[length] Add support for DynamicGeometry and GeometryCollection in length().

include/boost/geometry/algorithms/length.hpp

@@ -34,10 +34,13 @@
 #include <boost/geometry/algorithms/detail/dummy_geometries.hpp>
 #include <boost/geometry/algorithms/detail/multi_sum.hpp>
 // #include <boost/geometry/algorithms/detail/throw_on_empty_input.hpp>
+#include <boost/geometry/algorithms/detail/visit.hpp>
 
 #include <boost/geometry/core/cs.hpp>
 #include <boost/geometry/core/closure.hpp>
+#include <boost/geometry/core/tag.hpp>
 #include <boost/geometry/core/tags.hpp>
+#include <boost/geometry/core/visit.hpp>
 
 #include <boost/geometry/geometries/adapted/boost_variant.hpp> // For backward compatibility
 #include <boost/geometry/geometries/concepts/check.hpp>
@@ -230,9 +233,9 @@ struct length<default_strategy, false>
 } // namespace resolve_strategy
 
 
-namespace resolve_variant {
+namespace resolve_dynamic {
 
-template <typename Geometry>
+template <typename Geometry, typename Tag = typename geometry::tag<Geometry>::type>
 struct length
 {
     template <typename Strategy>
@@ -243,43 +246,40 @@ struct length
     }
 };
 
-template <BOOST_VARIANT_ENUM_PARAMS(typename T)>
+template <typename Geometry>
-struct length<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> >
+struct length<Geometry, dynamic_geometry_tag>
 {
-    typedef typename default_length_result
-        <
-            boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>
-        >::type result_type;
-
     template <typename Strategy>
-    struct visitor
+    static inline typename default_length_result<Geometry>::type
-        : static_visitor<result_type>
+        apply(Geometry const& geometry, Strategy const& strategy)
     {
-        Strategy const& m_strategy;
+        typename default_length_result<Geometry>::type result = 0;
-
+        traits::visit<Geometry>::apply([&](auto const& g)
-        visitor(Strategy const& strategy)
-            : m_strategy(strategy)
-        {}
-
-        template <typename Geometry>
-        inline typename default_length_result<Geometry>::type
-        operator()(Geometry const& geometry) const
         {
-            return length<Geometry>::apply(geometry, m_strategy);
+            result = length<util::remove_cref_t<decltype(g)>>::apply(g, strategy);
-        }
+        }, geometry);
-    };
+        return result;
-
-    template <typename Strategy>
-    static inline result_type apply(
-        variant<BOOST_VARIANT_ENUM_PARAMS(T)> const& geometry,
-        Strategy const& strategy
-    )
-    {
-        return boost::apply_visitor(visitor<Strategy>(strategy), geometry);
     }
 };
 
-} // namespace resolve_variant
+template <typename Geometry>
+struct length<Geometry, geometry_collection_tag>
+{
+    template <typename Strategy>
+    static inline typename default_length_result<Geometry>::type
+        apply(Geometry const& geometry, Strategy const& strategy)
+    {
+        typename default_length_result<Geometry>::type result = 0;
+        detail::visit_breadth_first([&](auto const& g)
+        {
+            result += length<util::remove_cref_t<decltype(g)>>::apply(g, strategy);
+            return true;
+        }, geometry);
+        return result;
+    }
+};
+
+} // namespace resolve_dynamic
 
 
 /*!
@@ -301,7 +301,7 @@ length(Geometry const& geometry)
 
     // detail::throw_on_empty_input(geometry);
 
-    return resolve_variant::length<Geometry>::apply(geometry, default_strategy());
+    return resolve_dynamic::length<Geometry>::apply(geometry, default_strategy());
 }
 
 
@@ -327,7 +327,7 @@ length(Geometry const& geometry, Strategy const& strategy)
 
     // detail::throw_on_empty_input(geometry);
 
-    return resolve_variant::length<Geometry>::apply(geometry, strategy);
+    return resolve_dynamic::length<Geometry>::apply(geometry, strategy);
 }
 
 

test/algorithms/test_length.hpp

@@ -3,8 +3,9 @@
 
 // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
 
-// Copyright (c) 2016 Oracle and/or its affiliates.
+// Copyright (c) 2016-2021 Oracle and/or its affiliates.
 // Contributed and/or modified by Vissarion Fisikopoulos, on behalf of Oracle
+// 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
@@ -16,9 +17,15 @@
 #include <geometry_test_common.hpp>
 
 #include <boost/geometry/algorithms/length.hpp>
+
+#ifndef BOOST_GEOMETRY_TEST_DEBUG
+#include <boost/geometry/geometries/adapted/boost_variant.hpp>
+#include <boost/geometry/geometries/adapted/boost_variant2.hpp>
+#include <boost/geometry/geometries/geometry_collection.hpp>
+#endif
+
 #include <boost/geometry/io/wkt/wkt.hpp>
 #include <boost/geometry/strategies/strategies.hpp>
-#include <boost/variant/variant.hpp>
 
 template <typename Geometry>
 void test_length(Geometry const& geometry, long double expected_length)
@@ -66,8 +73,14 @@ void test_geometry(std::string const& wkt, double expected_length)
     Geometry geometry;
     bg::read_wkt(wkt, geometry);
     test_length(geometry, expected_length);
-#if !defined(BOOST_GEOMETRY_TEST_DEBUG)
+
-    test_length(boost::variant<Geometry>(geometry), expected_length);
+#ifndef BOOST_GEOMETRY_TEST_DEBUG
+    using variant_t = boost::variant<Geometry>;
+    using variant2_t = boost::variant2::variant<Geometry>;
+    using gc_t = bg::model::geometry_collection<variant2_t>;
+    test_length(variant_t(geometry), expected_length);
+    test_length(variant2_t(geometry), expected_length);
+    test_length(gc_t{variant2_t(geometry), variant2_t(geometry)}, expected_length * 2);
 #endif
 }
 
@@ -77,8 +90,14 @@ void test_geometry(std::string const& wkt, double expected_length, Strategy stra
     Geometry geometry;
     bg::read_wkt(wkt, geometry);
     test_length(geometry, expected_length, strategy);
-#if !defined(BOOST_GEOMETRY_TEST_DEBUG)
+
-    test_length(boost::variant<Geometry>(geometry), expected_length, strategy);
+#ifndef BOOST_GEOMETRY_TEST_DEBUG
+    using variant_t = boost::variant<Geometry>;
+    using variant2_t = boost::variant2::variant<Geometry>;
+    using gc_t = bg::model::geometry_collection<variant2_t>;
+    test_length(variant_t(geometry), expected_length, strategy);
+    test_length(variant2_t(geometry), expected_length, strategy);
+    test_length(gc_t{variant2_t(geometry), variant2_t(geometry)}, expected_length * 2, strategy);
 #endif
 }