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569 lines
22 KiB
Python
569 lines
22 KiB
Python
"""Chain that takes in an input and produces an action and action input."""
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from __future__ import annotations
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import json
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import logging
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from abc import abstractmethod
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from pathlib import Path
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from typing import Any, Dict, List, Optional, Sequence, Tuple, Union
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import yaml
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from pydantic import BaseModel, root_validator
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from langchain.agents.tools import InvalidTool
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from langchain.callbacks.base import BaseCallbackManager
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from langchain.chains.base import Chain
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from langchain.chains.llm import LLMChain
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from langchain.input import get_color_mapping
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from langchain.llms.base import BaseLLM
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from langchain.prompts.base import BasePromptTemplate
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from langchain.prompts.few_shot import FewShotPromptTemplate
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from langchain.prompts.prompt import PromptTemplate
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from langchain.schema import AgentAction, AgentFinish, BaseMessage
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from langchain.tools.base import BaseTool
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logger = logging.getLogger()
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class Agent(BaseModel):
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"""Class responsible for calling the language model and deciding the action.
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This is driven by an LLMChain. The prompt in the LLMChain MUST include
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a variable called "agent_scratchpad" where the agent can put its
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intermediary work.
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"""
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llm_chain: LLMChain
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allowed_tools: Optional[List[str]] = None
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return_values: List[str] = ["output"]
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@abstractmethod
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def _extract_tool_and_input(self, text: str) -> Optional[Tuple[str, str]]:
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"""Extract tool and tool input from llm output."""
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def _fix_text(self, text: str) -> str:
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"""Fix the text."""
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raise ValueError("fix_text not implemented for this agent.")
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@property
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def _stop(self) -> List[str]:
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return [
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f"\n{self.observation_prefix.rstrip()}",
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f"\n\t{self.observation_prefix.rstrip()}",
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]
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def _construct_scratchpad(
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self, intermediate_steps: List[Tuple[AgentAction, str]]
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) -> Union[str, List[BaseMessage]]:
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"""Construct the scratchpad that lets the agent continue its thought process."""
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thoughts = ""
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for action, observation in intermediate_steps:
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thoughts += action.log
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thoughts += f"\n{self.observation_prefix}{observation}\n{self.llm_prefix}"
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return thoughts
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def _get_next_action(self, full_inputs: Dict[str, str]) -> AgentAction:
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full_output = self.llm_chain.predict(**full_inputs)
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parsed_output = self._extract_tool_and_input(full_output)
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while parsed_output is None:
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full_output = self._fix_text(full_output)
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full_inputs["agent_scratchpad"] += full_output
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output = self.llm_chain.predict(**full_inputs)
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full_output += output
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parsed_output = self._extract_tool_and_input(full_output)
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return AgentAction(
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tool=parsed_output[0], tool_input=parsed_output[1], log=full_output
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)
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async def _aget_next_action(self, full_inputs: Dict[str, str]) -> AgentAction:
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full_output = await self.llm_chain.apredict(**full_inputs)
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parsed_output = self._extract_tool_and_input(full_output)
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while parsed_output is None:
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full_output = self._fix_text(full_output)
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full_inputs["agent_scratchpad"] += full_output
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output = await self.llm_chain.apredict(**full_inputs)
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full_output += output
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parsed_output = self._extract_tool_and_input(full_output)
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return AgentAction(
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tool=parsed_output[0], tool_input=parsed_output[1], log=full_output
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)
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def plan(
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self, intermediate_steps: List[Tuple[AgentAction, str]], **kwargs: Any
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) -> Union[AgentAction, AgentFinish]:
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"""Given input, decided what to do.
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Args:
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intermediate_steps: Steps the LLM has taken to date,
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along with observations
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**kwargs: User inputs.
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Returns:
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Action specifying what tool to use.
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"""
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full_inputs = self.get_full_inputs(intermediate_steps, **kwargs)
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action = self._get_next_action(full_inputs)
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if action.tool == self.finish_tool_name:
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return AgentFinish({"output": action.tool_input}, action.log)
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return action
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async def aplan(
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self, intermediate_steps: List[Tuple[AgentAction, str]], **kwargs: Any
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) -> Union[AgentAction, AgentFinish]:
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"""Given input, decided what to do.
