add sanitizer for TIGER tags

Currently only takes over cleaning the tiger:county data. This was
done by the import until now.

.pylintrc

@@ -15,4 +15,4 @@ ignored-classes=NominatimArgs,closing
 #   typed Python is enabled. See also https://github.com/PyCQA/pylint/issues/5273
 disable=too-few-public-methods,duplicate-code,too-many-ancestors,bad-option-value,no-self-use,not-context-manager
 
-good-names=i,x,y,fd,db,cc
+good-names=i,x,y,m,fd,db,cc

docs/customize/Tokenizers.md

@@ -213,6 +213,15 @@ The following is a list of sanitizers that are shipped with Nominatim.
     rendering:
         heading_level: 6
 
+##### clean-tiger-tags
+
+::: nominatim.tokenizer.sanitizers.clean_tiger_tags
+    selection:
+        members: False
+    rendering:
+        heading_level: 6
+
+
 
 #### Token Analysis
 

nominatim/tokenizer/sanitizers/clean_tiger_tags.py

@@ -0,0 +1,46 @@
+# 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.
+"""
+Sanitizer that preprocesses tags from the TIGER import.
+
+It makes the following changes:
+
+* remove state reference from tiger:county
+"""
+from typing import Callable
+import re
+
+from nominatim.tokenizer.sanitizers.base import ProcessInfo
+from nominatim.tokenizer.sanitizers.config import SanitizerConfig
+
+COUNTY_MATCH = re.compile('(.*), [A-Z][A-Z]')
+
+def _clean_tiger_county(obj: ProcessInfo) -> None:
+    """ Remove the state reference from tiger:county tags.
+
+        This transforms a name like 'Hamilton, AL' into 'Hamilton'.
+        If no state reference is detected at the end, the name is left as is.
+    """
+    if not obj.address:
+        return
+
+    for item in obj.address:
+        if item.kind == 'tiger' and item.suffix == 'county':
+            m = COUNTY_MATCH.fullmatch(item.name)
+            if m:
+                item.name = m[1]
+            # Switch kind and suffix, the split left them reversed.
+            item.kind = 'county'
+            item.suffix = 'tiger'
+
+            return
+
+
+def create(_: SanitizerConfig) -> Callable[[ProcessInfo], None]:
+    """ Create a housenumber processing function.
+    """
+    return _clean_tiger_county

settings/icu_tokenizer.yaml

@@ -35,6 +35,7 @@ sanitizers:
     - step: clean-postcodes
       convert-to-address: yes
       default-pattern: "[A-Z0-9- ]{3,12}"
+    - step: clean-tiger-tags
     - step: split-name-list
     - step: strip-brace-terms
     - step: tag-analyzer-by-language

test/python/tokenizer/sanitizers/test_clean_tiger_tags.py

@@ -0,0 +1,43 @@
+# 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.
+"""
+Tests for sanitizer that clean up TIGER tags.
+"""
+import pytest
+
+from nominatim.tokenizer.place_sanitizer import PlaceSanitizer
+from nominatim.data.place_info import PlaceInfo
+
+class TestCleanTigerTags:
+
+    @pytest.fixture(autouse=True)
+    def setup_country(self, def_config):
+        self.config = def_config
+
+
+    def run_sanitizer_on(self, addr):
+        place = PlaceInfo({'address': addr})
+        _, outaddr = PlaceSanitizer([{'step': 'clean-tiger-tags'}], self.config).process_names(place)
+
+        return sorted([(p.name, p.kind, p.suffix) for p in outaddr])
+
+    @pytest.mark.parametrize('inname,outname', [('Hamilton, AL', 'Hamilton'),
+                                                ('Little, Borough, CA', 'Little, Borough')])
+    def test_well_formatted(self, inname, outname):
+        assert self.run_sanitizer_on({'tiger:county': inname})\
+            == [(outname, 'county', 'tiger')]
+
+
+    @pytest.mark.parametrize('name', ('Hamilton', 'Big, Road', ''))
+    def test_badly_formatted(self, name):
+        assert self.run_sanitizer_on({'tiger:county': name})\
+            == [(name, 'county', 'tiger')]
+
+
+    def test_unmatched(self):
+        assert self.run_sanitizer_on({'tiger:country': 'US'})\
+            == [('US', 'tiger', 'country')]