Overlay with mixed dimension (#923)

For overlay operations (union/difference/intersection/symdifference) support for GeometryCollection has been missing, at least for those cases of GeometryCollection that contain a mixture of types (point/line/polygon).

This fix tests inputs to HeuristicOverlay (formerly a wide-ranging set of shims to work around issues with the old overlay code) and for those that are mixed-type collections, processes the component dimensions separately, with appropriate logic for the overlay operation being run. Fixes GH-797.

include/geos/geom/Geometry.h

@@ -364,6 +364,9 @@ class GEOS_DLL Geometry {
         return isDimensionStrict(Dimension::A);
     }
 
+    bool isMixedDimension() const;
+    bool isMixedDimension(Dimension::DimensionType* baseDim) const;
+
     bool isCollection() const {
         int t = getGeometryTypeId();
         return t == GEOS_GEOMETRYCOLLECTION ||

include/geos/geom/HeuristicOverlay.h

@@ -20,16 +20,80 @@
 #pragma once
 
 #include <geos/export.h>
+#include <geos/geom/Geometry.h>
+#include <geos/geom/Dimension.h>
+
+
 #include <memory> // for unique_ptr
+#include <vector>
 
-namespace geos {
-namespace geom { // geos::geom
 
+namespace geos {
+namespace geom {
 class Geometry;
+class GeometryFactory;
+}
+}
+
+
+namespace geos {
+namespace geom { // geos::geom
 
 std::unique_ptr<Geometry> GEOS_DLL
 HeuristicOverlay(const Geometry* g0, const Geometry* g1, int opCode);
 
+class StructuredCollection {
+
+public:
+
+    StructuredCollection(const Geometry* g)
+        : factory(g->getFactory())
+        , pt_union(nullptr)
+        , line_union(nullptr)
+        , poly_union(nullptr)
+    {
+        readCollection(g);
+        unionByDimension();
+    };
+
+    StructuredCollection()
+        : factory(nullptr)
+        , pt_union(nullptr)
+        , line_union(nullptr)
+        , poly_union(nullptr)
+    {};
+
+    void readCollection(const Geometry* g);
+    const Geometry* getPolyUnion()  const { return poly_union.get(); }
+    const Geometry* getLineUnion()  const { return line_union.get(); }
+    const Geometry* getPointUnion() const { return pt_union.get(); }
+
+    std::unique_ptr<Geometry> doUnion(const StructuredCollection& a) const;
+    std::unique_ptr<Geometry> doIntersection(const StructuredCollection& a) const;
+    std::unique_ptr<Geometry> doSymDifference(const StructuredCollection& a) const;
+    std::unique_ptr<Geometry> doDifference(const StructuredCollection& a) const;
+    std::unique_ptr<Geometry> doUnaryUnion() const;
+
+    static void toVector(const Geometry* g, std::vector<const Geometry*>& v);
+    void unionByDimension(void);
+
+
+private:
+
+    const GeometryFactory* factory;
+    std::vector<const Geometry*> pts;
+    std::vector<const Geometry*> lines;
+    std::vector<const Geometry*> polys;
+    std::unique_ptr<Geometry> pt_union;
+    std::unique_ptr<Geometry> line_union;
+    std::unique_ptr<Geometry> poly_union;
+
+};
+
+
+
+
+
 } // namespace geos::geom
 } // namespace geos
 

src/geom/Geometry.cpp

@@ -160,6 +160,34 @@ Geometry::getCentroid() const
     return std::unique_ptr<Point>(getFactory()->createPoint(centPt));
 }
 
+/* public */
+bool
+Geometry::isMixedDimension() const
+{
+    Dimension::DimensionType baseDim = Dimension::DONTCARE;
+    return isMixedDimension(&baseDim);
+}
+
+/* public */
+bool
+Geometry::isMixedDimension(Dimension::DimensionType* baseDim) const
+{
+    if (isCollection()) {
+        for (std::size_t i = 0; i < getNumGeometries(); i++) {
+            if (getGeometryN(i)->isMixedDimension(baseDim))
+                return true;
+        }
+        return false;
+    }
+    else {
+        if (*baseDim == Dimension::DONTCARE) {
+            *baseDim = getDimension();
+            return false;
+        }
+        return *baseDim != getDimension();
+    }
+}
+
 /*public*/
 bool
 Geometry::getCentroid(CoordinateXY& ret) const