geometry/algorithms/is_empty.hpp

0001 // Boost.Geometry (aka GGL, Generic Geometry Library)
0002
0003 // Copyright (c) 2015-2023, Oracle and/or its affiliates.
0004
0005 // Contributed and/or modified by Vissarion Fysikopoulos, on behalf of Oracle
0006 // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
0007 // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
0008
0009 // Licensed under the Boost Software License version 1.0.
0010 // http://www.boost.org/users/license.html
0011
0012 #ifndef BOOST_GEOMETRY_ALGORITHMS_IS_EMPTY_HPP
0013 #define BOOST_GEOMETRY_ALGORITHMS_IS_EMPTY_HPP
0014
0015 #include <boost/range/begin.hpp>
0016 #include <boost/range/empty.hpp>
0017 #include <boost/range/end.hpp>
0018
0019 #include <boost/geometry/algorithms/not_implemented.hpp>
0020 #include <boost/geometry/algorithms/detail/visit.hpp>
0021
0022 #include <boost/geometry/core/exterior_ring.hpp>
0023 #include <boost/geometry/core/interior_rings.hpp>
0024 #include <boost/geometry/core/tag.hpp>
0025 #include <boost/geometry/core/tags.hpp>
0026 #include <boost/geometry/core/visit.hpp>
0027
0028 #include <boost/geometry/geometries/adapted/boost_variant.hpp> // For backward compatibility
0029 #include <boost/geometry/geometries/concepts/check.hpp>
0030
0031 #include <boost/geometry/util/type_traits_std.hpp>
0032
0033 namespace boost { namespace geometry
0034 {
0035
0036
0037 #ifndef DOXYGEN_NO_DETAIL
0038 namespace detail { namespace is_empty
0039 {
0040
0041 struct always_not_empty
0042 {
0043     template <typename Geometry>
0044     static inline bool apply(Geometry const&)
0045     {
0046         return false;
0047     }
0048 };
0049
0050 struct range_is_empty
0051 {
0052     template <typename Range>
0053     static inline bool apply(Range const& range)
0054     {
0055         return boost::empty(range);
0056     }
0057 };
0058
0059 class polygon_is_empty
0060 {
0061     template <typename InteriorRings>
0062     static inline bool check_interior_rings(InteriorRings const& interior_rings)
0063     {
0064         return std::all_of(boost::begin(interior_rings), boost::end(interior_rings),
0065                            []( auto const& range ){ return boost::empty(range); });
0066     }
0067
0068 public:
0069     template <typename Polygon>
0070     static inline bool apply(Polygon const& polygon)
0071     {
0072         return boost::empty(exterior_ring(polygon))
0073             && check_interior_rings(interior_rings(polygon));
0074     }
0075 };
0076
0077 template <typename Policy = range_is_empty>
0078 struct multi_is_empty
0079 {
0080     template <typename MultiGeometry>
0081     static inline bool apply(MultiGeometry const& multigeometry)
0082     {
0083         return std::all_of(boost::begin(multigeometry),
0084                            boost::end(multigeometry),
0085                            []( auto const& range ){ return Policy::apply(range); });
0086     }
0087 };
0088
0089 }} // namespace detail::is_empty
0090 #endif // DOXYGEN_NO_DETAIL
0091
0092
0093 #ifndef DOXYGEN_NO_DISPATCH
0094 namespace dispatch
0095 {
0096
0097 template <typename Geometry, typename Tag =  tag_t<Geometry>>
0098 struct is_empty : not_implemented<Tag>
0099 {};
0100
0101 template <typename Geometry>
0102 struct is_empty<Geometry, point_tag>
0103     : detail::is_empty::always_not_empty
0104 {};
0105
0106 template <typename Geometry>
0107 struct is_empty<Geometry, box_tag>
0108     : detail::is_empty::always_not_empty
0109 {};
0110
0111 template <typename Geometry>
0112 struct is_empty<Geometry, segment_tag>
0113     : detail::is_empty::always_not_empty
0114 {};
0115
0116 template <typename Geometry>
0117 struct is_empty<Geometry, linestring_tag>
0118     : detail::is_empty::range_is_empty
0119 {};
0120
0121 template <typename Geometry>
0122 struct is_empty<Geometry, ring_tag>
0123     : detail::is_empty::range_is_empty
0124 {};
0125
0126 template <typename Geometry>
0127 struct is_empty<Geometry, polygon_tag>
0128     : detail::is_empty::polygon_is_empty
0129 {};
0130
0131 template <typename Geometry>
0132 struct is_empty<Geometry, multi_point_tag>
0133     : detail::is_empty::range_is_empty
0134 {};
0135
0136 template <typename Geometry>
0137 struct is_empty<Geometry, multi_linestring_tag>
0138     : detail::is_empty::multi_is_empty<>
0139 {};
0140
0141 template <typename Geometry>
0142 struct is_empty<Geometry, multi_polygon_tag>
0143     : detail::is_empty::multi_is_empty<detail::is_empty::polygon_is_empty>
0144 {};
0145
0146 } // namespace dispatch
0147 #endif // DOXYGEN_NO_DISPATCH
0148
0149
0150 namespace resolve_dynamic
0151 {
0152
0153 template <typename Geometry, typename Tag = tag_t<Geometry>>
0154 struct is_empty
0155 {
0156     static inline bool apply(Geometry const& geometry)
0157     {
0158         concepts::check<Geometry const>();
0159
0160         return dispatch::is_empty<Geometry>::apply(geometry);
0161     }
0162 };
0163
0164 template <typename Geometry>
0165 struct is_empty<Geometry, dynamic_geometry_tag>
0166 {
0167     static inline bool apply(Geometry const& geometry)
0168     {
0169         bool result = true;
0170         traits::visit<Geometry>::apply([&](auto const& g)
0171         {
0172             result = is_empty<util::remove_cref_t<decltype(g)>>::apply(g);
0173         }, geometry);
0174         return result;
0175     }
0176 };
0177
0178 template <typename Geometry>
0179 struct is_empty<Geometry, geometry_collection_tag>
0180 {
0181     static inline bool apply(Geometry const& geometry)
0182     {
0183         bool result = true;
0184         detail::visit_breadth_first([&](auto const& g)
0185         {
0186             result = is_empty<util::remove_cref_t<decltype(g)>>::apply(g);
0187             return result;
0188         }, geometry);
0189         return result;
0190     }
0191 };
0192
0193 } // namespace resolve_dynamic
0194
0195
0196 /*!
0197 \brief \brief_check{is the empty set}
0198 \ingroup is_empty
0199 \tparam Geometry \tparam_geometry
0200 \param geometry \param_geometry
0201 \return \return_check{is the empty set}
0202
0203 \qbk{[include reference/algorithms/is_empty.qbk]}
0204 */
0205 template <typename Geometry>
0206 inline bool is_empty(Geometry const& geometry)
0207 {
0208     return resolve_dynamic::is_empty<Geometry>::apply(geometry);
0209 }
0210
0211
0212 }} // namespace boost::geometry
0213
0214
0215 #endif // BOOST_GEOMETRY_ALGORITHMS_IS_EMPTY_HPP