From 4919e00e2d904b3512eaaeaaf83b14be3e84534c Mon Sep 17 00:00:00 2001
From: Bruno Lalande <bruno.lalande@gmail.com>
Date: Tue, 24 Dec 2013 22:15:15 +0000
Subject: [PATCH] Made simplify variant-aware

---
 .../boost/geometry/algorithms/simplify.hpp    | 60 ++++++++++++++++++-
 test/algorithms/test_simplify.hpp             | 57 +++++++++++-------
 2 files changed, 95 insertions(+), 22 deletions(-)

diff --git a/include/boost/geometry/algorithms/simplify.hpp b/include/boost/geometry/algorithms/simplify.hpp
index 0dc2bd0c6..ad6463f01 100644
--- a/include/boost/geometry/algorithms/simplify.hpp
+++ b/include/boost/geometry/algorithms/simplify.hpp
@@ -37,6 +37,10 @@
 #include <boost/geometry/algorithms/not_implemented.hpp>
 #include <boost/geometry/algorithms/num_interior_rings.hpp>
 
+#include <boost/variant/static_visitor.hpp>
+#include <boost/variant/apply_visitor.hpp>
+#include <boost/variant/variant_fwd.hpp>
+
 
 namespace boost { namespace geometry
 {
@@ -316,6 +320,60 @@ struct simplify_insert
 } // namespace resolve_strategy
 
 
+namespace resolve_variant {
+
+template <typename Geometry>
+struct simplify
+{
+    template <typename Distance, typename Strategy>
+    static inline void apply(Geometry const& geometry,
+                             Geometry& out,
+                             Distance const& max_distance,
+                             Strategy const& strategy)
+    {
+        resolve_strategy::simplify::apply(geometry, out, max_distance, strategy);
+    }
+};
+
+template <BOOST_VARIANT_ENUM_PARAMS(typename T)>
+struct simplify<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> >
+{
+    template <typename Distance, typename Strategy>
+    struct visitor: boost::static_visitor<void>
+    {
+        Distance const& m_max_distance;
+        Strategy const& m_strategy;
+
+        visitor(Distance const& max_distance, Strategy const& strategy)
+            : m_max_distance(max_distance)
+            , m_strategy(strategy)
+        {}
+
+        template <typename Geometry>
+        void operator()(Geometry const& geometry, Geometry& out) const
+        {
+            simplify<Geometry>::apply(geometry, out, m_max_distance, m_strategy);
+        }
+    };
+
+    template <typename Distance, typename Strategy>
+    static inline void
+    apply(boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const& geometry,
+          boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>& out,
+          Distance const& max_distance,
+          Strategy const& strategy)
+    {
+        boost::apply_visitor(
+            visitor<Distance, Strategy>(max_distance, strategy),
+            geometry,
+            out
+        );
+    }
+};
+
+} // namespace resolve_variant
+
+
 /*!
 \brief Simplify a geometry using a specified strategy
 \ingroup simplify
@@ -341,7 +399,7 @@ inline void simplify(Geometry const& geometry, Geometry& out,
 
     geometry::clear(out);
 
-    resolve_strategy::simplify::apply(geometry, out, max_distance, strategy);
+    resolve_variant::simplify<Geometry>::apply(geometry, out, max_distance, strategy);
 }
 
 
diff --git a/test/algorithms/test_simplify.hpp b/test/algorithms/test_simplify.hpp
index 0eda9b3b4..b3c64ba56 100644
--- a/test/algorithms/test_simplify.hpp
+++ b/test/algorithms/test_simplify.hpp
@@ -17,8 +17,8 @@
 #include <boost/geometry/algorithms/simplify.hpp>
 #include <boost/geometry/algorithms/distance.hpp>
 #include <boost/geometry/strategies/strategies.hpp>
-
 #include <boost/geometry/io/wkt/wkt.hpp>
+#include <boost/variant/variant.hpp>
 
 template <typename Tag, typename Geometry>
 struct test_inserter
@@ -46,24 +46,43 @@ struct test_inserter<bg::linestring_tag, Geometry>
 
 
 template <typename Geometry>
-void test_geometry(std::string const& wkt, std::string const& expected, double distance)
+void check_geometry(Geometry const& geometry,
+                    std::string const& expected,
+                    double distance)
 {
-    Geometry geometry, simplified;
-
-    // Generate polygon using only integer coordinates and obvious results
-    // Polygon is a hexagon, having one extra point (2,1) on a line which should be filtered out.
-    bg::read_wkt(wkt, geometry);
+    Geometry simplified;
     bg::simplify(geometry, simplified, distance);
 
-    {
-        std::ostringstream out;
-        out << std::setprecision(12) << bg::wkt(simplified);
+    std::ostringstream out;
+    out << std::setprecision(12) << bg::wkt(simplified);
+    BOOST_CHECK_EQUAL(out.str(), expected);
+}
 
-        BOOST_CHECK_MESSAGE(out.str() == expected,
-            "simplify: " << bg::wkt(geometry)
-            << " expected " << expected
-            << " got " << out.str());
-    }
+template <typename Geometry, typename Strategy>
+void check_geometry(Geometry const& geometry,
+                    std::string const& expected,
+                    double distance,
+                    Strategy const& strategy)
+{
+    Geometry simplified;
+    bg::simplify(geometry, simplified, distance, strategy);
+
+    std::ostringstream out;
+    out << std::setprecision(12) << bg::wkt(simplified);
+    BOOST_CHECK_EQUAL(out.str(), expected);
+}
+
+template <typename Geometry>
+void test_geometry(std::string const& wkt, std::string const& expected, double distance)
+{
+    // Generate polygon using only integer coordinates and obvious results
+    // Polygon is a hexagon, having one extra point (2,1) on a line which should be filtered out.
+    Geometry geometry;
+    bg::read_wkt(wkt, geometry);
+    boost::variant<Geometry> v(geometry);
+
+    check_geometry(geometry, expected, distance);
+    check_geometry(v, expected, distance);
 
     // Check using user-specified strategy
     typedef typename bg::point_type<Geometry>::type point_type;
@@ -76,13 +95,9 @@ void test_geometry(std::string const& wkt, std::string const& expected, double d
         > simplify_strategy_type;
 
     BOOST_CONCEPT_ASSERT( (bg::concept::SimplifyStrategy<simplify_strategy_type, point_type>) );
-    bg::simplify(geometry, simplified, distance, simplify_strategy_type());
 
-    {
-        std::ostringstream out;
-        out << std::setprecision(12) << bg::wkt(simplified);
-        BOOST_CHECK_EQUAL(out.str(), expected);
-    }
+    check_geometry(geometry, expected, distance, simplify_strategy_type());
+    check_geometry(v, expected, distance, simplify_strategy_type());
 
     // Check inserter (if applicable)
     test_inserter