Merge pull request #987 from awulkiew/feature/gc7

Two GC-related utilities

include/boost/geometry/algorithms/convert.hpp

@@ -284,6 +284,10 @@ struct multi_to_multi: private Policy
 namespace dispatch
 {
 
+// TODO: We could use std::is_assignable instead of std::is_same.
+//   Then we should rather check ! std::is_array<Geometry2>::value
+//   which is Destination.
+
 template
 <
     typename Geometry1, typename Geometry2,

include/boost/geometry/algorithms/detail/convert_point_to_point.hpp

@@ -32,6 +32,12 @@ namespace detail { namespace conversion
 {
 
 
+// TODO: Use assignment if possible.
+// WARNING: This utility is called in various places for a subset of dimensions.
+//   In such cases only some of the coordinates should be copied. Alternatively
+//   there should be a different utility for that called differently than
+//   convert_xxx, e.g. set_coordinates.
+
 template <typename Source, typename Destination, std::size_t Dimension, std::size_t DimensionCount>
 struct point_to_point
 {

include/boost/geometry/algorithms/detail/point_on_border.hpp

@@ -4,8 +4,8 @@
 // Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
 // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
 
-// This file was modified by Oracle on 2017-2020.
+// This file was modified by Oracle on 2017-2022.
-// Modifications copyright (c) 2017-2020 Oracle and/or its affiliates.
+// Modifications copyright (c) 2017-2022 Oracle and/or its affiliates.
 // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
 
 // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
@@ -25,17 +25,15 @@
 #include <boost/range/end.hpp>
 #include <boost/static_assert.hpp>
 
-#include <boost/geometry/core/tags.hpp>
-#include <boost/geometry/core/point_type.hpp>
-#include <boost/geometry/core/ring_type.hpp>
-
-#include <boost/geometry/geometries/concepts/check.hpp>
-
 #include <boost/geometry/algorithms/assign.hpp>
 #include <boost/geometry/algorithms/detail/convert_point_to_point.hpp>
 #include <boost/geometry/algorithms/detail/equals/point_point.hpp>
-
+#include <boost/geometry/core/tags.hpp>
+#include <boost/geometry/core/point_type.hpp>
+#include <boost/geometry/core/ring_type.hpp>
+#include <boost/geometry/geometries/concepts/check.hpp>
 #include <boost/geometry/util/condition.hpp>
+#include <boost/geometry/views/detail/indexed_point_view.hpp>
 
 
 namespace boost { namespace geometry
@@ -49,10 +47,10 @@ namespace detail { namespace point_on_border
 
 struct get_point
 {
-    template <typename Point>
+    template <typename Destination, typename Source>
-    static inline bool apply(Point& destination, Point const& source)
+    static inline bool apply(Destination& destination, Source const& source)
     {
-        destination = source;
+        detail::conversion::convert_point_to_point(source, destination);
         return true;
     }
 };
@@ -69,7 +67,7 @@ struct point_on_range
             return false;
         }
 
-        geometry::detail::conversion::convert_point_to_point(*begin, point);
+        detail::conversion::convert_point_to_point(*begin, point);
         return true;
     }
 
@@ -92,12 +90,13 @@ struct point_on_polygon
 };
 
 
-struct point_on_box
+struct point_on_segment_or_box
 {
-    template<typename Point, typename Box>
+    template<typename Point, typename SegmentOrBox>
-    static inline bool apply(Point& point, Box const& box)
+    static inline bool apply(Point& point, SegmentOrBox const& segment_or_box)
     {
-        detail::assign::assign_box_2d_corner<min_corner, min_corner>(box, point);
+        detail::indexed_point_view<SegmentOrBox const, 0> view(segment_or_box);
+        detail::conversion::convert_point_to_point(view, point);
         return true;
     }
 };
@@ -146,6 +145,11 @@ struct point_on_border<point_tag>
     : detail::point_on_border::get_point
 {};
 
+template <>
+struct point_on_border<segment_tag>
+    : detail::point_on_border::point_on_segment_or_box
+{};
+
 template <>
 struct point_on_border<linestring_tag>
     : detail::point_on_border::point_on_range
@@ -163,10 +167,15 @@ struct point_on_border<polygon_tag>
 
 template <>
 struct point_on_border<box_tag>
-    : detail::point_on_border::point_on_box
+    : detail::point_on_border::point_on_segment_or_box
 {};
 
 
+template <>
+struct point_on_border<multi_point_tag>
+    : detail::point_on_border::point_on_range
+{};
+
 template <>
 struct point_on_border<multi_polygon_tag>
     : detail::point_on_border::point_on_multi
@@ -189,6 +198,9 @@ struct point_on_border<multi_linestring_tag>
 #endif // DOXYGEN_NO_DISPATCH
 
