add factory for query analyzer

nominatim/api/search/icu_tokenizer.py

@@ -21,10 +21,7 @@ from nominatim.typing import SaRow
 from nominatim.api.connection import SearchConnection
 from nominatim.api.logging import log
 from nominatim.api.search import query as qmod
-
-# XXX: TODO
-class AbstractQueryAnalyzer:
-    pass
+from nominatim.api.search.query_analyzer_factory import AbstractQueryAnalyzer
 
 
 DB_TO_TOKEN_TYPE = {

nominatim/api/search/query_analyzer_factory.py

@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2023 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Factory for creating a query analyzer for the configured tokenizer.
+"""
+from typing import List, cast
+from abc import ABC, abstractmethod
+from pathlib import Path
+import importlib
+
+from nominatim.api.logging import log
+from nominatim.api.connection import SearchConnection
+from nominatim.api.search.query import Phrase, QueryStruct
+
+class AbstractQueryAnalyzer(ABC):
+    """ Class for analysing incomming queries.
+
+        Query analyzers are tied to the tokenizer used on import.
+    """
+
+    @abstractmethod
+    async def analyze_query(self, phrases: List[Phrase]) -> QueryStruct:
+        """ Analyze the given phrases and return the tokenized query.
+        """
+
+
+async def make_query_analyzer(conn: SearchConnection) -> AbstractQueryAnalyzer:
+    """ Create a query analyzer for the tokenizer used by the database.
+    """
+    name = await conn.get_property('tokenizer')
+
+    src_file = Path(__file__).parent / f'{name}_tokenizer.py'
+    if not src_file.is_file():
+        log().comment(f"No tokenizer named '{name}' available. Database not set up properly.")
+        raise RuntimeError('Tokenizer not found')
+
+    module = importlib.import_module(f'nominatim.api.search.{name}_tokenizer')
+
+    return cast(AbstractQueryAnalyzer, await module.create_query_analyzer(conn))