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."""
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."""
class_name = serialized.get("name", serialized.get("id", ["<unknown>"])[-1])
print(f"\n\n\033[1m> Entering new {class_name} chain...\033[0m")
[docs] def on_chain_end(self, outputs: Dict[str, Any], **kwargs: Any) -> None:
"""Print out that we finished a chain."""
print("\n\033[1m> Finished chain.\033[0m")
[docs] def on_agent_action(
self, action: AgentAction, color: Optional[str] = None, **kwargs: Any
) -> Any:
"""Run on agent action."""
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 agent ends."""
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 agent end."""
print_text(finish.log, color=color or self.color, end="\n")