ScoreStringResultOutputParser Class — langchain Architecture

Source Code

libs/langchain/langchain_classic/evaluation/scoring/eval_chain.py lines 100–147

class ScoreStringResultOutputParser(BaseOutputParser[dict]):
    """A parser for the output of the ScoreStringEvalChain.

    Attributes:
        _type: The type of the output parser.

    """

    @property
    def _type(self) -> str:
        """Return the type of the output parser.

        Returns:
            The type of the output parser.

        """
        return "pairwise_string_result"

    def parse(self, text: str) -> dict[str, Any]:
        """Parse the output text.

        Args:
            text: The output text to parse.

        Returns:
            The parsed output.

        Raises:
            ValueError: If the verdict is invalid.

        """
        match = _FIND_DOUBLE_BRACKETS.search(text)

        if match:
            verdict = match.group(1)

        if not match or verdict not in [*list("123456789"), "10"]:
            msg = (
                f"Invalid output: {text}. "
                "Output must contain a double bracketed string\
                 with the verdict between 1 and 10."
            )
            raise ValueError(msg)

        return {
            "reasoning": text,
            "score": int(verdict),
        }