X-Git-Url: https://git.openstreetmap.org./nominatim.git/blobdiff_plain/75c631f08093d0cc7330d313bd3bb58cb2c1924b..d2853de47cac812193083f9b144a0bc818205dd6:/nominatim/tokenizer/base.py

diff --git a/nominatim/tokenizer/base.py b/nominatim/tokenizer/base.py
index 02bc312f..f0fd9dd0 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()
 
 
@@ -30,7 +37,6 @@ class AbstractAnalyzer(ABC):
     def close(self) -> None:
         """ Free all resources used by the analyzer.
         """
-        pass
 
 
     @abstractmethod
@@ -50,7 +56,6 @@ class AbstractAnalyzer(ABC):
                 found for the given words. Each list entry is a tuple of
                 (original word, word token, word id).
         """
-        pass
 
 
     @abstractmethod
@@ -66,7 +71,6 @@ class AbstractAnalyzer(ABC):
             Returns:
                 The given postcode after normalization.
         """
-        pass
 
 
     @abstractmethod
@@ -74,11 +78,11 @@ class AbstractAnalyzer(ABC):
         """ Update the tokenizer's postcode tokens from the current content
             of the `location_postcode` table.
         """
-        pass
 
 
     @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.
@@ -90,11 +94,10 @@ class AbstractAnalyzer(ABC):
                                 When false, just add the given phrases to the
                                 ones that already exist.
         """
-        pass
 
 
     @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:
@@ -102,7 +105,6 @@ class AbstractAnalyzer(ABC):
                               refer to.
                 names: Dictionary of name type to name.
         """
-        pass
 
 
     @abstractmethod
@@ -112,7 +114,7 @@ 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
@@ -140,12 +142,11 @@ 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?
         """
-        pass
 
 
     @abstractmethod
@@ -158,7 +159,6 @@ class AbstractTokenizer(ABC):
             Arguments:
               config: Read-only object with configuration options.
         """
-        pass
 
 
     @abstractmethod
@@ -171,7 +171,6 @@ class AbstractTokenizer(ABC):
             Arguments:
               config: Read-only object with configuration options.
         """
-        pass
 
 
     @abstractmethod
@@ -186,11 +185,10 @@ class AbstractTokenizer(ABC):
             Arguments:
               config: Read-only object with configuration options.
         """
-        pass
 
 
     @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.
 
@@ -202,7 +200,22 @@ class AbstractTokenizer(ABC):
               description of the issue as well as hints for the user on
               how to resolve the issue. If everything is okay, return `None`.
         """
-        pass
+
+
+    @abstractmethod
+    def update_statistics(self) -> None:
+        """ Recompute any tokenizer statistics necessary for efficient lookup.
+            This function is meant to be called from time to time by the user
+            to improve performance. However, the tokenizer must not depend on
+            it to be called in order to work.
+        """
+
+
+    @abstractmethod
+    def update_word_tokens(self) -> None:
+        """ Do house-keeping on the tokenizers internal data structures.
+            Remove unused word tokens, resort data etc.
+        """
 
 
     @abstractmethod
@@ -219,4 +232,20 @@ class AbstractTokenizer(ABC):
             When used outside the with construct, the caller must ensure to
             call the close() function before destructing the analyzer.
         """
-        pass
+
+
+    @abstractmethod
+    def most_frequent_words(self, conn: Connection, num: int) -> List[str]:
+        """ Return a list of the `num` most frequent full words
+            in the database.
+        """
+
+
+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.
+        """