Merge pull request #3675 from TuringVerified/generic-preprocessors

Add generic preprocessors

src/nominatim_api/query_preprocessing/regex_replace.py

@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2025 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+This preprocessor replaces values in a given input based on pre-defined regex rules.
+
+Arguments:
+    pattern: Regex pattern to be applied on the input
+    replace: The string that it is to be replaced with
+"""
+from typing import List
+import re
+
+from .config import QueryConfig
+from .base import QueryProcessingFunc
+from ..search.query import Phrase
+
+
+class _GenericPreprocessing:
+    """Perform replacements to input phrases using custom regex patterns."""
+
+    def __init__(self, config: QueryConfig) -> None:
+        """Initialise the _GenericPreprocessing class with patterns from the ICU config file."""
+        self.config = config
+
+        match_patterns = self.config.get('replacements', 'Key not found')
+        self.compiled_patterns = [
+            (re.compile(item['pattern']), item['replace']) for item in match_patterns
+            ]
+
+    def split_phrase(self, phrase: Phrase) -> Phrase:
+        """This function performs replacements on the given text using regex patterns."""
+        for item in self.compiled_patterns:
+            phrase.text = item[0].sub(item[1], phrase.text)
+
+        return phrase
+
+    def __call__(self, phrases: List[Phrase]) -> List[Phrase]:
+        """
+        Return the final Phrase list.
+        Returns an empty list if there is nothing left after split_phrase.
+        """
+        result = [p for p in map(self.split_phrase, phrases) if p.text.strip()]
+        return result
+
+
+def create(config: QueryConfig) -> QueryProcessingFunc:
+    """ Create a function for generic preprocessing."""
+    return _GenericPreprocessing(config)