redis_008.py

    def _read_length(self, f: BinaryIO) -> int:
        """Read a length-encoded integer"""
        first_byte = f.read(1)[0]

        # Check the first two bits (00, 01, 10, 11)
        bits = first_byte >> 6

        if bits == 0:  # 00xxxxxx
            return first_byte & 0x3F
        elif bits == 1:  # 01xxxxxx
            next_byte = f.read(1)[0]
            return ((first_byte & 0x3F) << 8) | next_byte
        elif bits == 2:  # 10xxxxxx
            # Discard the remaining 6 bits and read a 32-bit integer
            return struct.unpack(">I", f.read(4))[0]
        else:  # 11xxxxxx
            remaining = first_byte & 0x3F
            if remaining == 0:  # Read 8 bit integer
                return struct.unpack("B", f.read(1))[0]
            elif remaining == 1:  # Read 16 bit integer
                return struct.unpack(">H", f.read(2))[0]
            elif remaining == 2:  # Read 32 bit integer
                return struct.unpack(">I", f.read(4))[0]
            else:
                raise ValueError(f"Invalid length encoding: {first_byte}")