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Args:
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intermediate_steps: Steps the LLM has taken to date,
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along with observations
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**kwargs: User inputs.
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Returns:
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Action specifying what tool to use.
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"""
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full_inputs = self.get_full_inputs(intermediate_steps, **kwargs)
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action = await self._aget_next_action(full_inputs)
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if action.tool == self.finish_tool_name:
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return AgentFinish({"output": action.tool_input}, action.log)
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return action
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def get_full_inputs(
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self, intermediate_steps: List[Tuple[AgentAction, str]], **kwargs: Any
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) -> Dict[str, Any]:
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"""Create the full inputs for the LLMChain from intermediate steps."""
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thoughts = self._construct_scratchpad(intermediate_steps)
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new_inputs = {"agent_scratchpad": thoughts, "stop": self._stop}
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full_inputs = {**kwargs, **new_inputs}
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return full_inputs
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def prepare_for_new_call(self) -> None:
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"""Prepare the agent for new call, if needed."""
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pass
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@property
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def finish_tool_name(self) -> str:
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"""Name of the tool to use to finish the chain."""
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return "Final Answer"
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@property
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def input_keys(self) -> List[str]:
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"""Return the input keys.
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:meta private:
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"""
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return list(set(self.llm_chain.input_keys) - {"agent_scratchpad"})
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@root_validator()
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def validate_prompt(cls, values: Dict) -> Dict:
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"""Validate that prompt matches format."""
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prompt = values["llm_chain"].prompt
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if "agent_scratchpad" not in prompt.input_variables:
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logger.warning(
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"`agent_scratchpad` should be a variable in prompt.input_variables."
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" Did not find it, so adding it at the end."
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)
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prompt.input_variables.append("agent_scratchpad")
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if isinstance(prompt, PromptTemplate):
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prompt.template += "\n{agent_scratchpad}"
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elif isinstance(prompt, FewShotPromptTemplate):
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prompt.suffix += "\n{agent_scratchpad}"
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else:
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raise ValueError(f"Got unexpected prompt type {type(prompt)}")
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return values
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@property
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@abstractmethod
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def observation_prefix(self) -> str:
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"""Prefix to append the observation with."""
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@property
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@abstractmethod
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def llm_prefix(self) -> str:
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"""Prefix to append the LLM call with."""
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@classmethod
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@abstractmethod
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def create_prompt(cls, tools: Sequence[BaseTool]) -> BasePromptTemplate:
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"""Create a prompt for this class."""
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@classmethod
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def _validate_tools(cls, tools: Sequence[BaseTool]) -> None:
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"""Validate that appropriate tools are passed in."""
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pass
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@classmethod
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def from_llm_and_tools(
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cls,
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llm: BaseLLM,
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tools: Sequence[BaseTool],
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callback_manager: Optional[BaseCallbackManager] = None,
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**kwargs: Any,
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) -> Agent:
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"""Construct an agent from an LLM and tools."""
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cls._validate_tools(tools)
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llm_chain = LLMChain(
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llm=llm,
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prompt=cls.create_prompt(tools),
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callback_manager=callback_manager,
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)
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tool_names = [tool.name for tool in tools]
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return cls(llm_chain=llm_chain, allowed_tools=tool_names, **kwargs)
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def return_stopped_response(
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self,
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early_stopping_method: str,
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intermediate_steps: List[Tuple[AgentAction, str]],
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**kwargs: Any,
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) -> AgentFinish:
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"""Return response when agent has been stopped due to max iterations."""
