add output formatters for ReverseResults

These formatters are written in a way that they can be reused for
search results later.

nominatim/api/v1/constants.py

@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2023 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Constants shared by all formats.
+"""
+
+import nominatim.api as napi
+
+# pylint: disable=line-too-long
+OSM_ATTRIBUTION = 'Data © OpenStreetMap contributors, ODbL 1.0. http://www.openstreetmap.org/copyright'
+
+OSM_TYPE_NAME = {
+    'N': 'node',
+    'W': 'way',
+    'R': 'relation'
+}
+
+NODE_EXTENT = [25, 25, 25, 25,
+               7,
+               2.6, 2.6, 2.0, 1.0, 1.0,
+               0.7, 0.7, 0.7,
+               0.16, 0.16, 0.16, 0.16,
+               0.04, 0.04,
+               0.02, 0.02,
+               0.01, 0.01, 0.01, 0.01, 0.01,
+               0.015, 0.015, 0.015, 0.015,
+               0.005]
+
+
+def bbox_from_result(result: napi.ReverseResult) -> napi.Bbox:
+    """ Compute a bounding box for the result. For ways and relations
+        a given boundingbox is used. For all other object, a box is computed
+        around the centroid according to dimensions dereived from the
+        search rank.
+    """
+    if (result.osm_object and result.osm_object[0] == 'N') or result.bbox is None:
+        return napi.Bbox.from_point(result.centroid, NODE_EXTENT[result.rank_search])
+
+    return result.bbox