 
+// TODO: We should probably rename this utility because it can return point
+//   which is in the interior of a geometry (for PointLike and LinearRings).
+
 /*!
 \brief Take point on a border
 \ingroup overlay

include/boost/geometry/algorithms/merge_elements.hpp

@@ -0,0 +1,403 @@
+// Boost.Geometry
+
+// Copyright (c) 2022, Oracle and/or its affiliates.
+
+// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
+
+// Licensed under the Boost Software License version 1.0.
+// http://www.boost.org/users/license.html
+
+#ifndef BOOST_GEOMETRY_ALGORITHMS_MERGE_ELEMENTS_HPP
+#define BOOST_GEOMETRY_ALGORITHMS_MERGE_ELEMENTS_HPP
+
+
+#include <vector>
+
+#include <boost/geometry/algorithms/detail/point_on_border.hpp>
+#include <boost/geometry/algorithms/detail/visit.hpp>
+#include <boost/geometry/algorithms/difference.hpp>
+#include <boost/geometry/algorithms/union.hpp>
+#include <boost/geometry/core/coordinate_system.hpp>
+#include <boost/geometry/core/coordinate_type.hpp>
+#include <boost/geometry/core/point_type.hpp>
+#include <boost/geometry/core/tag.hpp>
+#include <boost/geometry/core/tags.hpp>
+#include <boost/geometry/core/visit.hpp>
+#include <boost/geometry/geometries/point.hpp>
+#include <boost/geometry/policies/compare.hpp>
+#include <boost/geometry/util/range.hpp>
+#include <boost/geometry/strategies/relate/cartesian.hpp>
+#include <boost/geometry/strategies/relate/geographic.hpp>
+#include <boost/geometry/strategies/relate/spherical.hpp>
+#include <boost/geometry/strategies/spherical/compare.hpp>
+
+
+namespace boost { namespace geometry
+{
+
+
+#ifndef DOXYGEN_NO_DETAIL
+namespace detail { namespace merge_elements
+{
+
+
+template <typename T>
+using is_pla = util::bool_constant<util::is_pointlike<T>::value || util::is_linear<T>::value || util::is_areal<T>::value>;
+template <typename T, typename ...Ts>
+struct are_areal : util::bool_constant<util::is_areal<T>::value && are_areal<Ts...>::value> {};
+template <typename T>
+struct are_areal<T> : util::is_areal<T> {};
+template <typename T, typename ...Ts>
+struct are_linear : util::bool_constant<util::is_linear<T>::value && are_linear<Ts...>::value> {};
+template <typename T>
+struct are_linear<T> : util::is_linear<T> {};
+template <typename T, typename ...Ts>
+struct are_pointlike : util::bool_constant<util::is_pointlike<T>::value && are_pointlike<Ts...>::value> {};
+template <typename T>
+struct are_pointlike<T> : util::is_pointlike<T> {};
+template <typename ...Ts>
+using are_same_kind = util::bool_constant<are_areal<Ts...>::value || are_linear<Ts...>::value || are_pointlike<Ts...>::value>;
+
+
+template
+<
+    typename Geometry, typename It, typename PointLike, typename Linear, typename Areal,
+    std::enable_if_t<util::is_areal<Geometry>::value, int> = 0
+>
+inline void distribute_element(Geometry const& geometry, It it, PointLike& , Linear&, Areal& areal)
+{
+    typename geometry::point_type<Geometry>::type point;
+    if (geometry::point_on_border(point, geometry))
+    {
+        using point_t = typename Areal::value_type::first_type;
+        areal.emplace_back(point_t(geometry::get<0>(point), geometry::get<1>(point)), it);
+    }
+}
+
+template
+<
+    typename Geometry, typename It, typename PointLike, typename Linear, typename Areal,
+    std::enable_if_t<util::is_linear<Geometry>::value, int> = 0
+>
+inline void distribute_element(Geometry const& geometry, It it, PointLike& , Linear& linear, Areal& )
+{
+    typename geometry::point_type<Geometry>::type point;
+    if (geometry::point_on_border(point, geometry))
+    {
+        using point_t = typename Linear::value_type::first_type;
+        linear.emplace_back(point_t(geometry::get<0>(point), geometry::get<1>(point)), it);
+    }
+}
+
+template
+<
+    typename Geometry, typename It, typename PointLike, typename Linear, typename Areal,
+    std::enable_if_t<util::is_pointlike<Geometry>::value, int> = 0
+>
+inline void distribute_element(Geometry const& geometry, It it, PointLike& pointlike, Linear& , Areal& )
+{
+    typename geometry::point_type<Geometry>::type point;
+    if (geometry::point_on_border(point, geometry))
+    {
+        using point_t = typename Linear::value_type::first_type;
+        pointlike.emplace_back(point_t(geometry::get<0>(point), geometry::get<1>(point)), it);
+    }
+}
+
+template
+<
+    typename Geometry, typename It, typename PointLike, typename Linear, typename Areal,
+    std::enable_if_t<! is_pla<Geometry>::value, int> = 0
+>
+inline void distribute_element(Geometry const& , It , PointLike& , Linear&, Areal&)
+{}
+
+
+template
+<
+    typename Geometry, typename MultiGeometry,
