added file tail reader

dsmr_parser/clients/filereader.py

@@ -1,5 +1,6 @@
 import logging
 import fileinput
+import tailer
 
 from dsmr_parser.clients.telegram_buffer import TelegramBuffer
 from dsmr_parser.exceptions import ParseError, InvalidChecksumError
@@ -120,3 +121,31 @@ class FileInputReader(object):
                         logger.warning(str(e))
                     except ParseError as e:
                         logger.error('Failed to parse telegram: %s', e)
+
+
+class FileTailReader(object):
+
+    def __init__(self, file, telegram_specification):
+        self._file = file
+        self.telegram_parser = TelegramParser(telegram_specification)
+        self.telegram_buffer = TelegramBuffer()
+        self.telegram_specification = telegram_specification
+
+    def read_as_object(self):
+        """
+        Read complete DSMR telegram's from a files tail and return a Telegram object.
+        :rtype: generator
+        """
+        with open(self._file,"rb") as file_handle:
+            for data in tailer.follow(file_handle):
+                str = data.decode()
+                self.telegram_buffer.append(str)
+
+                for telegram in self.telegram_buffer.get_all():
+                    try:
+                        yield Telegram(telegram, self.telegram_parser, self.telegram_specification)
+                    except dsmr_parser.exceptions.InvalidChecksumError as e:
+                        logger.warning(str(e))
+                    except dsmr_parser.exceptions.ParseError as e:
+                        logger.error('Failed to parse telegram: %s', e)
+