68 lines
2.0 KiB
Python
68 lines
2.0 KiB
Python
from .struct import Struct
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from .types import (
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Int8, Int16, Int32, Int64, Bytes, String, Array, Schema, AbstractType
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)
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from ..util import crc32
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class Message(Struct):
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SCHEMA = Schema(
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('crc', Int32),
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('magic', Int8),
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('attributes', Int8),
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('key', Bytes),
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('value', Bytes)
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)
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def __init__(self, value, key=None, magic=0, attributes=0, crc=0):
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self.crc = crc
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self.magic = magic
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self.attributes = attributes
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self.key = key
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self.value = value
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self.encode = self._encode_self
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def _encode_self(self, recalc_crc=True):
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message = Message.SCHEMA.encode(
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(self.crc, self.magic, self.attributes, self.key, self.value)
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)
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if not recalc_crc:
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return message
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self.crc = crc32(message[4:])
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return self.SCHEMA.fields[0].encode(self.crc) + message[4:]
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class MessageSet(AbstractType):
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ITEM = Schema(
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('offset', Int64),
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('message_size', Int32),
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('message', Message.SCHEMA)
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)
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@classmethod
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def encode(cls, items, size=True, recalc_message_size=True):
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encoded_values = []
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for (offset, message_size, message) in items:
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if isinstance(message, Message):
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encoded_message = message.encode()
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else:
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encoded_message = cls.ITEM.fields[2].encode(message)
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if recalc_message_size:
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message_size = len(encoded_message)
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encoded_values.append(cls.ITEM.fields[0].encode(offset))
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encoded_values.append(cls.ITEM.fields[1].encode(message_size))
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encoded_values.append(encoded_message)
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encoded = b''.join(encoded_values)
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if not size:
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return encoded
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return Int32.encode(len(encoded)) + encoded
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@classmethod
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def decode(cls, data):
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size = Int32.decode(data)
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end = data.tell() + size
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items = []
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while data.tell() < end:
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items.append(cls.ITEM.decode(data))
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return items
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