@langchain/core
Version:
Core LangChain.js abstractions and schemas
237 lines (236 loc) • 8.4 kB
JavaScript
import { OutputParserException } from "./base.js";
import { BaseTransformOutputParser } from "./transform.js";
/**
* Class to parse the output of an LLM call to a list.
* @augments BaseOutputParser
*/
export class ListOutputParser extends BaseTransformOutputParser {
constructor() {
super(...arguments);
Object.defineProperty(this, "re", {
enumerable: true,
configurable: true,
writable: true,
value: void 0
});
}
async *_transform(inputGenerator) {
let buffer = "";
for await (const input of inputGenerator) {
if (typeof input === "string") {
// add current chunk to buffer
buffer += input;
}
else {
// extract message content and add to buffer
buffer += input.content;
}
// get parts in buffer
if (!this.re) {
const parts = await this.parse(buffer);
if (parts.length > 1) {
// if there are multiple parts, yield all but the last one
for (const part of parts.slice(0, -1)) {
yield [part];
}
// keep the last part in the buffer
buffer = parts[parts.length - 1];
}
}
else {
// if there is a regex, get all matches
const matches = [...buffer.matchAll(this.re)];
if (matches.length > 1) {
let doneIdx = 0;
// if there are multiple matches, yield all but the last one
for (const match of matches.slice(0, -1)) {
yield [match[1]];
doneIdx += (match.index ?? 0) + match[0].length;
}
// keep the last match in the buffer
buffer = buffer.slice(doneIdx);
}
}
}
// yield the last part
for (const part of await this.parse(buffer)) {
yield [part];
}
}
}
/**
* Class to parse the output of an LLM call as a comma-separated list.
* @augments ListOutputParser
*/
export class CommaSeparatedListOutputParser extends ListOutputParser {
constructor() {
super(...arguments);
Object.defineProperty(this, "lc_namespace", {
enumerable: true,
configurable: true,
writable: true,
value: ["langchain_core", "output_parsers", "list"]
});
Object.defineProperty(this, "lc_serializable", {
enumerable: true,
configurable: true,
writable: true,
value: true
});
}
static lc_name() {
return "CommaSeparatedListOutputParser";
}
/**
* Parses the given text into an array of strings, using a comma as the
* separator. If the parsing fails, throws an OutputParserException.
* @param text The text to parse.
* @returns An array of strings obtained by splitting the input text at each comma.
*/
async parse(text) {
try {
return text
.trim()
.split(",")
.map((s) => s.trim());
}
catch (e) {
throw new OutputParserException(`Could not parse output: ${text}`, text);
}
}
/**
* Provides instructions on the expected format of the response for the
* CommaSeparatedListOutputParser.
* @returns A string containing instructions on the expected format of the response.
*/
getFormatInstructions() {
return `Your response should be a list of comma separated values, eg: \`foo, bar, baz\``;
}
}
/**
* Class to parse the output of an LLM call to a list with a specific length and separator.
* @augments ListOutputParser
*/
export class CustomListOutputParser extends ListOutputParser {
constructor({ length, separator }) {
super(...arguments);
Object.defineProperty(this, "lc_namespace", {
enumerable: true,
configurable: true,
writable: true,
value: ["langchain_core", "output_parsers", "list"]
});
Object.defineProperty(this, "length", {
enumerable: true,
configurable: true,
writable: true,
value: void 0
});
Object.defineProperty(this, "separator", {
enumerable: true,
configurable: true,
writable: true,
value: void 0
});
this.length = length;
this.separator = separator || ",";
}
/**
* Parses the given text into an array of strings, using the specified
* separator. If the parsing fails or the number of items in the list
* doesn't match the expected length, throws an OutputParserException.
* @param text The text to parse.
* @returns An array of strings obtained by splitting the input text at each occurrence of the specified separator.
*/
async parse(text) {
try {
const items = text
.trim()
.split(this.separator)
.map((s) => s.trim());
if (this.length !== undefined && items.length !== this.length) {
throw new OutputParserException(`Incorrect number of items. Expected ${this.length}, got ${items.length}.`);
}
return items;
}
catch (e) {
if (Object.getPrototypeOf(e) === OutputParserException.prototype) {
throw e;
}
throw new OutputParserException(`Could not parse output: ${text}`);
}
}
/**
* Provides instructions on the expected format of the response for the
* CustomListOutputParser, including the number of items and the
* separator.
* @returns A string containing instructions on the expected format of the response.
*/
getFormatInstructions() {
return `Your response should be a list of ${this.length === undefined ? "" : `${this.length} `}items separated by "${this.separator}" (eg: \`foo${this.separator} bar${this.separator} baz\`)`;
}
}
export class NumberedListOutputParser extends ListOutputParser {
constructor() {
super(...arguments);
Object.defineProperty(this, "lc_namespace", {
enumerable: true,
configurable: true,
writable: true,
value: ["langchain_core", "output_parsers", "list"]
});
Object.defineProperty(this, "lc_serializable", {
enumerable: true,
configurable: true,
writable: true,
value: true
});
Object.defineProperty(this, "re", {
enumerable: true,
configurable: true,
writable: true,
value: /\d+\.\s([^\n]+)/g
});
}
static lc_name() {
return "NumberedListOutputParser";
}
getFormatInstructions() {
return `Your response should be a numbered list with each item on a new line. For example: \n\n1. foo\n\n2. bar\n\n3. baz`;
}
async parse(text) {
return [...(text.matchAll(this.re) ?? [])].map((m) => m[1]);
}
}
export class MarkdownListOutputParser extends ListOutputParser {
constructor() {
super(...arguments);
Object.defineProperty(this, "lc_namespace", {
enumerable: true,
configurable: true,
writable: true,
value: ["langchain_core", "output_parsers", "list"]
});
Object.defineProperty(this, "lc_serializable", {
enumerable: true,
configurable: true,
writable: true,
value: true
});
Object.defineProperty(this, "re", {
enumerable: true,
configurable: true,
writable: true,
value: /^\s*[-*]\s([^\n]+)$/gm
});
}
static lc_name() {
return "NumberedListOutputParser";
}
getFormatInstructions() {
return `Your response should be a numbered list with each item on a new line. For example: \n\n1. foo\n\n2. bar\n\n3. baz`;
}
async parse(text) {
return [...(text.matchAll(this.re) ?? [])].map((m) => m[1]);
}
}