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:"


class ReActJsonSingleInputOutputParser(AgentOutputParser):
    """解析具有json格式中单个工具输入的ReAct风格LLM调用。

期望输出为以下两种格式之一。

如果输出信号表明应采取行动，则应采用以下格式。这将导致返回AgentAction。

```
Thought: agent thought here
Action:
```
{
    "action": "search",
    "action_input": "what is the temperature in SF"
}
```
```

如果输出信号表明应给出最终答案，则应采用以下格式。这将导致返回AgentFinish。

```
Thought: agent thought here
Final Answer: The temperature is 100 degrees
```"""

    pattern = re.compile(r"^.*?`{3}(?:json)?\n?(.*?)`{3}.*?$", re.DOTALL)
    """用于解析输出的正则表达式模式。"""

    def get_format_instructions(self) -> str:
        return FORMAT_INSTRUCTIONS

    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"