geometry/core/topological_dimension.hpp

0001 // Boost.Geometry (aka GGL, Generic Geometry Library)
0002
0003 // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
0004 // Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
0005 // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
0006 // Copyright (c) 2024 Adam Wulkiewicz, Lodz, Poland.
0007
0008 // This file was modified by Oracle on 2020-2022.
0009 // Modifications copyright (c) 2020-2022, Oracle and/or its affiliates.
0010 // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
0011
0012 // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
0013 // (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
0014
0015 // Use, modification and distribution is subject to the Boost Software License,
0016 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0017 // http://www.boost.org/LICENSE_1_0.txt)
0018
0019
0020 #ifndef BOOST_GEOMETRY_CORE_TOPOLOGICAL_DIMENSION_HPP
0021 #define BOOST_GEOMETRY_CORE_TOPOLOGICAL_DIMENSION_HPP
0022
0023
0024 #include <type_traits>
0025
0026 #include <boost/geometry/core/tag.hpp>
0027 #include <boost/geometry/core/tags.hpp>
0028
0029
0030 namespace boost { namespace geometry
0031 {
0032
0033
0034 #ifndef DOXYGEN_NO_DISPATCH
0035 namespace core_dispatch
0036 {
0037
0038
0039 template <typename GeometryTag>
0040 struct top_dim {};
0041
0042
0043 template <>
0044 struct top_dim<point_tag>      : std::integral_constant<int, 0> {};
0045
0046
0047 template <>
0048 struct top_dim<linestring_tag> : std::integral_constant<int, 1> {};
0049
0050
0051 template <>
0052 struct top_dim<segment_tag>    : std::integral_constant<int, 1> {};
0053
0054
0055 // ring: topological dimension of two, but some people say: 1 !!
0056 // NOTE: This is not OGC LinearRing!
0057 template <>
0058 struct top_dim<ring_tag>       : std::integral_constant<int, 2> {};
0059
0060
0061 // TODO: This is wrong! Boxes may have various topological dimensions
0062 template <>
0063 struct top_dim<box_tag>        : std::integral_constant<int, 2> {};
0064
0065
0066 template <>
0067 struct top_dim<polygon_tag>    : std::integral_constant<int, 2> {};
0068
0069
0070 template <>
0071 struct top_dim<multi_point_tag> : std::integral_constant<int, 0> {};
0072
0073
0074 template <>
0075 struct top_dim<multi_linestring_tag> : std::integral_constant<int, 1> {};
0076
0077
0078 template <>
0079 struct top_dim<multi_polygon_tag> : std::integral_constant<int, 2> {};
0080
0081
0082 template <>
0083 struct top_dim<geometry_collection_tag> : std::integral_constant<int, -1> {};
0084
0085
0086 } // namespace core_dispatch
0087 #endif
0088
0089
0090
0091
0092
0093 /*!
0094     \brief Meta-function returning the topological dimension of a geometry
0095     \details The topological dimension defines a point as 0-dimensional,
0096         a linestring as 1-dimensional,
0097         and a ring or polygon as 2-dimensional.
0098     \see http://www.math.okstate.edu/mathdept/dynamics/lecnotes/node36.html
0099     \ingroup core
0100 */
0101 template <typename Geometry>
0102 struct topological_dimension
0103     : core_dispatch::top_dim<tag_t<Geometry>> {};
0104
0105
0106 #ifndef BOOST_NO_CXX17_INLINE_VARIABLES
0107 template <typename Geometry>
0108 inline constexpr int topological_dimension_v = topological_dimension<Geometry>::value;
0109 #endif
0110
0111
0112 }} // namespace boost::geometry
0113
0114
0115 #endif // BOOST_GEOMETRY_CORE_TOPOLOGICAL_DIMENSION_HPP