65 lines
1.7 KiB
Python
65 lines
1.7 KiB
Python
import struct
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from typing import Union, Generator, Any, SupportsBytes, List, Tuple
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from dataclasses import dataclass
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def _decode_varint(
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buffer: bytes, pos: int, signed: bool = False, result_type: type = int
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) -> Tuple[int, int]:
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result = 0
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shift = 0
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while 1:
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b = buffer[pos]
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result |= (b & 0x7F) << shift
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pos += 1
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if not (b & 0x80):
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result = result_type(result)
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return (result, pos)
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shift += 7
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if shift >= 64:
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raise ValueError("Too many bytes when decoding varint.")
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def packed(value: bytes, signed: bool = False, result_type: type = int) -> list:
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parsed = []
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pos = 0
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while pos < len(value):
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decoded, pos = _decode_varint(
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value, pos, signed=signed, result_type=result_type
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)
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parsed.append(decoded)
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return parsed
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@dataclass(frozen=True)
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class Field:
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number: int
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wire_type: int
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value: Any
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def fields(value: bytes) -> Generator[Field, None, None]:
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i = 0
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while i < len(value):
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num_wire, i = _decode_varint(value, i)
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print(num_wire, i)
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number = num_wire >> 3
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wire_type = num_wire & 0x7
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if wire_type == 0:
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decoded, i = _decode_varint(value, i)
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elif wire_type == 1:
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decoded, i = None, i + 4
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elif wire_type == 2:
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length, i = _decode_varint(value, i)
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decoded = value[i : i + length]
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i += length
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elif wire_type == 5:
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decoded, i = None, i + 2
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else:
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raise NotImplementedError(f"Wire type {wire_type}")
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# print(Field(number=number, wire_type=wire_type, value=decoded))
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yield Field(number=number, wire_type=wire_type, value=decoded)
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