+    std::enable_if_t<are_same_kind<Geometry, MultiGeometry>::value, int> = 0
+>
+inline void convert(Geometry const& geometry, MultiGeometry& result)
+{
+    geometry::convert(geometry, result);
+}
+
+template
+<
+    typename Geometry, typename MultiGeometry,
+    std::enable_if_t<! are_same_kind<Geometry, MultiGeometry>::value, int> = 0
+>
+inline void convert(Geometry const& , MultiGeometry& )
+{}
+
+
+template
+<
+    typename Geometry1, typename Geometry2, typename MultiGeometry, typename Strategy,
+    std::enable_if_t<are_same_kind<Geometry1, Geometry2, MultiGeometry>::value, int> = 0
+>
+inline void union_(Geometry1 const& geometry1, Geometry2 const& geometry2, MultiGeometry& result, Strategy const& strategy)
+{
+    geometry::union_(geometry1, geometry2, result, strategy);
+}
+
+template
+<
+    typename Geometry1, typename Geometry2, typename MultiGeometry, typename Strategy,
+    std::enable_if_t<! are_same_kind<Geometry1, Geometry2, MultiGeometry>::value, int> = 0
+>
+inline void union_(Geometry1 const& , Geometry2 const& , MultiGeometry& , Strategy const&)
+{}
+
+
+template <typename It>
+struct merge_data
+{
+    merge_data(It first_, It last_)
+        : first(first_), last(last_)
+    {}
+    It first, last;
+    bool merge_results = false;
+};
+
+template <typename GeometryCollection, typename RandomIt, typename MultiGeometry, typename Strategy>
+inline void merge(RandomIt const first, RandomIt const last, MultiGeometry& out, Strategy const& strategy)
+{
+    auto const size = last - first;
+    if (size <= 0)
+    {
+        return;
+    }
+
+    auto const less = [](auto const& l, auto const& r)
+    {
+        return geometry::less<void, -1, typename Strategy::cs_tag>()(l.first, r.first);
+    };
+
+    std::vector<merge_data<RandomIt>> stack_in;
+    std::vector<MultiGeometry> stack_out;
+    stack_in.reserve(size / 2 + 1);
+    stack_out.reserve(size / 2 + 1);
+
+    stack_in.emplace_back(first, last);
+
+    while (! stack_in.empty())
+    {
+        auto & b = stack_in.back();
+        if (! b.merge_results)
+        {
+            auto const s = b.last - b.first;
+            if (s > 2)
+            {
+                RandomIt const mid = b.first + s / 2;
+                std::nth_element(b.first, mid, b.last, less);
+                RandomIt const fir = b.first;
+                RandomIt const las = b.last;
+                b.merge_results = true;
+                stack_in.emplace_back(fir, mid);
+                stack_in.emplace_back(mid, las);
+            }
+            else if (s == 2)
+            {
+                MultiGeometry result;
+                traits::iter_visit<GeometryCollection>::apply([&](auto const& g1)
+                {
+                    traits::iter_visit<GeometryCollection>::apply([&](auto const& g2)
+                    {
+                        merge_elements::union_(g1, g2, result, strategy);
+                    }, (b.first + 1)->second);
+                }, b.first->second);
+                stack_out.push_back(std::move(result));
+                stack_in.pop_back();
+            }
+            else if (s == 1)
+            {
+                MultiGeometry result;
+                traits::iter_visit<GeometryCollection>::apply([&](auto const& g)
+                {
+                    merge_elements::convert(g, result);
+                }, b.first->second);
+                stack_out.push_back(std::move(result));
+                stack_in.pop_back();
+            }
+        }
+        else if (b.merge_results)
+        {
+            MultiGeometry m2 = std::move(stack_out.back());
+            stack_out.pop_back();
+            MultiGeometry m1 = std::move(stack_out.back());
+            stack_out.pop_back();
+            MultiGeometry result;
+            geometry::union_(m1, m2, result, strategy);
+            stack_out.push_back(std::move(result));
+            stack_in.pop_back();
+        }
+    }
+
+    out = std::move(stack_out.back());
+}
+
+struct merge_gc
+{
+    template <typename GeometryCollection, typename Strategy>
+    static void apply(GeometryCollection const& geometry_collection,
+                      GeometryCollection & out,
+                      Strategy const& strategy)
+    {
+        using original_point_t = typename geometry::point_type<GeometryCollection>::type;
+        using iterator_t = typename boost::range_iterator<GeometryCollection const>::type;
+        using coordinate_t = typename geometry::coordinate_type<original_point_t>::type;
+        using cs_t = typename geometry::coordinate_system<original_point_t>::type;
+        using point_t = model::point<coordinate_t, 2, cs_t>;
+
