X-Git-Url: https://git.openstreetmap.org./nominatim.git/blobdiff_plain/bb175cc95898de420781867973b38d033c187e81..7b0e0dfd883b268b58a721e2967303fa368e563f:/nominatim/tokenizer/base.py

diff --git a/nominatim/tokenizer/base.py b/nominatim/tokenizer/base.py
index c88c39f0..061cff36 100644
--- a/nominatim/tokenizer/base.py
+++ b/nominatim/tokenizer/base.py
@@ -1,14 +1,21 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2022 by the Nominatim developer community.
+# For a full list of authors see the git log.
 """
-Abstract class defintions for tokenizers. These base classes are here
+Abstract class definitions for tokenizers. These base classes are here
 mainly for documentation purposes.
 """
 from abc import ABC, abstractmethod
-from typing import List, Tuple, Dict, Any
+from typing import List, Tuple, Dict, Any, Optional, Iterable
+from pathlib import Path
 
 from nominatim.config import Configuration
-from nominatim.indexer.place_info import PlaceInfo
-
-# pylint: disable=unnecessary-pass
+from nominatim.db.connection import Connection
+from nominatim.data.place_info import PlaceInfo
+from nominatim.typing import Protocol
 
 class AbstractAnalyzer(ABC):
     """ The analyzer provides the functions for analysing names and building
@@ -22,7 +29,7 @@ class AbstractAnalyzer(ABC):
         return self
 
 
-    def __exit__(self, exc_type, exc_value, traceback) -> None:
+    def __exit__(self, exc_type: Any, exc_value: Any, traceback: Any) -> None:
         self.close()
 
 
@@ -46,8 +53,8 @@ class AbstractAnalyzer(ABC):
 
             Returns:
                 The function returns the list of all tuples that could be
-                found for the given words. Each list entry is a tuple of
-                (original word, word token, word id).
+                    found for the given words. Each list entry is a tuple of
+                    (original word, word token, word id).
         """
 
 
@@ -74,7 +81,8 @@ class AbstractAnalyzer(ABC):
 
 
     @abstractmethod
-    def update_special_phrases(self, phrases: List[Tuple[str, str, str, str]],
+    def update_special_phrases(self,
+                               phrases: Iterable[Tuple[str, str, str, str]],
                                should_replace: bool) -> None:
         """ Update the tokenizer's special phrase tokens from the given
             list of special phrases.
@@ -89,7 +97,7 @@ class AbstractAnalyzer(ABC):
 
 
     @abstractmethod
-    def add_country_names(self, country_code: str, names: Dict[str, str]):
+    def add_country_names(self, country_code: str, names: Dict[str, str]) -> None:
         """ Add the given names to the tokenizer's list of country tokens.
 
             Arguments:
@@ -106,11 +114,11 @@ class AbstractAnalyzer(ABC):
             the search index.
 
             Arguments:
-                place: Place information retrived from the database.
+                place: Place information retrieved from the database.
 
             Returns:
                 A JSON-serialisable structure that will be handed into
-                the database via the `token_info` field.
+                    the database via the `token_info` field.
         """
 
 
@@ -134,10 +142,8 @@ class AbstractTokenizer(ABC):
 
               init_db: When set to False, then initialisation of database
                 tables should be skipped. This option is only required for
-                migration purposes and can be savely ignored by custom
+                migration purposes and can be safely ignored by custom
                 tokenizers.
-
-            TODO: can we move the init_db parameter somewhere else?
         """
 
 
@@ -180,7 +186,7 @@ class AbstractTokenizer(ABC):
 
 
     @abstractmethod
-    def check_database(self, config: Configuration) -> str:
+    def check_database(self, config: Configuration) -> Optional[str]:
         """ Check that the database is set up correctly and ready for being
             queried.
 
@@ -189,8 +195,8 @@ class AbstractTokenizer(ABC):
 
             Returns:
               If an issue was found, return an error message with the
-              description of the issue as well as hints for the user on
-              how to resolve the issue. If everything is okay, return `None`.
+                  description of the issue as well as hints for the user on
+                  how to resolve the issue. If everything is okay, return `None`.
         """
 
 
@@ -203,6 +209,13 @@ class AbstractTokenizer(ABC):
         """
 
 
+    @abstractmethod
+    def update_word_tokens(self) -> None:
+        """ Do house-keeping on the tokenizers internal data structures.
+            Remove unused word tokens, resort data etc.
+        """
+
+
     @abstractmethod
     def name_analyzer(self) -> AbstractAnalyzer:
         """ Create a new analyzer for tokenizing names and queries
@@ -217,3 +230,24 @@ class AbstractTokenizer(ABC):
             When used outside the with construct, the caller must ensure to
             call the close() function before destructing the analyzer.
         """
+
+
+    @abstractmethod
+    def most_frequent_words(self, conn: Connection, num: int) -> List[str]:
+        """ Return a list of the most frequent full words in the database.
+
+            Arguments:
+              conn: Open connection to the database which may be used to
+                    retrieve the words.
+              num: Maximum number of words to return.
+        """
+
+
+class TokenizerModule(Protocol):
+    """ Interface that must be exported by modules that implement their
+        own tokenizer.
+    """
+
+    def create(self, dsn: str, data_dir: Path) -> AbstractTokenizer:
+        """ Factory for new tokenizers.
+        """