.hpp> | |
7c673cae FG |
17 | |
18 | #include <boost/variant/apply_visitor.hpp> | |
19 | #include <boost/variant/static_visitor.hpp> | |
20 | #include <boost/variant/variant_fwd.hpp> | |
21 | ||
22 | #include <boost/geometry/core/exterior_ring.hpp> | |
23 | #include <boost/geometry/core/interior_rings.hpp> | |
24 | #include <boost/geometry/core/tag.hpp> | |
25 | #include <boost/geometry/core/tags.hpp> | |
26 | ||
27 | #include <boost/geometry/algorithms/not_implemented.hpp> | |
28 | ||
29 | #include <boost/geometry/algorithms/detail/check_iterator_range.hpp> | |
30 | ||
31 | #include <boost/geometry/geometries/concepts/check.hpp> | |
32 | ||
33 | ||
34 | namespace boost { namespace geometry | |
35 | { | |
36 | ||
37 | ||
38 | #ifndef DOXYGEN_NO_DETAIL | |
39 | namespace detail { namespace is_empty | |
40 | { | |
41 | ||
42 | struct always_not_empty | |
43 | { | |
44 | template <typename Geometry> | |
45 | static inline bool apply(Geometry const&) | |
46 | { | |
47 | return false; | |
48 | } | |
49 | }; | |
50 | ||
51 | struct range_is_empty | |
52 | { | |
53 | template <typename Range> | |
54 | static inline bool apply(Range const& range) | |
55 | { | |
56 | return boost::empty(range); | |
57 | } | |
58 | }; | |
59 | ||
60 | class polygon_is_empty | |
61 | { | |
62 | template <typename InteriorRings> | |
63 | static inline bool check_interior_rings(InteriorRings const& interior_rings) | |
64 | { | |
65 | return check_iterator_range | |
66 | < | |
67 | range_is_empty, true // allow empty range | |
68 | >::apply(boost::begin(interior_rings), boost::end(interior_rings)); | |
69 | } | |
70 | ||
71 | public: | |
72 | template <typename Polygon> | |
73 | static inline bool apply(Polygon const& polygon) | |
74 | { | |
75 | return boost::empty(exterior_ring(polygon)) | |
76 | && check_interior_rings(interior_rings(polygon)); | |
77 | } | |
78 | }; | |
79 | ||
80 | template <typename Policy = range_is_empty> | |
81 | struct multi_is_empty | |
82 | { | |
83 | template <typename MultiGeometry> | |
84 | static inline bool apply(MultiGeometry const& multigeometry) | |
85 | { | |
86 | return check_iterator_range | |
87 | < | |
88 | Policy, true // allow empty range | |
89 | >::apply(boost::begin(multigeometry), boost::end(multigeometry)); | |
90 | } | |
91 | ||
92 | }; | |
93 | ||
94 | }} // namespace detail::is_empty | |
95 | #endif // DOXYGEN_NO_DETAIL | |
96 | ||
97 | ||
98 | #ifndef DOXYGEN_NO_DISPATCH | |
99 | namespace dispatch | |
100 | { | |
101 | ||
102 | template <typename Geometry, typename Tag = typename tag<Geometry>::type> | |
103 | struct is_empty : not_implemented<Tag> | |
104 | {}; | |
105 | ||
106 | template <typename Geometry> | |
107 | struct is_empty<Geometry, point_tag> | |
108 | : detail::is_empty::always_not_empty | |
109 | {}; | |
110 | ||
111 | template <typename Geometry> | |
112 | struct is_empty<Geometry, box_tag> | |
113 | : detail::is_empty::always_not_empty | |
114 | {}; | |
115 | ||
116 | template <typename Geometry> | |
117 | struct is_empty<Geometry, segment_tag> | |
118 | : detail::is_empty::always_not_empty | |
119 | {}; | |
120 | ||
121 | template <typename Geometry> | |
122 | struct is_empty<Geometry, linestring_tag> | |
123 | : detail::is_empty::range_is_empty | |
124 | {}; | |
125 | ||
126 | template <typename Geometry> | |
127 | struct is_empty<Geometry, ring_tag> | |
128 | : detail::is_empty::range_is_empty | |
129 | {}; | |
130 | ||
131 | template <typename Geometry> | |
132 | struct is_empty<Geometry, polygon_tag> | |
133 | : detail::is_empty::polygon_is_empty | |
134 | {}; | |
135 | ||
136 | template <typename Geometry> | |
137 | struct is_empty<Geometry, multi_point_tag> | |
138 | : detail::is_empty::range_is_empty | |
139 | {}; | |
140 | ||
141 | template <typename Geometry> | |
142 | struct is_empty<Geometry, multi_linestring_tag> | |
143 | : detail::is_empty::multi_is_empty<> | |
144 | {}; | |
145 | ||
146 | template <typename Geometry> | |
147 | struct is_empty<Geometry, multi_polygon_tag> | |
148 | : detail::is_empty::multi_is_empty<detail::is_empty::polygon_is_empty> | |
149 | {}; | |
150 | ||
151 | } // namespace dispatch | |
152 | #endif // DOXYGEN_NO_DISPATCH | |
153 | ||
154 | ||
155 | namespace resolve_variant | |
156 | { | |
157 | ||
158 | template <typename Geometry> | |
159 | struct is_empty | |
160 | { | |
161 | static inline bool apply(Geometry const& geometry) | |
162 | { | |
163 | concepts::check<Geometry const>(); | |
164 | ||
165 | return dispatch::is_empty<Geometry>::apply(geometry); | |
166 | } | |
167 | }; | |
168 | ||
169 | template <BOOST_VARIANT_ENUM_PARAMS(typename T)> | |
170 | struct is_empty<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> > | |
171 | { | |
172 | struct visitor : boost::static_visitor<bool> | |
173 | { | |
174 | template <typename Geometry> | |
175 | inline bool operator()(Geometry const& geometry) const | |
176 | { | |
177 | return is_empty<Geometry>::apply(geometry); | |
178 | } | |
179 | }; | |
180 | ||
181 | static bool | |
182 | apply(boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const& geometry) | |
183 | { | |
184 | return boost::apply_visitor(visitor(), geometry); | |
185 | } | |
186 | }; | |
187 | ||
188 | } // namespace resolve_variant | |
189 | ||
190 | ||
191 | /*! | |
192 | \brief \brief_check{is the empty set} | |
193 | \ingroup is_empty | |
194 | \tparam Geometry \tparam_geometry | |
195 | \param geometry \param_geometry | |
196 | \return \return_check{is the empty set} | |
197 | ||
198 | \qbk{[include reference/algorithms/is_empty.qbk]} | |
199 | */ | |
200 | template <typename Geometry> | |
201 | inline bool is_empty(Geometry const& geometry) | |
202 | { | |
203 | return resolve_variant::is_empty<Geometry>::apply(geometry); | |
204 | } | |
205 | ||
206 | ||
207 | }} // namespace boost::geometry | |
208 | ||
209 | ||
210 | #endif // BOOST_GEOMETRY_ALGORITHMS_IS_EMPTY_HPP |