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Nominatim/src/nominatim_api/query_preprocessing/regex_replace.py

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Python

# 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)