+        using multi_point_t = typename util::sequence_find_if
+            <
+                typename traits::geometry_types<std::remove_const_t<GeometryCollection>>::type,
+                util::is_multi_point
+            >::type;
+        using multi_linestring_t = typename util::sequence_find_if
+            <
+                typename traits::geometry_types<std::remove_const_t<GeometryCollection>>::type,
+                util::is_multi_linestring
+            >::type;
+        using multi_polygon_t = typename util::sequence_find_if
+            <
+                typename traits::geometry_types<std::remove_const_t<GeometryCollection>>::type,
+                util::is_multi_polygon
+            >::type;
+
+        // NOTE: Right now GC containing all of the above is required but technically
+        //       we could allow only some combinations and the algorithm below could
+        //       normalize GC accordingly.
+
+        multi_point_t multi_point, multi_point2;
+        multi_linestring_t multi_linestring, multi_linestring2;
+        multi_polygon_t multi_polygon;
+
+        std::vector<std::pair<point_t, iterator_t>> pointlike;
+        std::vector<std::pair<point_t, iterator_t>> linear;
+        std::vector<std::pair<point_t, iterator_t>> areal;
+
+        detail::visit_breadth_first_impl<true>::apply([&](auto const& g, auto it)
+        {
+            merge_elements::distribute_element(g, it, pointlike, linear, areal);
+            return true;
+        }, geometry_collection);
+
+        // TODO: make this optional?
+        // TODO: merge linear at the end? (difference can break linear rings, their parts would be joined)
+        merge<GeometryCollection>(pointlike.begin(), pointlike.end(), multi_point, strategy);
+        merge<GeometryCollection>(linear.begin(), linear.end(), multi_linestring, strategy);
+
+        merge<GeometryCollection>(areal.begin(), areal.end(), multi_polygon, strategy);
+
+        // L \ A
+        geometry::difference(multi_linestring, multi_polygon, multi_linestring2, strategy);
+
+        // (P \ A) \ L
+        geometry::difference(multi_point, multi_polygon, multi_point2, strategy);
+        range::clear(multi_point);
+        geometry::difference(multi_point2, multi_linestring2, multi_point, strategy);
+
+        if (! geometry::is_empty(multi_point))
+        {
+            range::emplace_back(out, std::move(multi_point));
+        }
+        if (! geometry::is_empty(multi_linestring2))
+        {
+            range::emplace_back(out, std::move(multi_linestring2));
+        }
+        if (! geometry::is_empty(multi_polygon))
+        {
+            range::emplace_back(out, std::move(multi_polygon));
+        }
+    }
+};
+
+
+}} // namespace detail::merge_elements
+#endif // DOXYGEN_NO_DETAIL
+
+
+#ifndef DOXYGEN_NO_DISPATCH
+namespace dispatch
+{
+
+
+template <typename Geometry, typename Tag = typename tag<Geometry>::type>
+struct merge_elements
+    : not_implemented<Geometry, Tag>
+{};
+
+template <typename GeometryCollection>
+struct merge_elements<GeometryCollection, geometry_collection_tag>
+    : geometry::detail::merge_elements::merge_gc
+{};
+
+
+} // namespace dispatch
+#endif
+
+
+namespace resolve_strategy
+{
+
+template <typename Strategy>
+struct merge_elements
+{
+    template <typename Geometry>
+    static void apply(Geometry const& geometry, Geometry & out, Strategy const& strategy)
+    {
+        dispatch::merge_elements
+            <
+                Geometry
+            >::apply(geometry, out, strategy);
+    }
+};
+
+template <>
+struct merge_elements<default_strategy>
+{
+    template <typename Geometry>
+    static void apply(Geometry const& geometry, Geometry & out, default_strategy)
+    {
+        using strategy_type = typename strategies::relate::services::default_strategy
+            <
+                Geometry, Geometry
+            >::type;
+
+        dispatch::merge_elements
+            <
+                Geometry
+            >::apply(geometry, out, strategy_type());
+    }
+};
+
+} // namespace resolve_strategy
+
+
+template <typename Geometry, typename Strategy>
+inline void merge_elements(Geometry const& geometry, Geometry & out, Strategy const& strategy)
+{
+    resolve_strategy::merge_elements
+        <
+            Strategy
+        >::apply(geometry, out, strategy);
+}
+
+
+template <typename Geometry>
+inline void merge_elements(Geometry const& geometry, Geometry & out)
+{
+    resolve_strategy::merge_elements
+        <
+            default_strategy
+        >::apply(geometry, out, default_strategy());
+}
+
+
+}} // namespace boost::geometry
+
+
+#endif // BOOST_GEOMETRY_ALGORITHMS_MERGE_ELEMENTS_HPP

