stdout.py — langchain Source File

Source Code

"""Tracers that print to the console."""

import json
from collections.abc import Callable
from typing import Any

from langchain_core.tracers.base import BaseTracer
from langchain_core.tracers.schemas import Run
from langchain_core.utils.input import get_bolded_text, get_colored_text

MILLISECONDS_IN_SECOND = 1000


def try_json_stringify(obj: Any, fallback: str) -> str:
    """Try to stringify an object to JSON.

    Args:
        obj: Object to stringify.
        fallback: Fallback string to return if the object cannot be stringified.

    Returns:
        A JSON string if the object can be stringified, otherwise the fallback string.
    """
    try:
        return json.dumps(obj, indent=2, ensure_ascii=False)
    except Exception:
        return fallback


def elapsed(run: Any) -> str:
    """Get the elapsed time of a run.

    Args:
        run: any object with a `start_time` and `end_time` attribute.

    Returns:
        A string with the elapsed time in seconds or milliseconds if time is less than a
            second.

    """
    elapsed_time = run.end_time - run.start_time
    seconds = elapsed_time.total_seconds()
    if seconds < 1:
        return f"{seconds * MILLISECONDS_IN_SECOND:.0f}ms"
    return f"{seconds:.2f}s"


class FunctionCallbackHandler(BaseTracer):
    """Tracer that calls a function with a single str parameter."""

    name: str = "function_callback_handler"
    """The name of the tracer.

    This is used to identify the tracer in the logs.
    """

    def __init__(self, function: Callable[[str], None], **kwargs: Any) -> None:
        """Create a `FunctionCallbackHandler`.

        Args:
// ... (146 more lines)