MessageStream Class — anthropic-sdk-python Architecture

Source Code

src/anthropic/lib/streaming/_messages.py lines 33–143

class MessageStream(Generic[ResponseFormatT]):
    text_stream: Iterator[str]
    """Iterator over just the text deltas in the stream.

    ```py
    for text in stream.text_stream:
        print(text, end="", flush=True)
    print()
    ```
    """

    def __init__(
        self,
        raw_stream: Stream[RawMessageStreamEvent],
        output_format: ResponseFormatT | NotGiven,
    ) -> None:
        self._raw_stream = raw_stream
        self.text_stream = self.__stream_text__()
        self._iterator = self.__stream__()
        self.__final_message_snapshot: ParsedMessage[ResponseFormatT] | None = None
        self.__output_format = output_format

    @property
    def response(self) -> httpx.Response:
        return self._raw_stream.response

    @property
    def request_id(self) -> str | None:
        return self.response.headers.get("request-id")  # type: ignore[no-any-return]

    def __next__(self) -> ParsedMessageStreamEvent[ResponseFormatT]:
        return self._iterator.__next__()

    def __iter__(self) -> Iterator[ParsedMessageStreamEvent[ResponseFormatT]]:
        for item in self._iterator:
            yield item

    def __enter__(self) -> Self:
        return self

    def __exit__(
        self,
        exc_type: type[BaseException] | None,
        exc: BaseException | None,
        exc_tb: TracebackType | None,
    ) -> None:
        self.close()

    def close(self) -> None:
        """
        Close the response and release the connection.

        Automatically called if the response body is read to completion.
        """
        self._raw_stream.close()

    def get_final_message(self) -> ParsedMessage[ResponseFormatT]:
        """Waits until the stream has been read to completion and returns
        the accumulated `Message` object.
        """
        self.until_done()
        assert self.__final_message_snapshot is not None
        return self.__final_message_snapshot

    def get_final_text(self) -> str:
        """Returns all `text` content blocks concatenated together.

        > [!NOTE]
        > Currently the API will only respond with a single content block.

        Will raise an error if no `text` content blocks were returned.
        """
        message = self.get_final_message()
        text_blocks: list[str] = []
        for block in message.content:
            if block.type == "text":
                text_blocks.append(block.text)

        if not text_blocks:
            raise RuntimeError(
                f".get_final_text() can only be called when the API returns a `text` content block.\nThe API returned {','.join([b.type for b in message.content])} content block type(s) that you can access by calling get_final_message().content"