include/boost/geometry/views/detail/random_access_view.hpp

@@ -0,0 +1,204 @@
+// Boost.Geometry
+
+// Copyright (c) 2022, Oracle and/or its affiliates.
+
+// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
+
+// Licensed under the Boost Software License version 1.0.
+// http://www.boost.org/users/license.html
+
+#ifndef BOOST_GEOMETRY_VIEWS_DETAIL_RANDOM_ACCESS_VIEW_HPP
+#define BOOST_GEOMETRY_VIEWS_DETAIL_RANDOM_ACCESS_VIEW_HPP
+
+#include <boost/range/begin.hpp>
+#include <boost/range/end.hpp>
+#include <boost/range/iterator.hpp>
+#include <boost/range/size.hpp>
+
+#include <boost/geometry/algorithms/detail/visit.hpp>
+#include <boost/geometry/core/geometry_types.hpp>
+#include <boost/geometry/core/tag.hpp>
+#include <boost/geometry/core/tags.hpp>
+#include <boost/geometry/util/sequence.hpp>
+#include <boost/geometry/util/type_traits.hpp>
+
+namespace boost { namespace geometry
+{
+
+#ifndef DOXYGEN_NO_DETAIL
+namespace detail
+{
+
+
+template <typename Range>
+struct is_random_access_range
+    : std::is_convertible
+        <
+            typename boost::iterator_traversal
+                <
+                    typename boost::range_iterator<Range>::type
+                >::type,
+            boost::random_access_traversal_tag
+        >
+{};
+
+template <typename Geometry>
+struct is_geometry_collection_recursive
+    : util::bool_constant
+        <
+            util::is_geometry_collection
+                <
+                    typename util::sequence_find_if
+                        <
+                            typename traits::geometry_types<std::remove_const_t<Geometry>>::type,
+                            util::is_geometry_collection
+                        >::type
+                >::value
+        >
+{};
+
+template
+<
+    typename GeometryCollection,
+    bool IsRandomAccess = is_random_access_range<GeometryCollection>::value,
+    bool IsRecursive = is_geometry_collection_recursive<GeometryCollection>::value
+>
+class random_access_view
+    : public std::vector<typename boost::range_iterator<GeometryCollection>::type>
+{
+    // NOTE: An alternative would be to implement iterator holding base iterators
+    //   to geometry collections of lower levels to process after the current level
+    //   of bfs traversal is finished.
+
+    using base_t = std::vector<typename boost::range_iterator<GeometryCollection>::type>;
+
+public:
+    random_access_view(GeometryCollection & geometry)
+    {
+        this->reserve(boost::size(geometry));
+        detail::visit_breadth_first_impl<true>::apply([&](auto&&, auto iter)
+        {
+            this->push_back(iter);
+            return true;
+        }, geometry);
+    }
+};
+
+template <typename GeometryCollection>
+class random_access_view<GeometryCollection, true, false>
+{
+public:
+    using iterator = typename boost::range_iterator<GeometryCollection>::type;
+    using const_iterator = typename boost::range_const_iterator<GeometryCollection>::type;
+
+    random_access_view(GeometryCollection & geometry)
+        : m_begin(boost::begin(geometry))
+        , m_end(boost::end(geometry))
+    {}
+
+    iterator begin() { return m_begin; }
+    iterator end() { return m_end; }
+    const_iterator begin() const { return m_begin; }
+    const_iterator end() const { return m_end; }
+
+private:
+    iterator m_begin, m_end;
+};
+
+
+template <typename GeometryCollection>
+struct random_access_view_iter_visit
+{
+    template <typename Function, typename Iterator>
+    static void apply(Function && function, Iterator iterator)
+    {
+        geometry::traits::iter_visit
+            <
+                std::remove_const_t<GeometryCollection>
+            >::apply(std::forward<Function>(function), *iterator);
+    }
+};
+
+
+template <typename ...Ts>
+struct remove_geometry_collections_pack
+{
+    using type = util::type_sequence<>;
+};
+
+template <typename T, typename ...Ts>
+struct remove_geometry_collections_pack<T, Ts...>
+{
+    using next_sequence = typename remove_geometry_collections_pack<Ts...>::type;
+    using type = std::conditional_t
+        <
+            util::is_geometry_collection<T>::value,
+            next_sequence,
+            typename util::sequence_merge<util::type_sequence<T>, next_sequence>::type
+        >;
+};
+
+template <typename Types>
+struct remove_geometry_collections;
+
+template <typename ...Ts>
+struct remove_geometry_collections<util::type_sequence<Ts...>>
+    : remove_geometry_collections_pack<Ts...>
+{};
+
+
+} // namespace detail
+#endif // DOXYGEN_NO_DETAIL
+
+
+#ifndef DOXYGEN_NO_TRAITS_SPECIALIZATIONS
+namespace traits
+{
+
+template<typename GeometryCollection, bool IsRandomAccess, bool IsRecursive>
+struct tag<geometry::detail::random_access_view<GeometryCollection, IsRandomAccess, IsRecursive>>
+{
+    using type = geometry_collection_tag;
+};
+
+
+template <typename GeometryCollection>
+struct iter_visit<geometry::detail::random_access_view<GeometryCollection, false, false>>
+    : geometry::detail::random_access_view_iter_visit<GeometryCollection>
+{};
+
+template <typename GeometryCollection>
+struct iter_visit<geometry::detail::random_access_view<GeometryCollection, true, true>>
+    : geometry::detail::random_access_view_iter_visit<GeometryCollection>
+{};
+
+template <typename GeometryCollection>
+struct iter_visit<geometry::detail::random_access_view<GeometryCollection, false, true>>
+    : geometry::detail::random_access_view_iter_visit<GeometryCollection>
+{};
+
+
+template <typename GeometryCollection, bool IsRandomAccess>
+struct geometry_types<geometry::detail::random_access_view<GeometryCollection, IsRandomAccess, false>>
+    : geometry_types<GeometryCollection>
+{};
+
+template <typename GeometryCollection, bool IsRandomAccess>
+struct geometry_types<geometry::detail::random_access_view<GeometryCollection, IsRandomAccess, true>>
+    : geometry::detail::remove_geometry_collections
+        <
+            typename traits::geometry_types
+                <
+                    std::remove_const_t<GeometryCollection>
+                >::type
+        >
+{};
+
+} // namespace traits
+#endif // DOXYGEN_NO_TRAITS_SPECIALIZATIONS
+
+
+}} // namespace boost::geometry
+
+
+#endif // BOOST_GEOMETRY_VIEWS_DETAIL_RANDOM_ACCESS_VIEW_HPP

