90 lines
3.1 KiB
JavaScript
90 lines
3.1 KiB
JavaScript
import { OutputParserException } from "@langchain/core/output_parsers";
|
|
import { AgentActionOutputParser } from "../types.js";
|
|
import { FORMAT_INSTRUCTIONS } from "./prompt.js";
|
|
export const FINAL_ANSWER_ACTION = "Final Answer:";
|
|
/**
|
|
* A class that extends the AgentActionOutputParser to parse the output of
|
|
* the ChatAgent in LangChain. It checks if the output text contains the
|
|
* final answer action or a JSON response, and parses it accordingly.
|
|
* @example
|
|
* ```typescript
|
|
* const prompt = ChatPromptTemplate.fromMessages([
|
|
* [
|
|
* "ai",
|
|
* `{PREFIX}
|
|
* {FORMAT_INSTRUCTIONS}
|
|
* {SUFFIX}`,
|
|
* ],
|
|
* ["human", "Question: {input}"],
|
|
* ]);
|
|
* const runnableAgent = RunnableSequence.from([
|
|
* {
|
|
* input: (i: { input: string; steps: AgentStep[] }) => i.input,
|
|
* agent_scratchpad: (i: { input: string; steps: AgentStep[] }) =>
|
|
* formatLogToString(i.steps),
|
|
* },
|
|
* prompt,
|
|
* new OpenAI({ temperature: 0 }),
|
|
* new ChatAgentOutputParser(),
|
|
* ]);
|
|
*
|
|
* const executor = AgentExecutor.fromAgentAndTools({
|
|
* agent: runnableAgent,
|
|
* tools: [new SerpAPI(), new Calculator()],
|
|
* });
|
|
*
|
|
* const result = await executor.invoke({
|
|
* input:
|
|
* "Who is Olivia Wilde's boyfriend? What is his current age raised to the 0.23 power?",
|
|
* });
|
|
* ```
|
|
*/
|
|
export class ChatAgentOutputParser extends AgentActionOutputParser {
|
|
constructor() {
|
|
super(...arguments);
|
|
Object.defineProperty(this, "lc_namespace", {
|
|
enumerable: true,
|
|
configurable: true,
|
|
writable: true,
|
|
value: ["langchain", "agents", "chat"]
|
|
});
|
|
}
|
|
/**
|
|
* Parses the output text from the MRKL chain into an agent action or
|
|
* agent finish. If the text contains the final answer action or does not
|
|
* contain an action, it returns an AgentFinish with the output and log.
|
|
* If the text contains a JSON response, it returns the tool, toolInput,
|
|
* and log.
|
|
* @param text The output text from the MRKL chain.
|
|
* @returns An object that satisfies the AgentFinish interface or an object with the tool, toolInput, and log.
|
|
*/
|
|
async parse(text) {
|
|
if (text.includes(FINAL_ANSWER_ACTION) || !text.includes(`"action":`)) {
|
|
const parts = text.split(FINAL_ANSWER_ACTION);
|
|
const output = parts[parts.length - 1].trim();
|
|
return { returnValues: { output }, log: text };
|
|
}
|
|
const action = text.includes("```")
|
|
? text.trim().split(/```(?:json)?/)[1]
|
|
: text.trim();
|
|
try {
|
|
const response = JSON.parse(action.trim());
|
|
return {
|
|
tool: response.action,
|
|
toolInput: response.action_input,
|
|
log: text,
|
|
};
|
|
}
|
|
catch {
|
|
throw new OutputParserException(`Unable to parse JSON response from chat agent.\n\n${text}`);
|
|
}
|
|
}
|
|
/**
|
|
* Returns the format instructions used in the output parser for the
|
|
* ChatAgent class.
|
|
* @returns The format instructions as a string.
|
|
*/
|
|
getFormatInstructions() {
|
|
return FORMAT_INSTRUCTIONS;
|
|
}
|
|
}
|