Source code for langchain.agents.output_parsers.react_json_single_input

import json
import re
from typing import Union

from langchain_core.agents import AgentAction, AgentFinish
from langchain_core.exceptions import OutputParserException

from langchain.agents.agent import AgentOutputParser
from langchain.agents.chat.prompt import FORMAT_INSTRUCTIONS

FINAL_ANSWER_ACTION = "Final Answer:"


[docs]class ReActJsonSingleInputOutputParser(AgentOutputParser): """Parses ReAct-style LLM calls that have a single tool input in json format. Expects output to be in one of two formats. If the output signals that an action should be taken, should be in the below format. This will result in an AgentAction being returned. ``` Thought: agent thought here Action: ``` { "action": "search", "action_input": "what is the temperature in SF" } ``` ``` If the output signals that a final answer should be given, should be in the below format. This will result in an AgentFinish being returned. ``` Thought: agent thought here Final Answer: The temperature is 100 degrees ``` """ pattern = re.compile(r"^.*?`{3}(?:json)?\n?(.*?)`{3}.*?$", re.DOTALL) """Regex pattern to parse the output."""
[docs] def get_format_instructions(self) -> str: return FORMAT_INSTRUCTIONS
[docs] def parse(self, text: str) -> Union[AgentAction, AgentFinish]: includes_answer = FINAL_ANSWER_ACTION in text try: found = self.pattern.search(text) if not found: # Fast fail to parse Final Answer. raise ValueError("action not found") action = found.group(1) response = json.loads(action.strip()) includes_action = "action" in response if includes_answer and includes_action: raise OutputParserException( "Parsing LLM output produced a final answer " f"and a parse-able action: {text}" ) return AgentAction( response["action"], response.get("action_input", {}), text ) except Exception: if not includes_answer: raise OutputParserException(f"Could not parse LLM output: {text}") output = text.split(FINAL_ANSWER_ACTION)[-1].strip() return AgentFinish({"output": output}, text)
@property def _type(self) -> str: return "react-json-single-input"