test/algorithms/Jamfile

@@ -5,8 +5,8 @@
 # Copyright (c) 2009-2015 Mateusz Loskot, London, UK.
 # Copyright (c) 2018 Adam Wulkiewicz, Lodz, Poland.
 #
-# This file was modified by Oracle on 2014-2021.
+# This file was modified by Oracle on 2014-2022.
-# Modifications copyright (c) 2014-2021, Oracle and/or its affiliates.
+# Modifications copyright (c) 2014-2022, Oracle and/or its affiliates.
 #
 # Contributed and/or modified by Vissarion Fisikopoulos, on behalf of Oracle
 # Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
@@ -45,6 +45,7 @@ test-suite boost-geometry-algorithms
     [ run line_interpolate.cpp         : : : : algorithms_line_interpolate ]
     [ run make.cpp                     : : : : algorithms_make ]
     [ run maximum_gap.cpp              : : : : algorithms_maximum_gap ]
+    [ run merge_elements.cpp           : : : : algorithms_merge_elements ]
     [ run num_geometries.cpp           : : : : algorithms_num_geometries ]
     [ run num_geometries_multi.cpp     : : : : algorithms_num_geometries_multi ]
     [ run num_interior_rings.cpp       : : : : algorithms_num_interior_rings ]

test/algorithms/merge_elements.cpp

@@ -0,0 +1,77 @@
+// Boost.Geometry
+// Unit Test
+
+// Copyright (c) 2022, Oracle and/or its affiliates.
+
+// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
+
+// Licensed under the Boost Software License version 1.0.
+// http://www.boost.org/users/license.html
+
+
+#include <geometry_test_common.hpp>
+
+#include <boost/geometry/algorithms/area.hpp>
+#include <boost/geometry/algorithms/length.hpp>
+#include <boost/geometry/algorithms/merge_elements.hpp>
+#include <boost/geometry/algorithms/perimeter.hpp>
+#include <boost/geometry/geometries/adapted/boost_variant2.hpp>
+#include <boost/geometry/geometries/geometries.hpp>
+#include <boost/geometry/io/wkt/wkt.hpp>
+
+
+template <typename P>
+void test_all(std::size_t points_count, std::size_t linestrings_count, std::size_t polygons_count,
+              double length, double perimeter, double area)
+{
+    using pt_t = P;
+    using mpt_t = bg::model::multi_point<pt_t>;
+    using seg_t = bg::model::segment<pt_t>;
+    using ls_t = bg::model::linestring<pt_t>;
+    using mls_t = bg::model::multi_linestring<ls_t>;
+    using box_t = bg::model::box<pt_t>;
+    using ring_t = bg::model::ring<pt_t>;
+    using poly_t = bg::model::polygon<pt_t>;
+    using mpoly_t = bg::model::multi_polygon<poly_t>;
+    using var_t = boost::variant<pt_t, mpt_t/*, seg_t*/, ls_t, mls_t, /*box_t,*/ ring_t, poly_t, mpoly_t>;
+    //using var_t = boost::variant2::variant<pt_t, mpt_t/*, seg_t*/, ls_t, mls_t, /*box_t,*/ ring_t, poly_t, mpoly_t>;
+    using gc_t = bg::model::geometry_collection<var_t>;
+
+    gc_t gc{
