New node_locations_t class for storing node locations in memory

This is a very memory-efficient storage which will be used for the new
ram middle.

tests/test-node-locations.cpp

@@ -0,0 +1,82 @@
+/**
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This file is part of osm2pgsql (https://osm2pgsql.org/).
+ *
+ * Copyright (C) 2006-2021 by the osm2pgsql developer community.
+ * For a full list of authors see the git log.
+ */
+
+#include <catch.hpp>
+
+#include "node-locations.hpp"
+
+TEST_CASE("node locations basics", "[NoDB]")
+{
+    node_locations_t nl;
+    REQUIRE(nl.size() == 0);
+
+    nl.set(3, {1.2, 3.4});
+    nl.set(5, {5.6, 7.8});
+
+    REQUIRE(nl.size() == 2);
+
+    nl.freeze();
+    REQUIRE(nl.size() == 2);
+
+    REQUIRE(nl.get(1) == osmium::Location{});
+    REQUIRE(nl.get(4) == osmium::Location{});
+    REQUIRE(nl.get(6) == osmium::Location{});
+    REQUIRE(nl.get(100) == osmium::Location{});
+
+    REQUIRE(nl.get(3) == osmium::Location{1.2, 3.4});
+    REQUIRE(nl.get(5) == osmium::Location{5.6, 7.8});
+
+    nl.clear();
+    REQUIRE(nl.size() == 0);
+}
+
+TEST_CASE("node locations in more than one block", "[NoDB]")
+{
+    node_locations_t nl;
+
+    std::size_t max_id = 0;
+
+    SECTION("max_id 0") {
+        max_id = 0;
+    }
+
+    SECTION("max_id 31") {
+        max_id = 31;
+    }
+
+    SECTION("max_id 32") {
+        max_id = 32;
+    }
+
+    SECTION("max_id 33") {
+        max_id = 33;
+    }
+
+    SECTION("max_id 64") {
+        max_id = 64;
+    }
+
+    SECTION("max_id 80") {
+        max_id = 80;
+    }
+
+    for (std::size_t id = 1; id <= max_id; ++id) {
+        nl.set(id, {id + 0.1, id + 0.2});
+    }
+
+    nl.freeze();
+    REQUIRE(nl.size() == max_id);
+
+    for (std::size_t id = 1; id <= max_id; ++id) {
+        auto const location = nl.get(id);
+        REQUIRE(location.lon() == id + 0.1);
+        REQUIRE(location.lat() == id + 0.2);
+    }
+}
+