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/geometries/concepts/check.hpp>
22 #include <boost/geometry/util/range.hpp>
23 
24 
25 namespace boost { namespace geometry
26 {
27 
28 
29 #ifndef DOXYGEN_NO_DETAIL
30 namespace detail { namespace overlay
31 {
32 
33 
34 template<typename Tag>
35 struct get_ring
36 {};
37 
38 // A range of rings (multi-ring but that does not exist)
39 // gets the "void" tag and is dispatched here.
40 template<>
41 struct get_ring<void>
42 {
43     template<typename Range>
44     static inline typename boost::range_value<Range>::type const&
applyboost::geometry::detail::overlay::get_ring45                 apply(ring_identifier const& id, Range const& container)
46     {
47         return range::at(container, id.multi_index);
48     }
49 };
50 
51 
52 
53 
54 template<>
55 struct get_ring<ring_tag>
56 {
57     template<typename Ring>
applyboost::geometry::detail::overlay::get_ring58     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>
applyboost::geometry::detail::overlay::get_ring69     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>
applyboost::geometry::detail::overlay::get_ring81     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>
applyboost::geometry::detail::overlay::get_ring101     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 }} // namespace detail::overlay
117 #endif // DOXYGEN_NO_DETAIL
118 
119 
120 }} // namespace boost::geometry
121 
122 
123 #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_RING_HPP
124