+        poly_t{{{0, 0},{0, 10},{10, 10},{10, 0},{0, 0}}, {{1, 1},{5, 1},{5, 5},{1, 5},{1, 1}}},
+        mpoly_t{{{{4, 4},{4, 6},{6, 6},{6, 4},{4, 4}}}, {{{10, 10},{10, 12},{12, 12},{12, 10},{10, 10}}}},
+        ring_t{{11, 11},{11, 14},{14, 14},{14, 11},{11, 11}},
+        //box_t{{13, 13}, {16, 16}},
+        mls_t{{{0, 0},{20, 20}}, {{3, 3},{3, 6},{6, 6},{6, 3},{3, 3}}},
+        ls_t{{3, 3},{3, 20}},
+        mpt_t{{2, 2},{2, 2},{5, 5},{9, 9},{11, 11},{0, 20},{1, 20}},
+        pt_t{0, 20}
+    };
+
+    gc_t result;
+    bg::merge_elements(gc, result);
+
+    BOOST_CHECK(boost::get<mpt_t>(result[0]).size() == points_count);
+    BOOST_CHECK(boost::get<mls_t>(result[1]).size() == linestrings_count);
+    BOOST_CHECK(boost::get<mpoly_t>(result[2]).size() == polygons_count);
+    auto l = bg::length(result);
+    auto a = bg::area(result);
+    auto p = bg::perimeter(result);
+    decltype(l) l_expected = length;
+    decltype(p) p_expected = perimeter;
+    decltype(a) a_expected = area;
+    BOOST_CHECK_CLOSE(l, l_expected, 0.000001);
+    BOOST_CHECK_CLOSE(p, p_expected, 0.000001);
+    BOOST_CHECK_CLOSE(a, a_expected, 0.000001);    
+}
+
+int test_main(int, char* [])
+{
+    test_all<bg::model::point<double, 2, bg::cs::cartesian>>(2, 5, 2, std::sqrt(2.0) * (3 + 6) + 4 + 10, 72, 97);
+    // TODO: right now the elements of multi geometries are not merged,
+    //       only different geometries stored in a GC. Hence duplicated point in the result.
+    test_all<bg::model::point<double, 2, bg::cs::spherical_equatorial<bg::degree>>>(4, 6, 2, 0.48141804683843953, 1.2506937915396685, 0.029392562222852522);
+    test_all<bg::model::point<double, 2, bg::cs::geographic<bg::degree>>>(4, 6, 2, 3058383.6297531724, 7951118.1434133006, 1187967114570.5911);
+    
+    return 0;
+}

test/views/Jamfile

@@ -5,15 +5,20 @@
 # Copyright (c) 2009-2015 Mateusz Loskot, London, UK.
 # Copyright (c) 2015 Adam Wulkiewicz, Lodz, Poland.
 #
+# This file was modified by Oracle on 2022.
+# Modifications copyright (c) 2022 Oracle and/or its affiliates.
+# Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
+#
 # 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)
 
 test-suite boost-geometry-views
     :
-    [ run segment_view.cpp         : : : : views_segment_view ]
     [ run box_view.cpp             : : : : views_box_view ]
-    [ run reversible_view.cpp      : : : : views_reversible_view ]
     [ run closeable_view.cpp       : : : : views_closeable_view ]
+    [ run random_access_view.cpp   : : : : views_random_access_view ]
     [ run reversible_closeable.cpp : : : : views_reversible_closeable ]
+    [ run reversible_view.cpp      : : : : views_reversible_view ]    
+    [ run segment_view.cpp         : : : : views_segment_view ]
     ;