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if early_stopping_method == "force":
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# `force` just returns a constant string
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return AgentFinish({"output": "Agent stopped due to max iterations."}, "")
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elif early_stopping_method == "generate":
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# Generate does one final forward pass
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thoughts = ""
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for action, observation in intermediate_steps:
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thoughts += action.log
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thoughts += (
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f"\n{self.observation_prefix}{observation}\n{self.llm_prefix}"
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)
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# Adding to the previous steps, we now tell the LLM to make a final pred
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thoughts += (
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"\n\nI now need to return a final answer based on the previous steps:"
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)
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new_inputs = {"agent_scratchpad": thoughts, "stop": self._stop}
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full_inputs = {**kwargs, **new_inputs}
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full_output = self.llm_chain.predict(**full_inputs)
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# We try to extract a final answer
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parsed_output = self._extract_tool_and_input(full_output)
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if parsed_output is None:
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# If we cannot extract, we just return the full output
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return AgentFinish({"output": full_output}, full_output)
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tool, tool_input = parsed_output
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if tool == self.finish_tool_name:
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# If we can extract, we send the correct stuff
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return AgentFinish({"output": tool_input}, full_output)
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else:
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# If we can extract, but the tool is not the final tool,
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# we just return the full output
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return AgentFinish({"output": full_output}, full_output)
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else:
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raise ValueError(
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"early_stopping_method should be one of `force` or `generate`, "
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f"got {early_stopping_method}"
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)
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@property
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@abstractmethod
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def _agent_type(self) -> str:
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"""Return Identifier of agent type."""
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def dict(self, **kwargs: Any) -> Dict:
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"""Return dictionary representation of agent."""
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_dict = super().dict()
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_dict["_type"] = self._agent_type
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return _dict
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def save(self, file_path: Union[Path, str]) -> None:
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"""Save the agent.
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Args:
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file_path: Path to file to save the agent to.
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Example:
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.. code-block:: python
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# If working with agent executor
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agent.agent.save(file_path="path/agent.yaml")
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"""
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# Convert file to Path object.
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if isinstance(file_path, str):
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save_path = Path(file_path)
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else:
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save_path = file_path
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directory_path = save_path.parent
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directory_path.mkdir(parents=True, exist_ok=True)
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# Fetch dictionary to save
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agent_dict = self.dict()
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if save_path.suffix == ".json":
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with open(file_path, "w") as f:
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json.dump(agent_dict, f, indent=4)
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elif save_path.suffix == ".yaml":
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with open(file_path, "w") as f:
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yaml.dump(agent_dict, f, default_flow_style=False)
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else:
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raise ValueError(f"{save_path} must be json or yaml")
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class AgentExecutor(Chain, BaseModel):
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"""Consists of an agent using tools."""
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agent: Agent
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tools: Sequence[BaseTool]
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return_intermediate_steps: bool = False
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max_iterations: Optional[int] = 15
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early_stopping_method: str = "force"
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@classmethod
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def from_agent_and_tools(
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cls,
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agent: Agent,
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tools: Sequence[BaseTool],
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callback_manager: Optional[BaseCallbackManager] = None,
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**kwargs: Any,
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) -> AgentExecutor:
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"""Create from agent and tools."""
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return cls(
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agent=agent, tools=tools, callback_manager=callback_manager, **kwargs
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)
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@root_validator()
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def validate_tools(cls, values: Dict) -> Dict:
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"""Validate that tools are compatible with agent."""
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agent = values["agent"]
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tools = values["tools"]
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if agent.allowed_tools is not None:
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if set(agent.allowed_tools) != set([tool.name for tool in tools]):
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raise ValueError(
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f"Allowed tools ({agent.allowed_tools}) different than "
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f"provided tools ({[tool.name for tool in tools]})"
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)
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return values
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def save(self, file_path: Union[Path, str]) -> None:
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"""Raise error - saving not supported for Agent Executors."""
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raise ValueError(
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"Saving not supported for agent executors. "
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"If you are trying to save the agent, please use the "
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"`.save_agent(...)`"
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)
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def save_agent(self, file_path: Union[Path, str]) -> None:
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"""Save the underlying agent."""
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return self.agent.save(file_path)
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@property
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def input_keys(self) -> List[str]:
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"""Return the input keys.
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:meta private:
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"""
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return self.agent.input_keys
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@property
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def output_keys(self) -> List[str]:
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"""Return the singular output key.
