text: // Boost.Geometry (aka GGL, Generic Geometry Library)
  // Unit Test
  
  // Copyright (c) 2010-2015 Barend Gehrels, Amsterdam, the Netherlands.
  
  // This file was modified by Oracle on 2021.
  // Modifications copyright (c) 2021 Oracle and/or its affiliates.
  // 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
  // http://www.boost.org/LICENSE_1_0.txt)
  
  #include <iostream>
  #include <string>
  
  
  #include <geometry_test_common.hpp>
  
  #include <boost/geometry/algorithms/detail/overlay/dissolver.hpp>
  
  #include <boost/geometry/strategies/strategies.hpp>
  #include <boost/geometry/geometries/point_xy.hpp>
  #include <boost/geometry/geometries/multi_polygon.hpp>
  #include <boost/geometry/io/wkt/read.hpp>
  
  
  #include <test_common/test_point.hpp>
  
  
  #if defined(TEST_WITH_SVG)
  #  include <boost/geometry/io/svg/svg_mapper.hpp>
  #  include <boost/geometry/io/svg/write_svg_multi.hpp>
  #endif
  
  // Collection might be a multi-geometry, or std::vector<ring>
  template <typename GeometryOut, typename Collection, typename T>
  void test_dissolve_plusmin(std::string const& caseid, Collection const& input,
              T const& expected_positive_area,
              T const& expected_negative_area)
  {
      typedef typename boost::range_value<GeometryOut>::type geometry_type;
      typedef typename bg::point_type<geometry_type>::type point_type;
  
  
      GeometryOut output;
      bg::dissolver(input, output);
  
      T zero = T();
      T positive_area = T();
      T negative_area = T();
  
      for (geometry_type const& geometry : output)
      {
          T a = bg::area(geometry);
          if (a > zero)
          {
              positive_area += a;
          }
          else
          {
              negative_area += a;
          }
      }
  
      BOOST_CHECK_CLOSE(positive_area, expected_positive_area, 0.001);
      BOOST_CHECK_CLOSE(negative_area, expected_negative_area, 0.001);
  
  
  #if defined(TEST_WITH_SVG)
      {
          std::ostringstream filename;
          filename << "dissolve_plusmin_"
              << caseid << ".svg";
  
          std::ofstream svg(filename.str().c_str());
  
          bg::svg_mapper<point_type> mapper(svg, 500, 500);
  
          typedef typename boost::range_value<Collection>::type value_type;
          for (value_type const& geometry : input)
          {
              mapper.add(geometry);
          }
  
          for (value_type const& geometry : input)
          {
              mapper.map(geometry,
                  "opacity:0.6;fill:rgb(0,255,0);stroke:rgb(0,0,0);stroke-width:0.5");
          }
          for (geometry_type const& geometry : output)
          {
              mapper.map(geometry,
                  bg::area(geometry) > 0
                  ? "opacity:0.5;fill:none;stroke:rgb(255,0,0);stroke-width:5"
                  : "opacity:0.5;fill:none;stroke:rgb(0,0,255);stroke-width:5"
                  );
          }
      }
  #endif
  
  }
  
  template <typename MultiPolygon, typename T>
  void test_geometry(std::string const& caseid, std::string const& wkt,
              T const& expected_positive_area,
              T const& expected_negative_area = T())
  {
  
      MultiPolygon multi_polygon;
      bg::read_wkt(wkt, multi_polygon);
  
      // Test std::vector<Polygon> (= multi_polygon)
      test_dissolve_plusmin<MultiPolygon>(caseid, multi_polygon,
          expected_positive_area,
          expected_negative_area);
  
      // Test std::vector<ring>
      {
          typedef typename boost::range_value<MultiPolygon>::type polygon_type;
          typedef typename bg::ring_type<MultiPolygon>::type ring_type;
          std::vector<ring_type> rings;
          for (polygon_type const& polygon : multi_polygon)
          {
              rings.push_back(bg::exterior_ring(polygon));
          }
  
          test_dissolve_plusmin<MultiPolygon>(caseid + "_rings", rings,
              expected_positive_area,
              expected_negative_area);
      }
  
