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https://github.com/osm-search/Nominatim.git
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10ac54b000
The algorithm is similar to the PHP reranking and uses the terms from the display name to check against the query terms. However instead of exact matching it uses a per-word-edit-distance, so that it is less strict when it comes to mismatching accents or other one letter differences. Country names get a higher penalty because they don't receive a penalty during token matching right now. This will work badly with the legacy tokenizer. Given that it is marked for removal, it is simply not worth optimising for it.
55 lines
1.8 KiB
Python
55 lines
1.8 KiB
Python
# SPDX-License-Identifier: GPL-3.0-or-later
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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) 2023 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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Factory for creating a query analyzer for the configured tokenizer.
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"""
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from typing import List, cast, TYPE_CHECKING
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from abc import ABC, abstractmethod
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from pathlib import Path
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import importlib
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from nominatim.api.logging import log
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from nominatim.api.connection import SearchConnection
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if TYPE_CHECKING:
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from nominatim.api.search.query import Phrase, QueryStruct
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class AbstractQueryAnalyzer(ABC):
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""" Class for analysing incomming queries.
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Query analyzers are tied to the tokenizer used on import.
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"""
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@abstractmethod
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async def analyze_query(self, phrases: List['Phrase']) -> 'QueryStruct':
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""" Analyze the given phrases and return the tokenized query.
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"""
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@abstractmethod
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def normalize_text(self, text: str) -> str:
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""" Bring the given text into a normalized form. That is the
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standardized form search will work with. All information removed
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at this stage is inevitably lost.
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"""
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async def make_query_analyzer(conn: SearchConnection) -> AbstractQueryAnalyzer:
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""" Create a query analyzer for the tokenizer used by the database.
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"""
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name = await conn.get_property('tokenizer')
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src_file = Path(__file__).parent / f'{name}_tokenizer.py'
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if not src_file.is_file():
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log().comment(f"No tokenizer named '{name}' available. Database not set up properly.")
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raise RuntimeError('Tokenizer not found')
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module = importlib.import_module(f'nominatim.api.search.{name}_tokenizer')
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return cast(AbstractQueryAnalyzer, await module.create_query_analyzer(conn))
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