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:meta private:
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"""
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if self.return_intermediate_steps:
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return self.agent.return_values + ["intermediate_steps"]
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else:
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return self.agent.return_values
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def _should_continue(self, iterations: int) -> bool:
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if self.max_iterations is None:
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return True
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else:
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return iterations < self.max_iterations
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def _return(self, output: AgentFinish, intermediate_steps: list) -> Dict[str, Any]:
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self.callback_manager.on_agent_finish(
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output, color="green", verbose=self.verbose
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)
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final_output = output.return_values
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if self.return_intermediate_steps:
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final_output["intermediate_steps"] = intermediate_steps
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return final_output
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async def _areturn(
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self, output: AgentFinish, intermediate_steps: list
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) -> Dict[str, Any]:
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if self.callback_manager.is_async:
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await self.callback_manager.on_agent_finish(
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output, color="green", verbose=self.verbose
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)
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else:
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self.callback_manager.on_agent_finish(
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output, color="green", verbose=self.verbose
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)
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final_output = output.return_values
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if self.return_intermediate_steps:
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final_output["intermediate_steps"] = intermediate_steps
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return final_output
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def _take_next_step(
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self,
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name_to_tool_map: Dict[str, BaseTool],
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color_mapping: Dict[str, str],
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inputs: Dict[str, str],
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intermediate_steps: List[Tuple[AgentAction, str]],
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) -> Union[AgentFinish, Tuple[AgentAction, str]]:
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"""Take a single step in the thought-action-observation loop.
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Override this to take control of how the agent makes and acts on choices.
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"""
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# Call the LLM to see what to do.
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output = self.agent.plan(intermediate_steps, **inputs)
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# If the tool chosen is the finishing tool, then we end and return.
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if isinstance(output, AgentFinish):
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return output
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self.callback_manager.on_agent_action(
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output, verbose=self.verbose, color="green"
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)
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# Otherwise we lookup the tool
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if output.tool in name_to_tool_map:
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tool = name_to_tool_map[output.tool]
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return_direct = tool.return_direct
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color = color_mapping[output.tool]
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llm_prefix = "" if return_direct else self.agent.llm_prefix
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# We then call the tool on the tool input to get an observation
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observation = tool.run(
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output.tool_input,
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verbose=self.verbose,
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color=color,
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llm_prefix=llm_prefix,
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observation_prefix=self.agent.observation_prefix,
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)
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else:
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observation = InvalidTool().run(
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output.tool,
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verbose=self.verbose,
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color=None,
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llm_prefix="",
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observation_prefix=self.agent.observation_prefix,
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)
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return output, observation
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async def _atake_next_step(
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self,
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name_to_tool_map: Dict[str, BaseTool],
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color_mapping: Dict[str, str],
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inputs: Dict[str, str],
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intermediate_steps: List[Tuple[AgentAction, str]],
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) -> Union[AgentFinish, Tuple[AgentAction, str]]:
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"""Take a single step in the thought-action-observation loop.
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Override this to take control of how the agent makes and acts on choices.
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"""
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# Call the LLM to see what to do.
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output = await self.agent.aplan(intermediate_steps, **inputs)
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# If the tool chosen is the finishing tool, then we end and return.
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if isinstance(output, AgentFinish):
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return output
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if self.callback_manager.is_async:
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await self.callback_manager.on_agent_action(
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output, verbose=self.verbose, color="green"
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)
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else:
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self.callback_manager.on_agent_action(
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output, verbose=self.verbose, color="green"
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)
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# Otherwise we lookup the tool
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if output.tool in name_to_tool_map:
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tool = name_to_tool_map[output.tool]
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return_direct = tool.return_direct
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color = color_mapping[output.tool]
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llm_prefix = "" if return_direct else self.agent.llm_prefix
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# We then call the tool on the tool input to get an observation
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observation = await tool.arun(
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output.tool_input,
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verbose=self.verbose,
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color=color,
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llm_prefix=llm_prefix,
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observation_prefix=self.agent.observation_prefix,
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)
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else:
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observation = await InvalidTool().arun(
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output.tool,
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verbose=self.verbose,
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color=None,
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llm_prefix="",
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observation_prefix=self.agent.observation_prefix,
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)
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return_direct = False
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return output, observation
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def _call(self, inputs: Dict[str, str]) -> Dict[str, Any]:
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"""Run text through and get agent response."""
