ceph/src/boost/boost/geometry/algorithms/detail/overlay/get_ring.hpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2
   3 // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
   4
   5 // Use, modification and distribution is subject to the Boost Software License,
   6 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8
   9 #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_RING_HPP
  10 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_RING_HPP
  11
  12
  13 #include <boost/range.hpp>
  14
  15 #include <boost/geometry/core/assert.hpp>
  16 #include <boost/geometry/core/exterior_ring.hpp>
  17 #include <boost/geometry/core/interior_rings.hpp>
  18 #include <boost/geometry/core/ring_type.hpp>
  19 #include <boost/geometry/core/tags.hpp>
  20 #include <boost/geometry/algorithms/detail/ring_identifier.hpp>
  21 #include <boost/geometry/algorithms/detail/overlay/segment_identifier.hpp>
  22 #include <boost/geometry/algorithms/num_points.hpp>
  23 #include <boost/geometry/geometries/concepts/check.hpp>
  24 #include <boost/geometry/util/range.hpp>
  25
  26
  27 namespace boost { namespace geometry
  28 {
  29
  30
  31 #ifndef DOXYGEN_NO_DETAIL
  32 namespace detail { namespace overlay
  33 {
  34
  35
  36 template<typename Tag>
  37 struct get_ring
  38 {};
  39
  40 // A range of rings (multi-ring but that does not exist)
  41 // gets the "void" tag and is dispatched here.
  42 template<>
  43 struct get_ring<void>
  44 {
  45     template<typename Range>
  46     static inline typename boost::range_value<Range>::type const&
  47                 apply(ring_identifier const& id, Range const& container)
  48     {
  49         return range::at(container, id.multi_index);
  50     }
  51 };
  52
  53
  54 template<>
  55 struct get_ring<ring_tag>
  56 {
  57     template<typename Ring>
  58     static inline Ring const& apply(ring_identifier const& , Ring const& ring)
  59     {
  60         return ring;
  61     }
  62 };
  63
  64
  65 template<>
  66 struct get_ring<box_tag>
  67 {
  68     template<typename Box>
  69     static inline Box const& apply(ring_identifier const& ,
  70                     Box const& box)
  71     {
  72         return box;
  73     }
  74 };
  75
  76
  77 template<>
  78 struct get_ring<polygon_tag>
  79 {
  80     template<typename Polygon>
  81     static inline typename ring_return_type<Polygon const>::type const apply(
  82                 ring_identifier const& id,
  83                 Polygon const& polygon)
  84     {
  85         BOOST_GEOMETRY_ASSERT
  86             (
  87                 id.ring_index >= -1
  88                 && id.ring_index < int(boost::size(interior_rings(polygon)))
  89             );
  90         return id.ring_index < 0
  91             ? exterior_ring(polygon)
  92             : range::at(interior_rings(polygon), id.ring_index);
  93     }
  94 };
  95
  96
  97 template<>
  98 struct get_ring<multi_polygon_tag>
  99 {
 100     template<typename MultiPolygon>
 101     static inline typename ring_type<MultiPolygon>::type const& apply(
 102                 ring_identifier const& id,
 103                 MultiPolygon const& multi_polygon)
 104     {
 105         BOOST_GEOMETRY_ASSERT
 106             (
 107                 id.multi_index >= 0
 108                 && id.multi_index < int(boost::size(multi_polygon))
 109             );
 110         return get_ring<polygon_tag>::apply(id,
 111                     range::at(multi_polygon, id.multi_index));
 112     }
 113 };
 114
 115
 116 template <typename Geometry>
 117 inline std::size_t segment_count_on_ring(Geometry const& geometry,
 118                                          segment_identifier const& seg_id)
 119 {
 120     typedef typename geometry::tag<Geometry>::type tag;
 121     ring_identifier const rid(0, seg_id.multi_index, seg_id.ring_index);
 122     // A closed polygon, a triangle of 4 points, including starting point,
 123     // contains 3 segments. So handle as if closed and subtract one.
 124     return geometry::num_points(detail::overlay::get_ring<tag>::apply(rid, geometry), true) - 1;
 125 }
 126
 127 }} // namespace detail::overlay
 128 #endif // DOXYGEN_NO_DETAIL
 129
 130
 131 }} // namespace boost::geometry
 132
 133
 134 #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_RING_HPP