Add GEOSGeom_homogenize

capi/geos_c.cpp

@@ -1510,6 +1510,12 @@ extern "C" {
         return GEOSGeom_createCurvePolygon_r(handle, shell, holes, nholes);
     }
 
+    Geometry*
+    GEOSGeom_homogenize(Geometry* g)
+    {
+        return GEOSGeom_homogenize_r(handle, g);
+    }
+
     Geometry*
     GEOSGeom_clone(const Geometry* g)
     {

capi/geos_c.h.in

@@ -944,6 +944,11 @@ extern GEOSGeometry GEOS_DLL *GEOSGeom_createRectangle_r(
     double xmin, double ymin,
     double xmax, double ymax);
 
+/** \see GEOSGeom_homogenize */
+extern GEOSGeometry GEOS_DLL * GEOSGeom_homogenize_r(
+    GEOSContextHandle_t handle,
+    GEOSGeometry * g);
+
 /** \see GEOSGeom_clone */
 extern GEOSGeometry GEOS_DLL *GEOSGeom_clone_r(
     GEOSContextHandle_t handle,
@@ -3107,6 +3112,22 @@ extern GEOSGeometry GEOS_DLL *GEOSGeom_createRectangle(
     double xmin, double ymin,
     double xmax, double ymax);
 
+/**
+* Returns the most specific representation of a geometry.
+*
+* If the input is a multi-element GeometryCollection whose elements all have
+* the same type, then the input will be destroyed and a new collection
+* of an appropriate type returned (MultiLineString, MultiPolygon, etc.) If the
+* input is a single-element GeometryCollection, then the input will be
+* destroyed and the single element returned.  If the elements are not
+* homogeneous, or if the input is not a collection, it will be returned
+* unmodified. Nested collections are collapsed during processing.
+*
+* \since 3.15
+*/
+extern GEOSGeometry GEOS_DLL *GEOSGeom_homogenize(
+    GEOSGeometry* g);
+
 /**
 * Create a new copy of the input geometry.
 * \param g The geometry to copy

capi/geos_ts_c.cpp

@@ -3860,6 +3860,18 @@ extern "C" {
         });
     }
 
+    Geometry*
+    GEOSGeom_homogenize_r(GEOSContextHandle_t extHandle, Geometry* g)
+    {
+        return execute(extHandle, [&]() -> Geometry* {
+            const int srid = g->getSRID();
+
+            auto g3 = geos::operation::cluster::GeometryFlattener::flatten(std::unique_ptr<Geometry>(g));
+            g3->setSRID(srid);
+            return g3.release();
+        });
+    }
+
     Geometry*
     GEOSGeom_clone_r(GEOSContextHandle_t extHandle, const Geometry* g)
     {

include/geos/geom/util/GeometryExtracter.h

@@ -67,7 +67,7 @@ class GEOS_DLL GeometryExtracter {
          *
          * @param comps the container to extract into (will push_back to it)
          */
-        Extracter(TargetContainer& comps) : comps_(comps) {}
+        explicit Extracter(TargetContainer& comps) : comps_(comps) {}
 
         TargetContainer& comps_;
 

tests/unit/capi/GEOSGeom_homogenizeTest.cpp

@@ -0,0 +1,96 @@
+#include <tut/tut.hpp>
+// geos
+#include <geos_c.h>
+
+#include "capi_test_utils.h"
+
+namespace tut {
+struct test_capigeosgeom_homogenize : public capitest::utility {
+
+    void testHomogenize(const std::string& wkt_in, const std::string& wkt_expected) {
+        GEOSGeometry* input = fromWKT(wkt_in.c_str());
+        result_ = GEOSGeom_homogenize(input);
+        expected_ = fromWKT(wkt_expected.c_str());
+
+        ensure_geometry_equals(result_, expected_);
+    }
+
+    void testHomogenizeUnchanged(const std::string& wkt) {
+        testHomogenize(wkt, wkt);
+    }
+};
+
+typedef test_group<test_capigeosgeom_homogenize> group;
+typedef group::object object;
+
+group test_capigeosgeom_homogenize_group("capi::GEOSGeom_homogenize");
+
+template<>
+template<>
+void object::test<1>()
+{
+    set_test_name("non-collection type");
+
+    testHomogenizeUnchanged("LINESTRING (0 0, 1 1)");
+}
+
+template<>
+template<>
+void object::test<2>()
+{
+    set_test_name("non-homogeneous collection");
+
+    testHomogenizeUnchanged("GEOMETRYCOLLECTION (LINESTRING (0 0, 1 1), POINT (2 2))");
+}
+
+template<>
+template<>
+void object::test<3>()
+{
+    set_test_name("single-element collection");
+
+    testHomogenize("GEOMETRYCOLLECTION (POINT (0 2))", "POINT (0 2)");
+    testHomogenize("MULTIPOINT ((8 2))", "POINT (8 2)");
+}
+
+template<>
+template<>
+void object::test<4>()
+{
+    set_test_name("homogeneous collection");
+
+    testHomogenize("GEOMETRYCOLLECTION (LINESTRING (0 0, 1 1), LINESTRING (4 3, 2 7))",
+              "MULTILINESTRING ((0 0, 1 1), (4 3, 2 7))" );
+}
+
+template<>
+template<>
+void object::test<5>()
+{
+    set_test_name("empty collection");
+
+    testHomogenizeUnchanged("GEOMETRYCOLLECTION EMPTY");
+}
+
+template<>
+template<>
+void object::test<6>()
+{
+    set_test_name("nested homogeneous collection");
+
+    testHomogenize("GEOMETRYCOLLECTION (LINESTRING (0 0, 1 1), GEOMETRYCOLLECTION(LINESTRING EMPTY, MULTILINESTRING ((1 1, 2 2), (2 2, 3 3))))",
+        "MULTILINESTRING ((0 0, 1 1), (1 1, 2 2), (2 2, 3 3), EMPTY)");
+}
+
+template<>
+template<>
+void object::test<7>()
+{
+    set_test_name("nested non-homogeneous collection");
+
+    testHomogenize("GEOMETRYCOLLECTION (LINESTRING (0 0, 1 1), GEOMETRYCOLLECTION(COMPOUNDCURVE ((1 1, 2 2))))",
+        "MULTICURVE (LINESTRING (0 0, 1 1), COMPOUNDCURVE ((1 1, 2 2)))");
+}
+
+} // namespace tut
+