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# Do any preparation necessary when receiving a new input.
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self.agent.prepare_for_new_call()
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# Construct a mapping of tool name to tool for easy lookup
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name_to_tool_map = {tool.name: tool for tool in self.tools}
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# We construct a mapping from each tool to a color, used for logging.
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color_mapping = get_color_mapping(
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[tool.name for tool in self.tools], excluded_colors=["green"]
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)
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intermediate_steps: List[Tuple[AgentAction, str]] = []
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# Let's start tracking the iterations the agent has gone through
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iterations = 0
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# We now enter the agent loop (until it returns something).
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while self._should_continue(iterations):
|
|
next_step_output = self._take_next_step(
|
|
name_to_tool_map, color_mapping, inputs, intermediate_steps
|
|
)
|
|
if isinstance(next_step_output, AgentFinish):
|
|
return self._return(next_step_output, intermediate_steps)
|
|
|
|
intermediate_steps.append(next_step_output)
|
|
# See if tool should return directly
|
|
tool_return = self._get_tool_return(next_step_output)
|
|
if tool_return is not None:
|
|
return self._return(tool_return, intermediate_steps)
|
|
iterations += 1
|
|
output = self.agent.return_stopped_response(
|
|
self.early_stopping_method, intermediate_steps, **inputs
|
|
)
|
|
return self._return(output, intermediate_steps)
|
|
|
|
async def _acall(self, inputs: Dict[str, str]) -> Dict[str, str]:
|
|
"""Run text through and get agent response."""
|
|
# Do any preparation necessary when receiving a new input.
|
|
self.agent.prepare_for_new_call()
|
|
# Construct a mapping of tool name to tool for easy lookup
|
|
name_to_tool_map = {tool.name: tool for tool in self.tools}
|
|
# We construct a mapping from each tool to a color, used for logging.
|
|
color_mapping = get_color_mapping(
|
|
[tool.name for tool in self.tools], excluded_colors=["green"]
|
|
)
|
|
intermediate_steps: List[Tuple[AgentAction, str]] = []
|
|
# Let's start tracking the iterations the agent has gone through
|
|
iterations = 0
|
|
# We now enter the agent loop (until it returns something).
|
|
while self._should_continue(iterations):
|
|
next_step_output = await self._atake_next_step(
|
|
name_to_tool_map, color_mapping, inputs, intermediate_steps
|
|
)
|
|
if isinstance(next_step_output, AgentFinish):
|
|
return await self._areturn(next_step_output, intermediate_steps)
|
|
|
|
intermediate_steps.append(next_step_output)
|
|
# See if tool should return directly
|
|
tool_return = self._get_tool_return(next_step_output)
|
|
if tool_return is not None:
|
|
return await self._areturn(tool_return, intermediate_steps)
|
|
|
|
iterations += 1
|
|
output = self.agent.return_stopped_response(
|
|
self.early_stopping_method, intermediate_steps, **inputs
|
|
)
|
|
return await self._areturn(output, intermediate_steps)
|
|
|
|
def _get_tool_return(
|
|
self, next_step_output: Tuple[AgentAction, str]
|
|
) -> Optional[AgentFinish]:
|
|
"""Check if the tool is a returning tool."""
|
|
agent_action, observation = next_step_output
|
|
name_to_tool_map = {tool.name: tool for tool in self.tools}
|
|
# Invalid tools won't be in the map, so we return False.
|
|
if agent_action.tool in name_to_tool_map:
|
|
if name_to_tool_map[agent_action.tool].return_direct:
|
|
return AgentFinish(
|
|
{self.agent.return_values[0]: observation},
|
|
"",
|
|
)
|
|
return None
|