Langchain-Chatchat/server/agent/custom_template.py

from langchain.agents import Tool, AgentOutputParser
from langchain.prompts import StringPromptTemplate
from typing import List, Union
from langchain.schema import AgentAction, AgentFinish
import re

class CustomPromptTemplate(StringPromptTemplate):
    # The template to use
    template: str
    # The list of tools available
    tools: List[Tool]

    def format(self, **kwargs) -> str:
        # Get the intermediate steps (AgentAction, Observation tuples)
        # Format them in a particular way
        intermediate_steps = kwargs.pop("intermediate_steps")
        thoughts = ""
        for action, observation in intermediate_steps:
            thoughts += action.log
            thoughts += f"\nObservation: {observation}\nThought: "
        # Set the agent_scratchpad variable to that value
        kwargs["agent_scratchpad"] = thoughts
        # Create a tools variable from the list of tools provided
        kwargs["tools"] = "\n".join([f"{tool.name}: {tool.description}" for tool in self.tools])
        # Create a list of tool names for the tools provided
        kwargs["tool_names"] = ", ".join([tool.name for tool in self.tools])
        return self.template.format(**kwargs)
class CustomOutputParser(AgentOutputParser):

    def parse(self, llm_output: str) -> AgentFinish | AgentAction | str:
        # Check if agent should finish
        if "Final Answer:" in llm_output:
            return AgentFinish(
                # Return values is generally always a dictionary with a single `output` key
                # It is not recommended to try anything else at the moment :)
                return_values={"output": llm_output.replace("Final Answer:", "").strip()},
                log=llm_output,
            )
        # Parse out the action and action input
        regex = r"Action\s*\d*\s*:(.*?)\nAction\s*\d*\s*Input\s*\d*\s*:[\s]*(.*)"
        match = re.search(regex, llm_output, re.DOTALL)
        if not match:
            return AgentFinish(
                return_values={"output": f"调用agent失败: `{llm_output}`"},
                log=llm_output,
            )
        action = match.group(1).strip()
        action_input = match.group(2)
        # Return the action and action input
        try:
            ans = AgentAction(
            tool=action,
            tool_input=action_input.strip(" ").strip('"'),
            log=llm_output
            )
            return ans
        except:
            return AgentFinish(
                return_values={"output": f"调用agent失败: `{llm_output}`"},
                log=llm_output,
            )