@langchain/core
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Core LangChain.js abstractions and schemas
345 lines (343 loc) • 12.1 kB
JavaScript
import { __export } from "../_virtual/rolldown_runtime.js";
import { ToolMessage, isDirectToolOutput } from "../messages/tool.js";
import { ToolInputParsingException, _configHasToolCallId, _isToolCall } from "./utils.js";
import { CallbackManager, parseCallbackConfigArg } from "../callbacks/manager.js";
import { AsyncLocalStorageProviderSingleton } from "../singletons/async_local_storage/index.js";
import "../singletons/index.js";
import { ensureConfig, mergeConfigs, patchConfig, pickRunnableConfigKeys } from "../runnables/config.js";
import { getAbortSignalError } from "../utils/signal.js";
import { interopParseAsync, isInteropZodError, isInteropZodSchema, isSimpleStringZodSchema } from "../utils/types/zod.js";
import { validatesOnlyStrings } from "../utils/json_schema.js";
import { BaseLangChain } from "../language_models/base.js";
import { isLangChainTool, isRunnableToolLike, isStructuredTool, isStructuredToolParams } from "./types.js";
import { z } from "zod/v3";
import { validate } from "@cfworker/json-schema";
import { z as z$1 } from "zod/v4";
//#region src/tools/index.ts
var tools_exports = {};
__export(tools_exports, {
BaseToolkit: () => BaseToolkit,
DynamicStructuredTool: () => DynamicStructuredTool,
DynamicTool: () => DynamicTool,
StructuredTool: () => StructuredTool,
Tool: () => Tool,
ToolInputParsingException: () => ToolInputParsingException,
isLangChainTool: () => isLangChainTool,
isRunnableToolLike: () => isRunnableToolLike,
isStructuredTool: () => isStructuredTool,
isStructuredToolParams: () => isStructuredToolParams,
tool: () => tool
});
/**
* Base class for Tools that accept input of any shape defined by a Zod schema.
*/
var StructuredTool = class extends BaseLangChain {
/**
* Optional provider-specific extra fields for the tool.
*
* This is used to pass provider-specific configuration that doesn't fit into
* standard tool fields.
*/
extras;
/**
* Whether to return the tool's output directly.
*
* Setting this to true means that after the tool is called,
* an agent should stop looping.
*/
returnDirect = false;
verboseParsingErrors = false;
get lc_namespace() {
return ["langchain", "tools"];
}
/**
* The tool response format.
*
* If "content" then the output of the tool is interpreted as the contents of a
* ToolMessage. If "content_and_artifact" then the output is expected to be a
* two-tuple corresponding to the (content, artifact) of a ToolMessage.
*
* @default "content"
*/
responseFormat = "content";
/**
* Default config object for the tool runnable.
*/
defaultConfig;
constructor(fields) {
super(fields ?? {});
this.verboseParsingErrors = fields?.verboseParsingErrors ?? this.verboseParsingErrors;
this.responseFormat = fields?.responseFormat ?? this.responseFormat;
this.defaultConfig = fields?.defaultConfig ?? this.defaultConfig;
this.metadata = fields?.metadata ?? this.metadata;
this.extras = fields?.extras ?? this.extras;
}
/**
* Invokes the tool with the provided input and configuration.
* @param input The input for the tool.
* @param config Optional configuration for the tool.
* @returns A Promise that resolves with the tool's output.
*/
async invoke(input, config) {
let toolInput;
let enrichedConfig = ensureConfig(mergeConfigs(this.defaultConfig, config));
if (_isToolCall(input)) {
toolInput = input.args;
enrichedConfig = {
...enrichedConfig,
toolCall: input
};
} else toolInput = input;
return this.call(toolInput, enrichedConfig);
}
/**
* @deprecated Use .invoke() instead. Will be removed in 0.3.0.
*
* Calls the tool with the provided argument, configuration, and tags. It
* parses the input according to the schema, handles any errors, and
* manages callbacks.
* @param arg The input argument for the tool.
