Source code for langchain_core.callbacks.stdout
"""Callback Handler that prints to std out."""
from __future__ import annotations
from typing import TYPE_CHECKING, Any, Dict, Optional
from langchain_core.callbacks.base import BaseCallbackHandler
from langchain_core.utils import print_text
if TYPE_CHECKING:
from langchain_core.agents import AgentAction, AgentFinish
[docs]class StdOutCallbackHandler(BaseCallbackHandler):
"""Callback Handler that prints to std out."""
[docs] def __init__(self, color: Optional[str] = None) -> None:
"""Initialize callback handler.
Args:
color: The color to use for the text. Defaults to None.
"""
self.color = color
[docs] def on_chain_start(
self, serialized: Dict[str, Any], inputs: Dict[str, Any], **kwargs: Any
) -> None:
"""Print out that we are entering a chain.
Args:
serialized (Dict[str, Any]): The serialized chain.
inputs (Dict[str, Any]): The inputs to the chain.
**kwargs (Any): Additional keyword arguments.
"""
class_name = serialized.get("name", serialized.get("id", ["<unknown>"])[-1])
print(f"\n\n\033[1m> Entering new {class_name} chain...\033[0m") # noqa: T201
[docs] def on_chain_end(self, outputs: Dict[str, Any], **kwargs: Any) -> None:
"""Print out that we finished a chain.
Args:
outputs (Dict[str, Any]): The outputs of the chain.
**kwargs (Any): Additional keyword arguments.
"""
print("\n\033[1m> Finished chain.\033[0m") # noqa: T201
[docs] def on_agent_action(
self, action: AgentAction, color: Optional[str] = None, **kwargs: Any
) -> Any:
"""Run on agent action.
Args:
action (AgentAction): The agent action.
color (Optional[str]): The color to use for the text. Defaults to None.
**kwargs (Any): Additional keyword arguments.
"""
print_text(action.log, color=color or self.color)
[docs] def on_text(
self,
text: str,
color: Optional[str] = None,
end: str = "",
**kwargs: Any,
) -> None:
"""Run when the agent ends.
Args:
text (str): The text to print.
color (Optional[str]): The color to use for the text. Defaults to None.
end (str): The end character to use. Defaults to "".
**kwargs (Any): Additional keyword arguments.
"""
print_text(text, color=color or self.color, end=end)
[docs] def on_agent_finish(
self, finish: AgentFinish, color: Optional[str] = None, **kwargs: Any
) -> None:
"""Run on the agent end.
Args:
finish (AgentFinish): The agent finish.
color (Optional[str]): The color to use for the text. Defaults to None.
**kwargs (Any): Additional keyword arguments.
"""
print_text(finish.log, color=color or self.color, end="\n")