minimum counts for tokens should always be 1

[nominatim.git] / nominatim / tokenizer / token_analysis / base.py

diff --git a/nominatim/tokenizer/token_analysis/base.py b/nominatim/tokenizer/token_analysis/base.py
index b55b4f7c2f6837bc7f30fc1ac538143aa483a0f5..c7ec61c9fd683c7b105b2ccb3c750995dd435e09 100644 (file)
--- a/nominatim/tokenizer/token_analysis/base.py
+++ b/nominatim/tokenizer/token_analysis/base.py
@@ -7,39 +7,90 @@
 """
 Common data types and protocols for analysers.
 """
 """
 Common data types and protocols for analysers.
 """

-from typing import TypeVar, Mapping, List, Any
+from typing import Mapping, List, Any

 
 

-from typing_extensions import Protocol
+from nominatim.typing import Protocol
+from nominatim.data.place_name import PlaceName

 
 

+class Analyzer(Protocol):
+    """ The `create()` function of an analysis module needs to return an
+        object that implements the following functions.
+    """

 
 

-T_config = TypeVar('T_config') # pylint: disable=invalid-name
+    def get_canonical_id(self, name: PlaceName) -> str:
+        """ Return the canonical form of the given name. The canonical ID must
+            be unique (the same ID must always yield the same variants) and
+            must be a form from which the variants can be derived.

 
 

-class Analyser(Protocol):
-    """ Instance of the token analyser.
-    """
+            Arguments:
+                name: Extended place name description as prepared by
+                      the sanitizers.

 
 

-    def normalize(self, name: str) -> str:
-        """ Return the normalized form of the name. This is the standard form
-            from which possible variants for the name can be derived.
+            Returns:
+                ID string with a canonical form of the name. The string may
+                    be empty, when the analyzer cannot analyze the name at all,
+                    for example because the character set in use does not match.

         """
 
         """
 

-    def get_variants_ascii(self, norm_name: str) -> List[str]:
-        """ Compute the spelling variants for the given normalized name
-            and transliterate the result.
+    def compute_variants(self, canonical_id: str) -> List[str]:
+        """ Compute the transliterated spelling variants for the given
+            canonical ID.
+
+            Arguments:
+                canonical_id: ID string previously computed with
+                              `get_canonical_id()`.
+
+            Returns:
+                A list of possible spelling variants. All strings must have
+                    been transformed with the global normalizer and
+                    transliterator ICU rules. Otherwise they cannot be matched
+                    against the input by the query frontend.
+                    The list may be empty, when there are no useful
+                    spelling variants. This may happen when an analyzer only
+                    usually outputs additional variants to the canonical spelling
+                    and there are no such variants.

         """
 
         """
 

-class AnalysisModule(Protocol[T_config]):
-    """ Protocol for analysis modules.
+
+class AnalysisModule(Protocol):
+    """ The setup of the token analysis is split into two parts:
+        configuration and analyser factory. A token analysis module must
+        therefore implement the two functions here described.

     """
 
     """
 

-    def configure(self, rules: Mapping[str, Any], normalization_rules: str) -> T_config:
+    def configure(self, rules: Mapping[str, Any],
+                  normalizer: Any, transliterator: Any) -> Any:

         """ Prepare the configuration of the analysis module.
             This function should prepare all data that can be shared
             between instances of this analyser.
         """ Prepare the configuration of the analysis module.
             This function should prepare all data that can be shared
             between instances of this analyser.

+
+            Arguments:
+                rules: A dictionary with the additional configuration options
+                       as specified in the tokenizer configuration.
+                normalizer: an ICU Transliterator with the compiled
+                            global normalization rules.
+                transliterator: an ICU Transliterator with the compiled
+                                global transliteration rules.
+
+            Returns:
+                A data object with configuration data. This will be handed
+                    as is into the `create()` function and may be
+                    used freely by the analysis module as needed.

         """
 
         """
 

-    def create(self, normalizer: Any, transliterator: Any, config: T_config) -> Analyser:
+    def create(self, normalizer: Any, transliterator: Any, config: Any) -> Analyzer:

         """ Create a new instance of the analyser.
             A separate instance of the analyser is created for each thread
             when used in multi-threading context.
         """ Create a new instance of the analyser.
             A separate instance of the analyser is created for each thread
             when used in multi-threading context.

+
+            Arguments:
+                normalizer: an ICU Transliterator with the compiled normalization
+                            rules.
+                transliterator: an ICU Transliterator with the compiled
+                                transliteration rules.
+                config: The object that was returned by the call to configure().
+
+            Returns:
+                A new analyzer instance. This must be an object that implements
+                    the Analyzer protocol.

         """
         """