* @param configArg Optional configuration or callbacks for the tool.
* @param tags Optional tags for the tool.
* @returns A Promise that resolves with a string.
*/
async call(arg, configArg, tags) {
const inputForValidation = _isToolCall(arg) ? arg.args : arg;
let parsed;
if (isInteropZodSchema(this.schema)) try {
parsed = await interopParseAsync(this.schema, inputForValidation);
} catch (e) {
let message = `Received tool input did not match expected schema`;
if (this.verboseParsingErrors) message = `${message}\nDetails: ${e.message}`;
if (isInteropZodError(e)) message = `${message}\n\n${z$1.prettifyError(e)}`;
throw new ToolInputParsingException(message, JSON.stringify(arg));
}
else {
const result$1 = validate(inputForValidation, this.schema);
if (!result$1.valid) {
let message = `Received tool input did not match expected schema`;
if (this.verboseParsingErrors) message = `${message}\nDetails: ${result$1.errors.map((e) => `${e.keywordLocation}: ${e.error}`).join("\n")}`;
throw new ToolInputParsingException(message, JSON.stringify(arg));
}
parsed = inputForValidation;
}
const config = parseCallbackConfigArg(configArg);
const callbackManager_ = CallbackManager.configure(config.callbacks, this.callbacks, config.tags || tags, this.tags, config.metadata, this.metadata, { verbose: this.verbose });
const runManager = await callbackManager_?.handleToolStart(this.toJSON(), typeof arg === "string" ? arg : JSON.stringify(arg), config.runId, void 0, void 0, void 0, config.runName);
delete config.runId;
let result;
try {
result = await this._call(parsed, runManager, config);
} catch (e) {
await runManager?.handleToolError(e);
throw e;
}
let content;
let artifact;
if (this.responseFormat === "content_and_artifact") if (Array.isArray(result) && result.length === 2) [content, artifact] = result;
else throw new Error(`Tool response format is "content_and_artifact" but the output was not a two-tuple.\nResult: ${JSON.stringify(result)}`);
else content = result;
let toolCallId;
if (_isToolCall(arg)) toolCallId = arg.id;
if (!toolCallId && _configHasToolCallId(config)) toolCallId = config.toolCall.id;
const formattedOutput = _formatToolOutput({
content,
artifact,
toolCallId,
name: this.name,
metadata: this.metadata
});
await runManager?.handleToolEnd(formattedOutput);
return formattedOutput;
}
};
/**
* Base class for Tools that accept input as a string.
*/
var Tool = class extends StructuredTool {
schema = z.object({ input: z.string().optional() }).transform((obj) => obj.input);
constructor(fields) {
super(fields);
}
/**
* @deprecated Use .invoke() instead. Will be removed in 0.3.0.
*
* Calls the tool with the provided argument and callbacks. It handles
* string inputs specifically.
* @param arg The input argument for the tool, which can be a string, undefined, or an input of the tool's schema.
* @param callbacks Optional callbacks for the tool.
* @returns A Promise that resolves with a string.
*/
call(arg, callbacks) {
const structuredArg = typeof arg === "string" || arg == null ? { input: arg } : arg;
return super.call(structuredArg, callbacks);
}
};
/**
* A tool that can be created dynamically from a function, name, and description.
*/
var DynamicTool = class extends Tool {
static lc_name() {
return "DynamicTool";
}
name;
description;
func;
constructor(fields) {
super(fields);
this.name = fields.name;
this.description = fields.description;
this.func = fields.func;
this.returnDirect = fields.returnDirect ?? this.returnDirect;
}
/**
* @deprecated Use .invoke() instead. Will be removed in 0.3.0.
*/
async call(arg, configArg) {
const config = parseCallbackConfigArg(configArg);
if (config.runName === void 0) config.runName = this.name;
return super.call(arg, config);
}
/** @ignore */
async _call(input, runManager, parentConfig) {
return this.func(input, runManager, parentConfig);
}
};
/**
* A tool that can be created dynamically from a function, name, and
* description, designed to work with structured data. It extends the
* StructuredTool class and overrides the _call method to execute the
* provided function when the tool is called.
