X-Git-Url: https://git.openstreetmap.org./nominatim.git/blobdiff_plain/ca7b46511d41d67e229f758e638367c241815c11..d35e3c25b66d25e4a3dd073c7ba17b0c204ec8e8:/nominatim/tokenizer/token_analysis/postcodes.py

diff --git a/nominatim/tokenizer/token_analysis/postcodes.py b/nominatim/tokenizer/token_analysis/postcodes.py
index e105b132..15b20bf9 100644
--- a/nominatim/tokenizer/token_analysis/postcodes.py
+++ b/nominatim/tokenizer/token_analysis/postcodes.py
@@ -8,47 +8,59 @@
 Specialized processor for postcodes. Supports a 'lookup' variant of the
 token, which produces variants with optional spaces.
 """
+from typing import Mapping, Any, List
 
 from nominatim.tokenizer.token_analysis.generic_mutation import MutationVariantGenerator
 
 ### Configuration section
 
-def configure(rules, normalization_rules): # pylint: disable=W0613
+def configure(rules: Mapping[str, Any], normalization_rules: str) -> None: # pylint: disable=W0613
     """ All behaviour is currently hard-coded.
     """
     return None
 
 ### Analysis section
 
-def create(normalizer, transliterator, config): # pylint: disable=W0613
+def create(normalizer: Any, transliterator: Any, config: None) -> 'PostcodeTokenAnalysis': # pylint: disable=W0613
     """ Create a new token analysis instance for this module.
     """
     return PostcodeTokenAnalysis(normalizer, transliterator)
 
+
 class PostcodeTokenAnalysis:
-    """ Detects common housenumber patterns and normalizes them.
+    """ Special normalization and variant generation for postcodes.
+
+        This analyser must not be used with anything but postcodes as
+        it follows some special rules: `normalize` doesn't necessarily
+        need to return a standard form as per normalization rules. It
+        needs to return the canonical form of the postcode that is also
+        used for output. `get_variants_ascii` then needs to ensure that
+        the generated variants once more follow the standard normalization
+        and transliteration, so that postcodes are correctly recognised by
+        the search algorithm.
     """
-    def __init__(self, norm, trans):
+    def __init__(self, norm: Any, trans: Any) -> None:
         self.norm = norm
         self.trans = trans
 
         self.mutator = MutationVariantGenerator(' ', (' ', ''))
 
 
-    def normalize(self, name):
+    def normalize(self, name: str) -> str:
         """ Return the standard form of the postcode.
         """
         return name.strip().upper()
 
 
-    def get_variants_ascii(self, norm_name):
+    def get_variants_ascii(self, norm_name: str) -> List[str]:
         """ Compute the spelling variants for the given normalized postcode.
 
-            The official form creates one variant. If a 'lookup version' is
-            given, then it will create variants with optional spaces.
+            Takes the canonical form of the postcode, normalizes it using the
+            standard rules and then creates variants of the result where
+            all spaces are optional.
         """
         # Postcodes follow their own transliteration rules.
         # Make sure at this point, that the terms are normalized in a way
         # that they are searchable with the standard transliteration rules.
         return [self.trans.transliterate(term) for term in
-                self.mutator.generate([self.norm.transliterate(norm_name)])]
+                self.mutator.generate([self.norm.transliterate(norm_name)]) if term]