Add line_merge to functions callable from Lua

Author: joto

src/flex-lua-geom.cpp

@@ -119,6 +119,20 @@ static int geom_is_null(lua_State *lua_state)
     return 1;
 }
 
+static int geom_line_merge(lua_State *lua_state)
+{
+    auto const *const input_geometry = unpack_geometry(lua_state);
+
+    try {
+        auto *geom = create_lua_geometry_object(lua_state);
+        geom::line_merge(geom, *input_geometry);
+    } catch (...) {
+        return luaL_error(lua_state, "Unknown error in 'line_merge()'.\n");
+    }
+
+    return 1;
+}
+
 static int geom_num_geometries(lua_State *lua_state)
 {
     auto const *const input_geometry = unpack_geometry(lua_state);
@@ -215,6 +229,7 @@ void init_geometry_class(lua_State *lua_state)
     luaX_add_table_func(lua_state, "geometry_n", geom_geometry_n);
     luaX_add_table_func(lua_state, "geometry_type", geom_geometry_type);
     luaX_add_table_func(lua_state, "is_null", geom_is_null);
+    luaX_add_table_func(lua_state, "line_merge", geom_line_merge);
     luaX_add_table_func(lua_state, "num_geometries", geom_num_geometries);
     luaX_add_table_func(lua_state, "segmentize", geom_segmentize);
     luaX_add_table_func(lua_state, "simplify", geom_simplify);

tests/bdd/flex/geometry-multilinestring.feature

@@ -47,3 +47,37 @@ Feature: Creating (multi)linestring features from way and relations
             | R        | 30     | ST_LineString         | 1, 2, 3                          | NULL                             |
             | R        | 31     | ST_MultiLineString    | 1, 2, 3                          | 4, 5, 6                          |
 
+    Scenario:
+        Given the grid
+            | 1 | 2 |   |   |
+            |   |   | 3 | 4 |
+        And the OSM data
+            """
+            w20 Thighway=motorway Nn1,n2
+            w21 Thighway=motorway Nn2,n3
+            w22 Thighway=motorway Nn3,n4
+            r30 Ttype=route,route=road Mw20@,w21@
+            r31 Ttype=route,route=road Mw20@,w22@
+            """
+        And the lua style
+            """
+            local roads = osm2pgsql.define_relation_table('osm2pgsql_test_roads', {
+                { column = 'geom', type = 'geometry', projection = 4326 },
+                { column = 'merged', type = 'geometry', projection = 4326 }
+            })
+
+            function osm2pgsql.process_relation(object)
+                local g = object:as_multilinestring()
+                roads:insert({
+                    geom = g,
+                    merged = g:line_merge()
+                })
+            end
+            """
+        When running osm2pgsql flex
+
+        Then table osm2pgsql_test_roads contains exactly
+            | relation_id | ST_GeometryType(geom) | ST_GeometryType(merged) | ST_AsText(ST_GeometryN(merged, 1)) | ST_AsText(ST_GeometryN(merged, 2)) |
+            | 30          | ST_MultiLineString    | ST_MultiLineString      | 1, 2, 3                            | NULL                               |
+            | 31          | ST_MultiLineString    | ST_MultiLineString      | 1, 2                               | 3, 4                               |
+