move flatten_config_list into config module

For general usage by other modules.

nominatim/config.py

@@ -12,6 +12,27 @@ from nominatim.errors import UsageError
 
 LOG = logging.getLogger()
 
+
+def flatten_config_list(content, section=''):
+    """ Flatten YAML configuration lists that contain include sections
+        which are lists themselves.
+    """
+    if not content:
+        return []
+
+    if not isinstance(content, list):
+        raise UsageError(f"List expected in section '{section}'.")
+
+    output = []
+    for ele in content:
+        if isinstance(ele, list):
+            output.extend(flatten_config_list(ele, section))
+        else:
+            output.append(ele)
+
+    return output
+
+
 class Configuration:
     """ Load and manage the project configuration.
 

nominatim/tokenizer/icu_rule_loader.py

@@ -9,6 +9,7 @@ import re
 
 from icu import Transliterator
 
+from nominatim.config import flatten_config_list
 from nominatim.db.properties import set_property, get_property
 from nominatim.errors import UsageError
 from nominatim.tokenizer.icu_name_processor import ICUNameProcessor
@@ -22,23 +23,6 @@ DBCFG_IMPORT_TRANS_RULES = "tokenizer_import_transliteration"
 DBCFG_IMPORT_ANALYSIS_RULES = "tokenizer_import_analysis_rules"
 
 
-def _flatten_config_list(content):
-    if not content:
-        return []
-
-    if not isinstance(content, list):
-        raise UsageError("List expected in ICU configuration.")
-
-    output = []
-    for ele in content:
-        if isinstance(ele, list):
-            output.extend(_flatten_config_list(ele))
-        else:
-            output.append(ele)
-
-    return output
-
-
 class VariantRule:
     """ Saves a single variant expansion.
 
@@ -158,7 +142,7 @@ class ICURuleLoader:
         if content is None:
             return ''
 
-        return ';'.join(_flatten_config_list(content)) + ';'
+        return ';'.join(flatten_config_list(content, section)) + ';'
 
 
     def _parse_variant_list(self):
@@ -169,7 +153,7 @@ class ICURuleLoader:
         if not rules:
             return
 
-        rules = _flatten_config_list(rules)
+        rules = flatten_config_list(rules, 'variants')
 
         vmaker = _VariantMaker(self.normalization_rules)