Merge pull request #1925 from joto/order-for-points

Add operators to make points sortable

Author: lonvia

src/geom.hpp

@@ -84,6 +84,23 @@ class point_t
         return !(a == b);
     }
 
+    /// Give points an (arbitrary) order.
+    [[nodiscard]] constexpr friend bool operator<(point_t a, point_t b) noexcept
+    {
+        if (a.x() == b.x()) {
+            return a.y() < b.y();
+        }
+        return a.x() < b.x();
+    }
+
+    [[nodiscard]] constexpr friend bool operator>(point_t a, point_t b) noexcept
+    {
+        if (a.x() == b.x()) {
+            return a.y() > b.y();
+        }
+        return a.x() > b.x();
+    }
+
 private:
     double m_x = 0.0;
     double m_y = 0.0;

tests/test-geom-points.cpp

@@ -61,6 +61,24 @@ TEST_CASE("create_point from OSM data", "[NoDB]")
     REQUIRE(geom.get<geom::point_t>() == geom::point_t{1.1, 2.2});
 }
 
+TEST_CASE("point order", "[NoDB]")
+{
+    geom::point_t const p{10, 10};
+    REQUIRE_FALSE(p < p);
+    REQUIRE_FALSE(p > p);
+
+    std::vector<geom::point_t> points = {
+        {10, 10}, {20, 10}, {13, 14}, {13, 10}
+    };
+
+    std::sort(points.begin(), points.end());
+
+    REQUIRE(points[0] == geom::point_t(10, 10));
+    REQUIRE(points[1] == geom::point_t(13, 10));
+    REQUIRE(points[2] == geom::point_t(13, 14));
+    REQUIRE(points[3] == geom::point_t(20, 10));
+}
+
 TEST_CASE("geom::distance", "[NoDB]")
 {
     geom::point_t const p1{10, 10};