*
* Schema can be passed as Zod or JSON schema. The tool will not validate
* input if JSON schema is passed.
*/
var DynamicStructuredTool = class extends StructuredTool {
static lc_name() {
return "DynamicStructuredTool";
}
name;
description;
func;
schema;
constructor(fields) {
super(fields);
this.name = fields.name;
this.description = fields.description;
this.func = fields.func;
this.returnDirect = fields.returnDirect ?? this.returnDirect;
this.schema = fields.schema;
}
/**
* @deprecated Use .invoke() instead. Will be removed in 0.3.0.
*/
async call(arg, configArg, tags) {
const config = parseCallbackConfigArg(configArg);
if (config.runName === void 0) config.runName = this.name;
return super.call(arg, config, tags);
}
_call(arg, runManager, parentConfig) {
return this.func(arg, runManager, parentConfig);
}
};
/**
* Abstract base class for toolkits in LangChain. Toolkits are collections
* of tools that agents can use. Subclasses must implement the `tools`
* property to provide the specific tools for the toolkit.
*/
var BaseToolkit = class {
getTools() {
return this.tools;
}
};
function tool(func, fields) {
const isSimpleStringSchema = isSimpleStringZodSchema(fields.schema);
const isStringJSONSchema = validatesOnlyStrings(fields.schema);
if (!fields.schema || isSimpleStringSchema || isStringJSONSchema) return new DynamicTool({
...fields,
description: fields.description ?? fields.schema?.description ?? `${fields.name} tool`,
func: async (input, runManager, config) => {
return new Promise((resolve, reject) => {
const childConfig = patchConfig(config, { callbacks: runManager?.getChild() });
AsyncLocalStorageProviderSingleton.runWithConfig(pickRunnableConfigKeys(childConfig), async () => {
try {
resolve(func(input, childConfig));
} catch (e) {
reject(e);
}
});
});
}
});
const schema = fields.schema;
const description = fields.description ?? fields.schema.description ?? `${fields.name} tool`;
return new DynamicStructuredTool({
...fields,
description,
schema,
func: async (input, runManager, config) => {
return new Promise((resolve, reject) => {
let listener;
const cleanup = () => {
if (config?.signal && listener) config.signal.removeEventListener("abort", listener);
};
if (config?.signal) {
listener = () => {
cleanup();
reject(getAbortSignalError(config.signal));
};
config.signal.addEventListener("abort", listener);
}
const childConfig = patchConfig(config, { callbacks: runManager?.getChild() });
AsyncLocalStorageProviderSingleton.runWithConfig(pickRunnableConfigKeys(childConfig), async () => {
try {
const result = await func(input, childConfig);
/**
* If the signal is aborted, we don't want to resolve the promise
* as the promise is already rejected.
*/
if (config?.signal?.aborted) {
cleanup();
return;
}
cleanup();
resolve(result);
} catch (e) {
cleanup();
reject(e);
}
});
});
}
});
}
function _formatToolOutput(params) {
const { content, artifact, toolCallId, metadata } = params;
if (toolCallId && !isDirectToolOutput(content)) if (typeof content === "string" || Array.isArray(content) && content.every((item) => typeof item === "object")) return new ToolMessage({
status: "success",
content,
artifact,
tool_call_id: toolCallId,
name: params.name,
metadata
});
else return new ToolMessage({
status: "success",
content: _stringify(content),
artifact,
tool_call_id: toolCallId,
name: params.name,
metadata
});
else return content;
}
function _stringify(content) {
try {
return JSON.stringify(content, null, 2) ?? "";
} catch (_noOp) {
return `${content}`;
}
}
//#endregion
export { BaseToolkit, DynamicStructuredTool, DynamicTool, StructuredTool, Tool, ToolInputParsingException, isLangChainTool, isRunnableToolLike, isStructuredTool, isStructuredToolParams, tool, tools_exports };
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