@helia/verified-fetch/dist/src/utils/get-stream-from-async-iterable.js

A fetch-like API for obtaining verified & trustless IPFS content on the web

import { AbortError } from '@libp2p/interface';
import { CustomProgressEvent } from 'progress-events';
import { NoContentError } from '../errors.js';
/**
 * Converts an async iterator of Uint8Array bytes to a stream and returns the first chunk of bytes
 */
export async function getStreamFromAsyncIterable(iterator, path, logger, options) {
    const log = logger.forComponent('helia:verified-fetch:get-stream-from-async-iterable');
    const reader = iterator[Symbol.asyncIterator]();
    const { value: firstChunk, done } = await reader.next();
    if (done === true) {
        log.error('no content found for path', path);
        throw new NoContentError();
    }
    const stream = new ReadableStream({
        async start(controller) {
            // the initial value is already available
            options?.onProgress?.(new CustomProgressEvent('verified-fetch:request:progress:chunk'));
            controller.enqueue(firstChunk);
        },
        async pull(controller) {
            const { value, done } = await reader.next();
            if (options?.signal?.aborted) {
                controller.error(new AbortError(options.signal.reason ?? 'signal aborted by user'));
                controller.close();
                return;
            }
            if (done === true) {
                if (value != null) {
                    options?.onProgress?.(new CustomProgressEvent('verified-fetch:request:progress:chunk'));
                    controller.enqueue(value);
                }
                controller.close();
                return;
            }
            options?.onProgress?.(new CustomProgressEvent('verified-fetch:request:progress:chunk'));
            controller.enqueue(value);
        }
    });
    return {
        stream,
        firstChunk
    };
}
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