test/views/random_access_view.cpp

@@ -0,0 +1,123 @@
+// Boost.Geometry
+// Unit Test
+
+// Copyright (c) 2022 Oracle and/or its affiliates.
+// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
+
+// 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)
+
+
+#include <geometry_test_common.hpp>
+
+#include <boost/variant.hpp>
+
+#include <boost/geometry/views/detail/random_access_view.hpp>
+#include <boost/geometry/geometries/geometries.hpp>
+
+using point_t = bg::model::point<double, 2, bg::cs::cartesian>;
+using linestring_t = bg::model::linestring<point_t>;
+using polygon_t = bg::model::polygon<point_t>;
+using variant_t = boost::variant<point_t, linestring_t, polygon_t>;
+using gc_t = bg::model::geometry_collection<variant_t>;
+using nra_gc_t = bg::model::geometry_collection<variant_t, std::list>;
+
+struct rec_gc_t;
+using rec_var_t = boost::variant<point_t, linestring_t, polygon_t, rec_gc_t>;
+struct rec_gc_t : std::vector<rec_var_t>
+{
+    rec_gc_t() = default;
+    rec_gc_t(std::initializer_list<rec_var_t> l) : std::vector<rec_var_t>(l) {}
+};
+
+struct rec_nra_gc_t;
+using rec_nra_var_t = boost::variant<point_t, linestring_t, polygon_t, rec_nra_gc_t>;
+struct rec_nra_gc_t : std::list<rec_nra_var_t>
+{
+    rec_nra_gc_t() = default;
+    rec_nra_gc_t(std::initializer_list<rec_nra_var_t> l) : std::list<rec_nra_var_t>(l) {}
+};
+
+namespace boost { namespace geometry { namespace traits {
+    template<> struct tag<rec_gc_t> { typedef geometry_collection_tag type; };
+    template<> struct geometry_types<rec_gc_t> { typedef util::type_sequence<point_t, linestring_t, rec_gc_t, polygon_t> type; };
+}}}
+
+namespace boost { namespace geometry { namespace traits {
+    template<> struct tag<rec_nra_gc_t> { typedef geometry_collection_tag type; };
+    template<> struct geometry_types<rec_nra_gc_t> { typedef util::type_sequence<point_t, linestring_t, rec_nra_gc_t, polygon_t> type; };
+}}}
+
+template <typename GC>
+GC make_gc()
+{
+    return GC{
+        point_t{0, 0},
+        linestring_t{{1, 1}, {2, 2}},
+        polygon_t{{{3, 3}, {3, 4}, {4, 4}, {4, 3}, {3, 3}}},
+        polygon_t{{{5, 5}, {5, 6}, {6, 6}, {6, 5}, {5, 5}}}
+    };
+}
+
+template <typename GC>
+GC make_rec_gc()
+{
+    return GC{
+        point_t{0, 0},
+        GC {
+            // This should be put at the end because GC is processed in a BFS manner.
+            // So both GCs should be equivalent.
+            polygon_t{{{5, 5}, {5, 6}, {6, 6}, {6, 5}, {5, 5}}}
+        },
+        linestring_t{{1, 1}, {2, 2}},
+        polygon_t{{{3, 3}, {3, 4}, {4, 4}, {4, 3}, {3, 3}}},
+    };
+}
+
+template <typename GC, typename Make>
+void test_all(Make make)
+{
+    using view_t = bg::detail::random_access_view<GC>;
+
+    GC gc = make();
+    view_t rav{gc};
+
+    using non_gc_types = bg::util::type_sequence<point_t, linestring_t, polygon_t>;
+    using view_types = typename bg::traits::geometry_types<view_t>::type;
+    BOOST_STATIC_ASSERT((std::is_same<non_gc_types, view_types>::value));
+    BOOST_STATIC_ASSERT(bg::detail::is_random_access_range<view_t>::value);
+    BOOST_STATIC_ASSERT(! bg::detail::is_geometry_collection_recursive<view_t>::value);
+    
+    size_t s = boost::size(gc);
+    for (size_t i = 0 ; i < s ; ++i)
+    {
+        bg::traits::iter_visit<bg::detail::random_access_view<GC>>::apply([&](auto&& g)
+        {
+            using geom_t = bg::util::remove_cref_t<decltype(g)>;
+            if (i == 0) { BOOST_CHECK(bg::util::is_point<geom_t>::value); }
+            else if (i == 1) { BOOST_CHECK(bg::util::is_linestring<geom_t>::value); }
+            else { BOOST_CHECK(bg::util::is_polygon<geom_t>::value); }
+        }, rav.begin() + i);
+    }
+}
+
+int test_main(int, char* [])
+{
+    BOOST_STATIC_ASSERT(bg::detail::is_random_access_range<gc_t>::value);
+    BOOST_STATIC_ASSERT(! bg::detail::is_random_access_range<nra_gc_t>::value);
+    BOOST_STATIC_ASSERT(bg::detail::is_random_access_range<rec_gc_t>::value);
+    BOOST_STATIC_ASSERT(! bg::detail::is_random_access_range<rec_nra_gc_t>::value);
+
+    BOOST_STATIC_ASSERT(! bg::detail::is_geometry_collection_recursive<gc_t>::value);
+    BOOST_STATIC_ASSERT(! bg::detail::is_geometry_collection_recursive<nra_gc_t>::value);
+    BOOST_STATIC_ASSERT(bg::detail::is_geometry_collection_recursive<rec_gc_t>::value);
+    BOOST_STATIC_ASSERT(bg::detail::is_geometry_collection_recursive<rec_nra_gc_t>::value);
+
+    test_all<gc_t>(make_gc<gc_t>);
+    test_all<nra_gc_t>(make_gc<nra_gc_t>);
+    test_all<rec_gc_t>(make_gc<rec_gc_t>);
+    test_all<rec_nra_gc_t>(make_gc<rec_nra_gc_t>);
+
+    return 0;
+}