introduce and use analyzer for postcodes

lib-sql/tokenizer/icu_tokenizer.sql

@@ -223,3 +223,26 @@ BEGIN
 END;
 $$
 LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION create_postcode_word(postcode TEXT, lookup_terms TEXT[])
+  RETURNS BOOLEAN
+  AS $$
+DECLARE
+  existing INTEGER;
+BEGIN
+  SELECT count(*) INTO existing
+    FROM word WHERE word = postcode and type = 'P';
+
+  IF existing > 0 THEN
+    RETURN TRUE;
+  END IF;
+
+  -- postcodes don't need word ids
+  INSERT INTO word (word_token, type, word)
+    SELECT lookup_term, 'P', postcode FROM unnest(lookup_terms) as lookup_term;
+
+  RETURN FALSE;
+END;
+$$
+LANGUAGE plpgsql;
+

nominatim/tokenizer/icu_tokenizer.py

@@ -11,7 +11,6 @@ libICU instead of the PostgreSQL module.
 import itertools
 import json
 import logging
-import re
 from textwrap import dedent
 
 from nominatim.db.connection import connect
@@ -473,7 +472,7 @@ class LegacyICUNameAnalyzer(AbstractAnalyzer):
     def _process_place_address(self, token_info, address):
         for item in address:
             if item.kind == 'postcode':
-                self._add_postcode(item.name)
+                token_info.set_postcode(self._add_postcode(item))
             elif item.kind == 'housenumber':
                 token_info.add_housenumber(*self._compute_housenumber_token(item))
             elif item.kind == 'street':
@@ -605,26 +604,36 @@ class LegacyICUNameAnalyzer(AbstractAnalyzer):
         return full_tokens, partial_tokens
 
 
-    def _add_postcode(self, postcode):
+    def _add_postcode(self, item):
         """ Make sure the normalized postcode is present in the word table.
         """
-        if re.search(r'[:,;]', postcode) is None:
-            postcode = self.normalize_postcode(postcode)
+        analyzer = self.token_analysis.get_analyzer('@postcode')
 
-            if postcode not in self._cache.postcodes:
-                term = self._search_normalized(postcode)
-                if not term:
-                    return
+        if analyzer is None:
+            postcode_name = item.name.strip().upper()
+            variant_base = None
+        else:
+            postcode_name = analyzer.normalize(item.name)
+            variant_base = item.get_attr("variant")
 
-                with self.conn.cursor() as cur:
-                    # no word_id needed for postcodes
-                    cur.execute("""INSERT INTO word (word_token, type, word)
-                                   (SELECT %s, 'P', pc FROM (VALUES (%s)) as v(pc)
-                                    WHERE NOT EXISTS
-                                     (SELECT * FROM word
-                                      WHERE type = 'P' and word = pc))
-                                """, (term, postcode))
-                self._cache.postcodes.add(postcode)
+        if variant_base is not None:
+            postcode = f'{postcode_name}@{variant_base}'
+        else:
+            postcode = postcode_name
+
+        if postcode not in self._cache.postcodes:
+            term = self._search_normalized(postcode_name)
+            if not term:
+                return
+
+            variants = {term}
+            if analyzer is not None and variant_base is not None:
+                variants.update(analyzer.get_variants_ascii(variant_base))
+
+            with self.conn.cursor() as cur:
+                cur.execute("SELECT create_postcode_word(%s, %s)",
+                            (postcode, list(variants)))
+            self._cache.postcodes.add(postcode)
 
 
 class _TokenInfo:
@@ -637,6 +646,7 @@ class _TokenInfo:
         self.street_tokens = set()
         self.place_tokens = set()
         self.address_tokens = {}
+        self.postcode = None
 
 
     @staticmethod
@@ -701,6 +711,11 @@ class _TokenInfo:
         if partials:
             self.address_tokens[key] = self._mk_array(partials)
 
+    def set_postcode(self, postcode):
+        """ Set the postcode to the given one.
+        """
+        self.postcode = postcode
+
 
 class _TokenCache:
     """ Cache for token information to avoid repeated database queries.

nominatim/tokenizer/sanitizers/clean_postcodes.py

@@ -98,7 +98,7 @@ class _PostcodeSanitizer:
                     obj.address.pop(pos)
             else:
                 postcode.name = formatted[0]
-                postcode.set_attr('lookup', formatted[1])
+                postcode.set_attr('variant', formatted[1])
 
 
     def scan(self, postcode, country):

nominatim/tokenizer/token_analysis/postcodes.py

@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2022 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Specialized processor for postcodes. Supports a 'lookup' variant of the
+token, which produces variants with optional spaces.
+"""
+
+from nominatim.tokenizer.token_analysis.generic_mutation import MutationVariantGenerator
+
+### Configuration section
+
+def configure(rules, normalization_rules): # pylint: disable=W0613
+    """ All behaviour is currently hard-coded.
+    """
+    return None
+
+### Analysis section
+
+def create(normalizer, transliterator, config): # 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.
+    """
+    def __init__(self, norm, trans):
+        self.norm = norm
+        self.trans = trans
+
+        self.mutator = MutationVariantGenerator(' ', (' ', ''))
+
+
+    def normalize(self, name):
+        """ Return the standard form of the postcode.
+        """
+        return name.strip().upper()
+
+
+    def get_variants_ascii(self, norm_name):
+        """ 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.
+        """
+        # 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)])]

settings/icu_tokenizer.yaml

@@ -34,7 +34,7 @@ sanitizers:
         - (\A|.*,)[^\d,]{3,}(,.*|\Z)
     - step: clean-postcodes
       convert-to-address: yes
-      default-pattern: [A-Z0-9- ]{3,12}
+      default-pattern: "[A-Z0-9- ]{3,12}"
     - step: split-name-list
     - step: strip-brace-terms
     - step: tag-analyzer-by-language
@@ -46,6 +46,8 @@ token-analysis:
     - analyzer: generic
     - id: "@housenumber"
       analyzer: housenumbers
+    - id: "@postcode"
+      analyzer: postcodes
     - id: bg
       analyzer: generic
       mode: variant-only