Introduction of SPCsvLoader to load special phrases from a csv file

nominatim/tools/__init__.py

@@ -2,7 +2,3 @@
 Module with functions for importing, updating Nominatim databases
 as well as general maintenance helpers.
 """
-
-from nominatim.tools.special_phrases.sp_importer import SPImporter
-from nominatim.tools.special_phrases.sp_wiki_loader import SPWikiLoader
-from nominatim.tools.special_phrases.special_phrase import SpecialPhrase

nominatim/tools/special_phrases/sp_csv_loader.py

@@ -0,0 +1,54 @@
+"""
+    Module containing the SPCsvLoader class.
+
+    The class allows to load phrases from a csv file.
+"""
+import csv
+import os
+from nominatim.tools.special_phrases.special_phrase import SpecialPhrase
+from nominatim.tools.special_phrases.sp_loader import SPLoader
+from nominatim.errors import UsageError
+
+class SPCsvLoader(SPLoader):
+    """
+        Base class for special phrases loaders.
+        Handle the loading of special phrases from external sources.
+    """
+    def __init__(self, csv_path):
+        super().__init__()
+        self.csv_path = csv_path
+        self.has_been_read = False
+
+    def __next__(self):
+        if self.has_been_read:
+            raise StopIteration()
+
+        self.has_been_read = True
+        SPCsvLoader.check_csv_validity(self.csv_path)
+        return SPCsvLoader.parse_csv(self.csv_path)
+
+    @staticmethod
+    def parse_csv(csv_path):
+        """
+            Open and parse the given csv file.
+            Create the corresponding SpecialPhrases.
+        """
+        phrases = set()
+
+        with open(csv_path) as file:
+            reader = csv.DictReader(file, delimiter=',')
+            for row in reader:
+                phrases.add(
+                    SpecialPhrase(row['phrase'], row['class'], row['type'], row['operator'])
+                )
+        return phrases
+
+    @staticmethod
+    def check_csv_validity(csv_path):
+        """
+            Check that the csv file has the right extension.
+        """
+        _, extension = os.path.splitext(csv_path)
+
+        if extension != '.csv':
+            raise UsageError('The file {} is not a csv file.'.format(csv_path))

nominatim/tools/special_phrases/sp_wiki_loader.py

@@ -1,8 +1,8 @@
 """
     Module containing the SPWikiLoader class.
 """
-import logging
 import re
+import logging
 from nominatim.tools.special_phrases.special_phrase import SpecialPhrase
 from nominatim.tools.special_phrases.sp_loader import SPLoader
 from nominatim.tools.exec_utils import get_url