Add linestring type

Author: joto

src/geom.cpp

@@ -9,6 +9,9 @@
 
 #include "geom.hpp"
 
+#include <algorithm>
+#include <iterator>
+
 namespace geom {
 
 double distance(osmium::geom::Coordinates p1,
@@ -27,5 +30,28 @@ osmium::geom::Coordinates interpolate(osmium::geom::Coordinates p1,
                                      frac * (p1.y - p2.y) + p2.y};
 }
 
+linestring_t::linestring_t(
+    std::initializer_list<osmium::geom::Coordinates> coords)
+{
+    std::copy(coords.begin(), coords.end(), std::back_inserter(m_coordinates));
+}
+
+linestring_t::linestring_t(osmium::NodeRefList const &nodes,
+                           reprojection const &proj)
+{
+    osmium::Location last{};
+    for (auto const &node : nodes) {
+        auto const loc = node.location();
+        if (loc.valid() && loc != last) {
+            add_point(proj.reproject(loc));
+            last = loc;
+        }
+    }
+
+    if (size() <= 1) {
+        m_coordinates.clear();
+    }
+}
+
 } // namespace geom
 

src/geom.hpp

@@ -16,17 +16,108 @@
  * Low level geometry functions and types.
  */
 
+#include "reprojection.hpp"
+
 #include <osmium/geom/coordinates.hpp>
+#include <osmium/osm/node_ref_list.hpp>
+
+#include <initializer_list>
+#include <ostream>
+#include <vector>
 
 namespace geom {
 
+/// Calculate the Euclidean distance between two coordinates
 double distance(osmium::geom::Coordinates p1,
                 osmium::geom::Coordinates p2) noexcept;
 
 osmium::geom::Coordinates interpolate(osmium::geom::Coordinates p1,
                                       osmium::geom::Coordinates p2,
                                       double frac) noexcept;
 
+class linestring_t
+{
+public:
+    linestring_t() = default;
+
+    linestring_t(std::initializer_list<osmium::geom::Coordinates> coords);
+
+    /**
+     * Construct a linestring from a way node list. Nodes without location
+     * are ignored. Consecutive nodes with the same location will only end
+     * up once in the linestring.
+     *
+     * The resulting linestring will either be empty or have at least two
+     * points in it.
+     *
+     * \param nodes The input nodes.
+     * \param proj The projection used to project all coordinates.
+     */
+    linestring_t(osmium::NodeRefList const &nodes, reprojection const &proj);
+
+    using iterator = std::vector<osmium::geom::Coordinates>::iterator;
+
+    using const_iterator =
+        std::vector<osmium::geom::Coordinates>::const_iterator;
+
+    bool empty() const noexcept { return m_coordinates.empty(); }
+
+    std::size_t size() const noexcept { return m_coordinates.size(); }
+
+    void clear() noexcept { m_coordinates.clear(); }
+
+    void add_point(osmium::geom::Coordinates coordinates)
+    {
+        m_coordinates.emplace_back(std::move(coordinates));
+    }
+
+    iterator begin() noexcept { return m_coordinates.begin(); }
+
+    iterator end() noexcept { return m_coordinates.end(); }
+
+    const_iterator begin() const noexcept { return m_coordinates.cbegin(); }
+
+    const_iterator end() const noexcept { return m_coordinates.cend(); }
+
+    const_iterator cbegin() const noexcept { return m_coordinates.cbegin(); }
+
+    const_iterator cend() const noexcept { return m_coordinates.cend(); }
+
+    osmium::geom::Coordinates &operator[](std::size_t n) noexcept
+    {
+        return m_coordinates[n];
+    }
+
+    osmium::geom::Coordinates operator[](std::size_t n) const noexcept
+    {
+        return m_coordinates[n];
+    }
+
+private:
+    std::vector<osmium::geom::Coordinates> m_coordinates;
+
+}; // class linestring_t
+
+/// Output a linestring in WKT format. Used for debugging.
+template <typename TChar, typename TTraits>
+std::basic_ostream<TChar, TTraits> &
+operator<<(std::basic_ostream<TChar, TTraits> &out, const linestring_t &line)
+{
+    out << "LINESTRING(";
+
+    bool first = true;
+    for (auto const coord : line) {
+        if (first) {
+            first = false;
+        } else {
+            out << ',';
+        }
+        out << coord.x << ' ' << coord.y;
+    }
+
+    return out << ')';
+}
+
 } // namespace geom
 
 #endif // OSM2PGSQL_GEOM_HPP

tests/test-geom.cpp

@@ -40,3 +40,23 @@ TEST_CASE("geom::interpolate", "[NoDB]")
     REQUIRE(i3.y == 10);
 }
 
+TEST_CASE("geom::linestring_t", "[NoDB]")
+{
+    geom::linestring_t ls1;
+
+    REQUIRE(ls1.empty());
+    ls1.add_point(osmium::geom::Coordinates{17, 42});
+    ls1.add_point(osmium::geom::Coordinates{-3, 22});
+    REQUIRE(!ls1.empty());
+    REQUIRE(ls1.size() == 2);
+
+    auto it = ls1.cbegin();
+    REQUIRE(it != ls1.cend());
+    REQUIRE(it->x == 17);
+    ++it;
+    REQUIRE(it != ls1.cend());
+    REQUIRE(it->y == 22);
+    ++it;
+    REQUIRE(it == ls1.cend());
+}
+