Class StreamReader

src/websockets/streams.py:6–151

Generator-based stream reader. This class doesn't support concurrent calls to :meth:`read_line`, :meth:`read_exact`, or :meth:`read_to_eof`. Make sure calls are serialized.

class StreamReader:
    """
    Generator-based stream reader.

    This class doesn't support concurrent calls to :meth:`read_line`,
    :meth:`read_exact`, or :meth:`read_to_eof`. Make sure calls are
    serialized.

    """

    def __init__(self) -> None:
        self.buffer = bytearray()
        self.eof = False

    def read_line(self, m: int) -> Generator[None, None, bytearray]:
        """
        Read a LF-terminated line from the stream.

        This is a generator-based coroutine.

        The return value includes the LF character.

        Args:
            m: Maximum number bytes to read; this is a security limit.

        Raises:
            EOFError: If the stream ends without a LF.
            RuntimeError: If the stream ends in more than ``m`` bytes.

        """
        n = 0  # number of bytes to read
        p = 0  # number of bytes without a newline
        while True:
            n = self.buffer.find(b"\n", p) + 1
            if n > 0:
                break
            p = len(self.buffer)
            if p > m:
                raise RuntimeError(f"read {p} bytes, expected no more than {m} bytes")
            if self.eof:
                raise EOFError(f"stream ends after {p} bytes, before end of line")
            yield
        if n > m:
            raise RuntimeError(f"read {n} bytes, expected no more than {m} bytes")
        r = self.buffer[:n]
        del self.buffer[:n]
        return r

    def read_exact(self, n: int) -> Generator[None, None, bytearray]:
        """
        Read a given number of bytes from the stream.

        This is a generator-based coroutine.

        Args:
            n: How many bytes to read.

        Raises: