[views] Add geometry_collection_view.

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

@@ -0,0 +1,84 @@
+// 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_GEOMETRY_COLLECTION_VIEW_HPP
+#define BOOST_GEOMETRY_VIEWS_GEOMETRY_COLLECTION_VIEW_HPP
+
+#include <boost/core/addressof.hpp>
+
+#include <boost/geometry/core/geometry_types.hpp>
+#include <boost/geometry/core/tag.hpp>
+#include <boost/geometry/core/tags.hpp>
+#include <boost/geometry/core/visit.hpp>
+#include <boost/geometry/util/sequence.hpp>
+
+namespace boost { namespace geometry
+{
+
+namespace detail
+{
+
+
+template <typename Geometry>
+class geometry_collection_view
+{
+public:
+    using iterator = Geometry const*;
+    using const_iterator = Geometry const*;
+
+    explicit geometry_collection_view(Geometry const& geometry)
+        : m_geometry(geometry)
+    {}
+
+    const_iterator begin() const { return boost::addressof(m_geometry); }
+    const_iterator end() const { return boost::addressof(m_geometry) + 1; }
+
+private:
+    Geometry const& m_geometry;
+};
+
+} // namespace detail
+
+
+#ifndef DOXYGEN_NO_TRAITS_SPECIALIZATIONS
+namespace traits
+{
+
+template <typename Geometry>
+struct tag<geometry::detail::geometry_collection_view<Geometry>>
+{
+    using type = geometry_collection_tag;
+};
+
+
+template <typename Geometry>
+struct geometry_types<geometry::detail::geometry_collection_view<Geometry>>
+{
+    using type = util::type_sequence<Geometry>;
+};
+
+
+template <typename Geometry>
+struct iter_visit<geometry::detail::geometry_collection_view<Geometry>>
+{
+    template <typename Function, typename Iterator>
+    static void apply(Function && function, Iterator iterator)
+    {
+        function(*iterator);
+    }
+};
+
+
+} // namespace traits
+#endif // DOXYGEN_NO_TRAITS_SPECIALIZATIONS
+
+
+}} // namespace boost::geometry
+
+#endif // BOOST_GEOMETRY_VIEWS_GEOMETRY_COLLECTION_VIEW_HPP