double length, double perimeter, double area)

{

using pt_t = P;

using mpt_t = bg::model::multi_point<pt_t>;

//using seg_t = bg::model::segment<pt_t>;

using ls_t = bg::model::linestring<pt_t>;

using mls_t = bg::model::multi_linestring<ls_t>;

//using box_t = bg::model::box<pt_t>;

using ring_t = bg::model::ring<pt_t>;

using poly_t = bg::model::polygon<pt_t>;

using mpoly_t = bg::model::multi_polygon<poly_t>;

using var_t = boost::variant<pt_t, mpt_t/*, seg_t*/, ls_t, mls_t, /*box_t,*/ ring_t, poly_t, mpoly_t>;

//using var_t = boost::variant2::variant<pt_t, mpt_t/*, seg_t*/, ls_t, mls_t, /*box_t,*/ ring_t, poly_t, mpoly_t>;

using gc_t = bg::model::geometry_collection<var_t>;

gc_t gc{

poly_t{{{0, 0},{0, 10},{10, 10},{10, 0},{0, 0}}, {{1, 1},{5, 1},{5, 5},{1, 5},{1, 1}}},

mpoly_t{{{{4, 4},{4, 6},{6, 6},{6, 4},{4, 4}}}, {{{10, 10},{10, 12},{12, 12},{12, 10},{10, 10}}}},

ring_t{{11, 11},{11, 14},{14, 14},{14, 11},{11, 11}},

//box_t{{13, 13}, {16, 16}},

mls_t{{{0, 0},{20, 20}}, {{3, 3},{3, 6},{6, 6},{6, 3},{3, 3}}},

ls_t{{3, 3},{3, 20}},

mpt_t{{2, 2},{2, 2},{5, 5},{9, 9},{11, 11},{0, 20},{1, 20}},

pt_t{0, 20}

};

gc_t result;

bg::merge_elements(gc, result);

BOOST_CHECK(boost::get<mpt_t>(result[0]).size() == points_count);

BOOST_CHECK(boost::get<mls_t>(result[1]).size() == linestrings_count);

BOOST_CHECK(boost::get<mpoly_t>(result[2]).size() == polygons_count);

auto l = bg::length(result);

auto a = bg::area(result);

auto p = bg::perimeter(result);

decltype(l) l_expected = length;

decltype(p) p_expected = perimeter;

decltype(a) a_expected = area;

BOOST_CHECK_CLOSE(l, l_expected, 0.000001);

BOOST_CHECK_CLOSE(p, p_expected, 0.000001);

BOOST_CHECK_CLOSE(a, a_expected, 0.000001);

{

test_all<bg::model::point<double, 2, bg::cs::cartesian>>(2, 5, 2, std::sqrt(2.0) * (3 + 6) + 4 + 10, 72, 97);

// TODO: right now the elements of multi geometries are not merged,

// only different geometries stored in a GC. Hence duplicated point in the result.

test_all<bg::model::point<double, 2, bg::cs::spherical_equatorial<bg::degree>>>(4, 6, 2, 0.48141804683843953, 1.2506937915396685, 0.029392562222852522);

test_all<bg::model::point<double, 2, bg::cs::geographic<bg::degree>>>(4, 6, 2, 3058383.6297531724, 7951118.1434133006, 1187967114570.5911);

return 0;