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https://github.com/osm-search/Nominatim.git
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67 lines
2.5 KiB
Python
67 lines
2.5 KiB
Python
# SPDX-License-Identifier: GPL-2.0-only
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#
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# This file is part of Nominatim. (https://nominatim.org)
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#
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# Copyright (C) 2022 by the Nominatim developer community.
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# For a full list of authors see the git log.
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"""
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Specialized processor for postcodes. Supports a 'lookup' variant of the
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token, which produces variants with optional spaces.
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"""
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from typing import Mapping, Any, List
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from nominatim.tokenizer.token_analysis.generic_mutation import MutationVariantGenerator
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### Configuration section
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def configure(rules: Mapping[str, Any], normalization_rules: str) -> None: # pylint: disable=W0613
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""" All behaviour is currently hard-coded.
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"""
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return None
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### Analysis section
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def create(normalizer: Any, transliterator: Any, config: None) -> 'PostcodeTokenAnalysis': # pylint: disable=W0613
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""" Create a new token analysis instance for this module.
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"""
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return PostcodeTokenAnalysis(normalizer, transliterator)
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class PostcodeTokenAnalysis:
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""" Special normalization and variant generation for postcodes.
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This analyser must not be used with anything but postcodes as
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it follows some special rules: `normalize` doesn't necessarily
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need to return a standard form as per normalization rules. It
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needs to return the canonical form of the postcode that is also
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used for output. `get_variants_ascii` then needs to ensure that
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the generated variants once more follow the standard normalization
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and transliteration, so that postcodes are correctly recognised by
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the search algorithm.
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"""
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def __init__(self, norm: Any, trans: Any) -> None:
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self.norm = norm
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self.trans = trans
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self.mutator = MutationVariantGenerator(' ', (' ', ''))
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def normalize(self, name: str) -> str:
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""" Return the standard form of the postcode.
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"""
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return name.strip().upper()
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def get_variants_ascii(self, norm_name: str) -> List[str]:
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""" Compute the spelling variants for the given normalized postcode.
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Takes the canonical form of the postcode, normalizes it using the
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standard rules and then creates variants of the result where
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all spaces are optional.
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"""
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# Postcodes follow their own transliteration rules.
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# Make sure at this point, that the terms are normalized in a way
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# that they are searchable with the standard transliteration rules.
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return [self.trans.transliterate(term) for term in
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self.mutator.generate([self.norm.transliterate(norm_name)]) if term]
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