Add 'lib/dsmr_parser_lib/' from commit 'f9e188812fbaee90974a3cddf201bbb40278fd9a'

git-subtree-dir: lib/dsmr_parser_lib
git-subtree-mainline: 4c0b801f96
git-subtree-split: f9e188812f

lib/dsmr_parser_lib/dsmr_parser/clients/telegram_buffer.py

@@ -0,0 +1,57 @@
+import re
+
+
+class TelegramBuffer(object):
+    """
+    Used as a buffer for a stream of telegram data. Constructs full telegram
+    strings from the buffered data and returns it.
+    """
+
+    def __init__(self):
+        self._buffer = ''
+
+    def get_all(self):
+        """
+        Remove complete telegrams from buffer and yield them.
+        :rtype generator:
+        """
+        for telegram in self._find_telegrams():
+            self._remove(telegram)
+            yield telegram
+
+    def append(self, data):
+        """
+        Add telegram data to buffer.
+        :param str data: chars, lines or full telegram strings of telegram data
+        """
+        self._buffer += data
+
+    def _remove(self, telegram):
+        """
+        Remove telegram from buffer and incomplete data preceding it. This
+        is easier than validating the data before adding it to the buffer.
+        :param str telegram:
+        :return:
+        """
+        # Remove data leading up to the telegram and the telegram itself.
+        index = self._buffer.index(telegram) + len(telegram)
+
+        self._buffer = self._buffer[index:]
+
+    def _find_telegrams(self):
+        """
+        Find complete telegrams in buffer from  start ('/') till ending
+        checksum ('!AB12\r\n').
+        :rtype: list
+        """
+        # - Match all characters after start of telegram except for the start
+        # itself again '^\/]+', which eliminates incomplete preceding telegrams.
+        # - Do non greedy match using '?' so start is matched up to the first
+        # checksum that's found.
+        # - The checksum is optional '{0,4}' because not all telegram versions
+        # support it.
+        return re.findall(
+            r'\/[^\/]+?\![A-F0-9]{0,4}\0?\r\n',
+            self._buffer,
+            re.DOTALL
+        )