101 lines
3.6 KiB
JavaScript
101 lines
3.6 KiB
JavaScript
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import { BaseOutputParser, OutputParserException, } from "@langchain/core/output_parsers";
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import { LLMChain } from "../chains/llm_chain.js";
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import { NAIVE_FIX_PROMPT } from "./prompts.js";
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function isLLMChain(x) {
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return (x.prompt !== undefined && x.llm !== undefined);
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}
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/**
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* Class that extends the BaseOutputParser to handle situations where the
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* initial parsing attempt fails. It contains a retryChain for retrying
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* the parsing process in case of a failure.
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*/
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export class OutputFixingParser extends BaseOutputParser {
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static lc_name() {
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return "OutputFixingParser";
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}
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/**
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* Static method to create a new instance of OutputFixingParser using a
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* given language model, parser, and optional fields.
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* @param llm The language model to be used.
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* @param parser The parser to be used.
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* @param fields Optional fields which may contain a prompt.
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* @returns A new instance of OutputFixingParser.
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*/
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static fromLLM(llm, parser, fields) {
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const prompt = fields?.prompt ?? NAIVE_FIX_PROMPT;
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const chain = new LLMChain({ llm, prompt });
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return new OutputFixingParser({ parser, retryChain: chain });
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}
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constructor({ parser, retryChain, }) {
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super(...arguments);
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Object.defineProperty(this, "lc_namespace", {
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enumerable: true,
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configurable: true,
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writable: true,
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value: ["langchain", "output_parsers", "fix"]
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});
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Object.defineProperty(this, "lc_serializable", {
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enumerable: true,
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configurable: true,
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writable: true,
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value: true
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});
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Object.defineProperty(this, "parser", {
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enumerable: true,
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configurable: true,
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writable: true,
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value: void 0
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});
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Object.defineProperty(this, "retryChain", {
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enumerable: true,
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configurable: true,
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writable: true,
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value: void 0
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});
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this.parser = parser;
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this.retryChain = retryChain;
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}
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/**
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* Method to parse the completion using the parser. If the initial parsing
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* fails, it uses the retryChain to attempt to fix the output and retry
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* the parsing process.
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* @param completion The completion to be parsed.
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* @param callbacks Optional callbacks to be used during parsing.
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* @returns The parsed output.
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*/
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async parse(completion, callbacks) {
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try {
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return await this.parser.parse(completion, callbacks);
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}
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catch (e) {
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// eslint-disable-next-line no-instanceof/no-instanceof
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if (e instanceof OutputParserException) {
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const retryInput = {
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instructions: this.parser.getFormatInstructions(),
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completion,
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error: e,
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};
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if (isLLMChain(this.retryChain)) {
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const result = await this.retryChain.call(retryInput, callbacks);
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const newCompletion = result[this.retryChain.outputKey];
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return this.parser.parse(newCompletion, callbacks);
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}
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else {
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const result = await this.retryChain.invoke(retryInput, {
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callbacks,
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});
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return result;
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}
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}
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throw e;
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}
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}
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/**
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* Method to get the format instructions for the parser.
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* @returns The format instructions for the parser.
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*/
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getFormatInstructions() {
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return this.parser.getFormatInstructions();
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}
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}
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