@loaders.gl/loader-utils/dist/lib/iterators/async-iteration.js

Framework-independent loaders for 3D graphics formats

import { concatenateArrayBuffers } from "../binary-utils/array-buffer-utils.js";
// GENERAL UTILITIES
/**
 * Iterate over async iterator, without resetting iterator if end is not reached
 * - forEach intentionally does not reset iterator if exiting loop prematurely
 *   so that iteration can continue in a second loop
 * - It is recommended to use a standard for-await as last loop to ensure
 *   iterator gets properly reset
 *
 * TODO - optimize using sync iteration if argument is an Iterable?
 *
 * @param iterator
 * @param visitor
 */
export async function forEach(iterator, visitor) {
    // eslint-disable-next-line
    while (true) {
        const { done, value } = await iterator.next();
        if (done) {
            iterator.return();
            return;
        }
        const cancel = visitor(value);
        if (cancel) {
            return;
        }
    }
}
// Breaking big data into iterable chunks, concatenating iterable chunks into big data objects
/**
 * Concatenates all data chunks yielded by an (async) iterator
 * This function can e.g. be used to enable atomic parsers to work on (async) iterator inputs
 */
export async function concatenateArrayBuffersAsync(asyncIterator) {
    const arrayBuffers = [];
    for await (const chunk of asyncIterator) {
        arrayBuffers.push(chunk);
    }
    return concatenateArrayBuffers(...arrayBuffers);
}
export async function concatenateStringsAsync(asyncIterator) {
    const strings = [];
    for await (const chunk of asyncIterator) {
        strings.push(chunk);
    }
    return strings.join('');
}