Add perf_geostpsimplifystable test app

benchmarks/capi/CMakeLists.txt

@@ -20,6 +20,9 @@ target_link_libraries(perf_memleak_mp_prep PRIVATE geos_c)
 add_executable(perf_geospreparedcontains GEOSPreparedContainsPerfTest.cpp)
 target_link_libraries(perf_geospreparedcontains PRIVATE geos geos_c)
 
+add_executable(perf_geostpsimplifystable GEOSTopologyPreserveSimplifyStableTest.cpp)
+target_link_libraries(perf_geostpsimplifystable PRIVATE geos geos_c)
+
 add_executable(perf_intersection IntersectionPerfTest.cpp)
 target_link_libraries(perf_intersection PRIVATE geos geos_c)
 

benchmarks/capi/GEOSTopologyPreserveSimplifyStableTest.cpp

@@ -0,0 +1,97 @@
+/**********************************************************************
+ *
+ * GEOS - Geometry Engine Open Source
+ * http://geos.osgeo.org
+ *
+ * Copyright (C) 2024 Martin Davis 
+ *
+ * This is free software; you can redistribute and/or modify it under
+ * the terms of the GNU Lesser General Public Licence as published
+ * by the Free Software Foundation.
+ * See the COPYING file for more information.
+ *
+ **********************************************************************/
+
+/**
+ * Tests the stability of topology-preserving simplification
+ * (using GEOSTopologyPreserveSimplify).
+ * The expectation is that repeated calls to GEOSTopologyPreserveSimplify(geom, tol)
+ * produce identical results.
+ * 
+ * See https://github.com/libgeos/geos/issues/1107
+*/
+#include <geos_c.h>
+
+#include <fstream>
+#include <iostream>
+#include <sstream>
+#include <deque>
+
+GEOSGeometry* readGeom(std::string& fname) {
+    std::ifstream f(fname);
+    std::string line;
+    if (! std::getline(f, line)) {
+        return nullptr;
+    }
+    auto geom = GEOSGeomFromWKT(line.c_str());
+    f.close();
+    return geom;
+}
+
+    //----------  Run test  ---------------
+void run(std::string& fname, int nRuns, double tolerance)
+{
+    initGEOS(nullptr, nullptr);
+
+    GEOSGeometry* geom = readGeom(fname);  
+
+    int nErrors = 0;
+    for (int i = 0; i < nRuns; i++) {
+        GEOSGeometry* simp1 = GEOSTopologyPreserveSimplify(geom, tolerance);
+        GEOSGeometry* simp2 = GEOSTopologyPreserveSimplify(geom, tolerance);
+        bool isEqualExact = 1 == GEOSEqualsExact(simp1, simp2, 0.0);
+
+        GEOSGeometry* diff = GEOSSymDifference(simp1, simp2);
+        bool isDiffEmpty = 1 == GEOSisEmpty(diff);
+
+        //std::cout << "Run " << i << std::endl;
+        if (! isEqualExact || ! isDiffEmpty) {
+            nErrors++;
+            std::cout << "simplified results are not identical" << std::endl;
+            std::cout << diff << std::endl;
+        }
+
+        GEOSGeom_destroy(simp1);
+        GEOSGeom_destroy(simp2);
+        GEOSGeom_destroy(diff);
+    }
+    std::cout << "Number of tests with non-identical results: " << nErrors << std::endl;
+    if (nErrors > 0) {
+        std::cout << "ERRORS FOUND " << std::endl;
+    }
+
+    GEOSGeom_destroy(geom);
+}
+
+int main(int argc, char** argv) {
+    if (argc != 4) {
+        std::cout << "Reads a geometry from a WKT file" << std::endl;
+        std::cout << "and executes GEOSTopologyPreserveSimplify(geom, TOL) N times," << std::endl;
+        std::cout << "checking that the results are identical" << std::endl;
+        std::cout << std::endl;
+        std::cout << "Usage: perf_geostpsimplifystable wktfile TOL N" << std::endl;
+        return 0;
+    }
+
+    std::string fname{argv[1]};
+    std::cout << "Reading geometry from " << fname << std::endl;
+
+    double tolerance = atof(argv[2]);
+    std::cout << "Tolerance: " << tolerance << std::endl;
+
+    int nRuns = std::atoi(argv[3]);
+    std::cout << "Performing " << nRuns << " tests." << std::endl;
+
+    run(fname, nRuns, tolerance);
+}
+