      // Test different combinations
  #define BOOST_GEOMETRY_TEST_PERMUTATIONS
  #ifdef BOOST_GEOMETRY_TEST_PERMUTATIONS
  
      int n = multi_polygon.size();
  
      // test them in all orders
      std::vector<int> indices;
      for (int i = 0; i < n; i++)
      {
          indices.push_back(i);
      }
      int permutation = 0;
      do
      {
          std::ostringstream out;
          out << caseid;
          MultiPolygon multi_polygon2;
          for (int i = 0; i < n; i++)
          {
              int index = indices[i];
              out << "_" << index;
              multi_polygon2.push_back(multi_polygon[index]);
          }
          test_dissolve_plusmin<MultiPolygon>(out.str(), multi_polygon2, expected_positive_area,
                  expected_negative_area);
      } while (std::next_permutation(indices.begin(), indices.end()));
  #endif
  }
  
  template <typename Point>
  void test_all()
  {
      typedef bg::model::polygon<Point> polygon;
      typedef bg::model::multi_polygon<polygon> multi_polygon;
  
      test_geometry<multi_polygon>("simplex_one",
          "MULTIPOLYGON(((0 0,1 4,4 1,0 0)))",
          7.5);
  
      test_geometry<multi_polygon>("simplex_two",
          "MULTIPOLYGON(((0 0,1 4,4 1,0 0)),((2 2,3 6,6 3,2 2)))",
          14.7);
      test_geometry<multi_polygon>("simplex_three",
          "MULTIPOLYGON(((0 0,1 4,4 1,0 0)),((2 2,3 6,6 3,2 2)),((3 4,5 6,6 2,3 4)))",
          16.7945);
      test_geometry<multi_polygon>("simplex_four",
          "MULTIPOLYGON(((0 0,1 4,4 1,0 0)),((2 2,3 6,6 3,2 2)),((3 4,5 6,6 2,3 4)),((5 5,7 7,8 4,5 5)))",
          20.7581);
  
      // disjoint
      test_geometry<multi_polygon>("simplex_disjoint",
          "MULTIPOLYGON(((0 0,1 4,4 1,0 0)),((1 6,2 10,5 7,1 6)),((3 4,5 6,6 2,3 4)),((6 5,8 7,9 4,6 5)))",
          24.0);
  
      // new hole of four
      test_geometry<multi_polygon>("new_hole",
          "MULTIPOLYGON(((0 0,1 4,4 1,0 0)),((2 2,3 6,6 3,2 2)),((3 4,5 6,6 2,3 4)),((3 1,5 4,8 4,3 1)))",
          19.5206);
  
      // intersection of positive/negative ring
      test_geometry<multi_polygon>("plus_min_one",
          "MULTIPOLYGON(((0 0,1 4,4 1,0 0)),((2 2,6 3,3 6,2 2)))",
          7.5, -7.2);
  
      // negative ring within a positive ring
      test_geometry<multi_polygon>("plus_min_one_within",
          "MULTIPOLYGON(((0 0,1 7,7 3,0 0)),((1 2,4 4,2 5,1 2)))",
          23.0, -3.5);
  
      // from buffer
      test_geometry<multi_polygon>("from_buffer_1",
          "MULTIPOLYGON(((2.4 3.03431,1.71716 3.71716,2.4 4,2.4 3.03431))"
              ",((2.4 1.96569,2.4 1,1.71716 1.28284,2.4 1.96569))"
              ",((2.93431 2.5,2.4 3.03431,2.4 1.96569,2.93431 2.5))"
              ",((3.06569 2.5,3 2.43431,2.93431 2.5,3 2.56569,3.06569 2.5))"
              ",((-0.4 5.4,4.4 5.4,4.4 3.83431,3.06569 2.5,4.4 1.16569,4.4 -0.4,-0.4 -0.4,-0.4 5.4)))"
              ,
          26.0596168239, -0.2854871761);
  
  }
  
  int test_main(int, char* [])
  {
      test_all<bg::model::d2::point_xy<double> >();
      return 0;
  }
  
  
  