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- // Boost.Geometry (aka GGL, Generic Geometry Library)
- // Copyright (c) 2017-2017 Barend Gehrels, Amsterdam, the Netherlands.
- // Use, modification and distribution is subject to the Boost Software License,
- // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_NEEDS_SELF_TURNS_HPP
- #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_NEEDS_SELF_TURNS_HPP
- #include <boost/range.hpp>
- #include <boost/geometry/core/tags.hpp>
- #include <boost/geometry/algorithms/num_interior_rings.hpp>
- namespace boost { namespace geometry
- {
- #ifndef DOXYGEN_NO_DETAIL
- namespace detail { namespace overlay
- {
- template
- <
- typename Geometry,
- typename Tag = typename tag<Geometry>::type
- >
- struct needs_self_turns
- {
- };
- template <typename Geometry>
- struct needs_self_turns<Geometry, box_tag>
- {
- static inline bool apply(Geometry const&)
- {
- return false;
- }
- };
- template <typename Geometry>
- struct needs_self_turns<Geometry, ring_tag>
- {
- static inline bool apply(Geometry const&)
- {
- return false;
- }
- };
- template <typename Geometry>
- struct needs_self_turns<Geometry, polygon_tag>
- {
- static inline bool apply(Geometry const& polygon)
- {
- return geometry::num_interior_rings(polygon) > 0;
- }
- };
- template <typename Geometry>
- struct needs_self_turns<Geometry, multi_polygon_tag>
- {
- static inline bool apply(Geometry const& multi)
- {
- typedef typename boost::range_value<Geometry>::type polygon_type;
- std::size_t const n = boost::size(multi);
- return n > 1 || (n == 1
- && needs_self_turns<polygon_type>
- ::apply(*boost::begin(multi)));
- }
- };
- }} // namespace detail::overlay
- #endif // DOXYGEN_NO_DETAIL
- }} // namespace boost::geometry
- #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_NEEDS_SELF_TURNS_HPP
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