211 lines
4.9 KiB
C++
211 lines
4.9 KiB
C++
// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2015-2020, Oracle and/or its affiliates.
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// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
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// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
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// Licensed under the Boost Software License version 1.0.
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// http://www.boost.org/users/license.html
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#ifndef BOOST_GEOMETRY_ALGORITHMS_IS_EMPTY_HPP
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#define BOOST_GEOMETRY_ALGORITHMS_IS_EMPTY_HPP
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#include <boost/range/begin.hpp>
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#include <boost/range/empty.hpp>
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#include <boost/range/end.hpp>
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#include <boost/variant/apply_visitor.hpp>
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#include <boost/variant/static_visitor.hpp>
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#include <boost/variant/variant_fwd.hpp>
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#include <boost/geometry/core/exterior_ring.hpp>
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#include <boost/geometry/core/interior_rings.hpp>
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#include <boost/geometry/core/tag.hpp>
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#include <boost/geometry/core/tags.hpp>
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#include <boost/geometry/algorithms/not_implemented.hpp>
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#include <boost/geometry/algorithms/detail/check_iterator_range.hpp>
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#include <boost/geometry/geometries/concepts/check.hpp>
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namespace boost { namespace geometry
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{
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#ifndef DOXYGEN_NO_DETAIL
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namespace detail { namespace is_empty
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{
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struct always_not_empty
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{
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template <typename Geometry>
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static inline bool apply(Geometry const&)
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{
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return false;
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}
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};
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struct range_is_empty
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{
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template <typename Range>
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static inline bool apply(Range const& range)
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{
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return boost::empty(range);
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}
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};
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class polygon_is_empty
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{
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template <typename InteriorRings>
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static inline bool check_interior_rings(InteriorRings const& interior_rings)
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{
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return check_iterator_range
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<
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range_is_empty, true // allow empty range
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>::apply(boost::begin(interior_rings), boost::end(interior_rings));
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}
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public:
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template <typename Polygon>
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static inline bool apply(Polygon const& polygon)
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{
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return boost::empty(exterior_ring(polygon))
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&& check_interior_rings(interior_rings(polygon));
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}
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};
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template <typename Policy = range_is_empty>
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struct multi_is_empty
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{
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template <typename MultiGeometry>
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static inline bool apply(MultiGeometry const& multigeometry)
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{
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return check_iterator_range
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<
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Policy, true // allow empty range
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>::apply(boost::begin(multigeometry), boost::end(multigeometry));
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}
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};
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}} // namespace detail::is_empty
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#endif // DOXYGEN_NO_DETAIL
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#ifndef DOXYGEN_NO_DISPATCH
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namespace dispatch
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{
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template <typename Geometry, typename Tag = typename tag<Geometry>::type>
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struct is_empty : not_implemented<Tag>
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{};
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template <typename Geometry>
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struct is_empty<Geometry, point_tag>
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: detail::is_empty::always_not_empty
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{};
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template <typename Geometry>
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struct is_empty<Geometry, box_tag>
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: detail::is_empty::always_not_empty
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{};
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template <typename Geometry>
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struct is_empty<Geometry, segment_tag>
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: detail::is_empty::always_not_empty
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{};
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template <typename Geometry>
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struct is_empty<Geometry, linestring_tag>
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: detail::is_empty::range_is_empty
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{};
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template <typename Geometry>
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struct is_empty<Geometry, ring_tag>
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: detail::is_empty::range_is_empty
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{};
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template <typename Geometry>
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struct is_empty<Geometry, polygon_tag>
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: detail::is_empty::polygon_is_empty
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{};
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template <typename Geometry>
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struct is_empty<Geometry, multi_point_tag>
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: detail::is_empty::range_is_empty
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{};
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template <typename Geometry>
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struct is_empty<Geometry, multi_linestring_tag>
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: detail::is_empty::multi_is_empty<>
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{};
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template <typename Geometry>
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struct is_empty<Geometry, multi_polygon_tag>
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: detail::is_empty::multi_is_empty<detail::is_empty::polygon_is_empty>
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{};
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} // namespace dispatch
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#endif // DOXYGEN_NO_DISPATCH
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namespace resolve_variant
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{
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template <typename Geometry>
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struct is_empty
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{
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static inline bool apply(Geometry const& geometry)
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{
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concepts::check<Geometry const>();
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return dispatch::is_empty<Geometry>::apply(geometry);
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}
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};
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template <BOOST_VARIANT_ENUM_PARAMS(typename T)>
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struct is_empty<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> >
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{
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struct visitor : boost::static_visitor<bool>
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{
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template <typename Geometry>
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inline bool operator()(Geometry const& geometry) const
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{
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return is_empty<Geometry>::apply(geometry);
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}
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};
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static bool
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apply(boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const& geometry)
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{
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return boost::apply_visitor(visitor(), geometry);
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}
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};
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} // namespace resolve_variant
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/*!
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\brief \brief_check{is the empty set}
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\ingroup is_empty
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\tparam Geometry \tparam_geometry
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\param geometry \param_geometry
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\return \return_check{is the empty set}
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\qbk{[include reference/algorithms/is_empty.qbk]}
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*/
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template <typename Geometry>
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inline bool is_empty(Geometry const& geometry)
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{
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return resolve_variant::is_empty<Geometry>::apply(geometry);
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}
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_ALGORITHMS_IS_EMPTY_HPP
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