ccf189662d
git-subtree-dir: lib/dsmr_parser_lib git-subtree-mainline:4c0b801f96git-subtree-split:f9e188812f
58 lines
1.8 KiB
Python
58 lines
1.8 KiB
Python
import re
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class TelegramBuffer(object):
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"""
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Used as a buffer for a stream of telegram data. Constructs full telegram
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strings from the buffered data and returns it.
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"""
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def __init__(self):
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self._buffer = ''
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def get_all(self):
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"""
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Remove complete telegrams from buffer and yield them.
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:rtype generator:
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"""
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for telegram in self._find_telegrams():
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self._remove(telegram)
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yield telegram
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def append(self, data):
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"""
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Add telegram data to buffer.
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:param str data: chars, lines or full telegram strings of telegram data
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"""
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self._buffer += data
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def _remove(self, telegram):
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"""
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Remove telegram from buffer and incomplete data preceding it. This
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is easier than validating the data before adding it to the buffer.
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:param str telegram:
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:return:
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"""
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# Remove data leading up to the telegram and the telegram itself.
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index = self._buffer.index(telegram) + len(telegram)
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self._buffer = self._buffer[index:]
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def _find_telegrams(self):
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"""
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Find complete telegrams in buffer from start ('/') till ending
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checksum ('!AB12\r\n').
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:rtype: list
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"""
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# - Match all characters after start of telegram except for the start
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# itself again '^\/]+', which eliminates incomplete preceding telegrams.
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# - Do non greedy match using '?' so start is matched up to the first
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# checksum that's found.
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# - The checksum is optional '{0,4}' because not all telegram versions
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# support it.
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return re.findall(
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r'\/[^\/]+?\![A-F0-9]{0,4}\0?\r\n',
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self._buffer,
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re.DOTALL
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)
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