ai-utils.js/model-function/generate-text/TextDeltaEventSource.js

Build AI applications, chatbots, and agents with JavaScript and TypeScript.

import SecureJSON from "secure-json-parse";
import { z } from "zod";
import { AsyncQueue } from "./AsyncQueue.js";
import { parseEventSourceReadableStream } from "./parseEventSourceReadableStream.js";
const textEncoder = new TextEncoder();
const textDeltaEventDataSchema = z.object({
    textDelta: z.string().optional(),
    isFinished: z.boolean(),
});
function enqueueData(controller, data) {
    controller.enqueue(textEncoder.encode(`data: ${JSON.stringify(data)}\n\n`));
}
export function createTextDeltaEventSource(textDeltas) {
    return new ReadableStream({
        async start(controller) {
            for await (const textDelta of textDeltas) {
                enqueueData(controller, { textDelta, isFinished: false });
            }
            enqueueData(controller, { isFinished: true });
        },
    });
}
export function parseTextDeltaEventSource(stream, options) {
    const queue = new AsyncQueue();
    // run async (no await on purpose):
    parseEventSourceReadableStream({
        stream,
        callback: (event) => {
            if (event.type !== "event") {
                return;
            }
            try {
                const data = textDeltaEventDataSchema.parse(SecureJSON.parse(event.data));
                queue.push(data.textDelta);
                if (data.isFinished) {
                    queue.close();
                }
            }
            catch (error) {
                options?.errorHandler(error);
                queue.close();
            }
        },
    });
    return queue;
}