126 lines
3.4 KiB
Python
126 lines
3.4 KiB
Python
import abc
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import struct
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import re
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from typing import Optional, Tuple
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class MQTTPayload(abc.ABC):
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FORMAT = ''
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PACKER = {}
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UNPACKER = {}
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def __init__(self, **kwargs):
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for field in self.__class__.__annotations__:
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setattr(self, field, kwargs[field])
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def pack(self):
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args = []
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bf_number = -1
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bf_arg = 0
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bf_progress = 0
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for field, field_type in self.__class__.__annotations__.items():
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bfp = _bit_field_params(field_type)
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if bfp:
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n, s, b = bfp
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if n != bf_number:
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if bf_number != -1:
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args.append(bf_arg)
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bf_number = n
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bf_progress = 0
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bf_arg = 0
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bf_arg |= (getattr(self, field) & (2 ** b - 1)) << bf_progress
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bf_progress += b
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else:
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if bf_number != -1:
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args.append(bf_arg)
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bf_number = -1
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bf_progress = 0
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bf_arg = 0
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args.append(self._pack_field(field))
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if bf_number != -1:
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args.append(bf_arg)
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return struct.pack(self.FORMAT, *args)
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@classmethod
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def unpack(cls, buf: bytes):
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data = struct.unpack(cls.FORMAT, buf)
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kwargs = {}
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i = 0
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bf_number = -1
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bf_progress = 0
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for field, field_type in cls.__annotations__.items():
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bfp = _bit_field_params(field_type)
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if bfp:
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n, s, b = bfp
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if n != bf_number:
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bf_number = n
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bf_progress = 0
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kwargs[field] = (data[i] >> bf_progress) & (2 ** b - 1)
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bf_progress += b
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continue # don't increment i
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if bf_number != -1:
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bf_number = -1
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i += 1
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if issubclass(field_type, MQTTPayloadCustomField):
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kwargs[field] = field_type.unpack(data[i])
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else:
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kwargs[field] = cls._unpack_field(field, data[i])
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i += 1
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return cls(**kwargs)
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def _pack_field(self, name):
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val = getattr(self, name)
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if self.PACKER and name in self.PACKER:
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return self.PACKER[name](val)
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else:
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return val
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@classmethod
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def _unpack_field(cls, name, val):
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if isinstance(val, MQTTPayloadCustomField):
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return
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if cls.UNPACKER and name in cls.UNPACKER:
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return cls.UNPACKER[name](val)
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else:
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return val
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class MQTTPayloadCustomField(abc.ABC):
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def __init__(self, **kwargs):
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for field in self.__class__.__annotations__:
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setattr(self, field, kwargs[field])
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@abc.abstractmethod
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def __index__(self):
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pass
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@classmethod
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@abc.abstractmethod
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def unpack(cls, *args, **kwargs):
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pass
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def bit_field(seq_no: int, total_bits: int, bits: int):
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return type(f'MQTTPayloadBitField_{seq_no}_{total_bits}_{bits}', (object,), {
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'seq_no': seq_no,
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'total_bits': total_bits,
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'bits': bits
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})
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def _bit_field_params(cl) -> Optional[Tuple[int, ...]]:
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match = re.match(r'MQTTPayloadBitField_(\d+)_(\d+)_(\d)$', cl.__name__)
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if match is not None:
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return tuple([int(match.group(i)) for i in range(1, 4)])
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return None
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