[addresses] Generalizing the functions used for address configs so they can be reused for per-country OSM configs, etc.

scripts/geodata/configs/utils.py

@@ -0,0 +1,31 @@
+import six
+from collections import Mapping
+
+
+def recursive_merge(a, b):
+    for k, v in six.iteritems(b):
+        if isinstance(v, Mapping):
+            existing = a.get(k, v)
+            merged = recursive_merge(existing, v)
+            a[k] = merged
+        else:
+            a[k] = b[k]
+    return a
+
+
+class DoesNotExist:
+    pass
+
+
+def nested_get(obj, keys):
+    if len(keys) == 0:
+        return obj
+    try:
+        for key in keys[:-1]:
+            obj = obj.get(key, {})
+            if not hasattr(obj, 'items'):
+                return DoesNotExist
+        key = keys[-1]
+        return obj.get(key, DoesNotExist)
+    except AttributeError:
+        return DoesNotExist