it-split/dist/src/index.js

Splits Uint8Arrays emitted by an (async) iterable by a delimiter

/**
 * @packageDocumentation
 *
 * Searches `Uint8Array`s emitted by an (async)iterable for a delimiter and yields chunks split by that delimiter.
 *
 * @example
 *
 * ```javascript
 * import split from 'it-split'
 *
 * const encoder = new TextEncoder()
 *
 * // This can also be an iterator, generator, etc
 * const values = [
 *   encoder.encode('hello\nwor'),
 *   encoder.encode('ld')
 * ]
 *
 * const arr = all(split(values))
 *
 * console.info(arr) // [encoder.encode('hello'), encoder.encode('world')]
 * ```
 *
 * You can also split by arbitrary delimiters:
 *
 * ```javascript
 * const values = [
 *   Uint8Array.from([0, 1, 2, 3]),
 *   Uint8Array.from([0, 1, 2, 3]),
 *   Uint8Array.from([1, 1, 2])
 * ]
 * const delimiter = Uint8Array.from([1, 2])
 *
 * const arr = all(split(values, {
 *   delimiter
 * }))
 *
 * console.info(arr) // [ Buffer.from([0]), Buffer.from([3, 0]), Buffer.from([3, 1]) ]
 * ```
 *
 * Async sources must be awaited:
 *
 * ```javascript
 * import split from 'it-split'
 *
 * const encoder = new TextEncoder()
 *
 * const values = async function * () {
 *   yield * [
 *     encoder.encode('hello\nwor'),
 *     encoder.encode('ld')
 *   ]
 * }
 *
 * const arr = await all(split(values()))
 *
 * console.info(arr) // [encoder.encode('hello'), encoder.encode('world')]
 * ```
 */
import { Uint8ArrayList } from 'uint8arraylist';
function isAsyncIterable(thing) {
    return thing[Symbol.asyncIterator] != null;
}
function split(source, options = {}) {
    const bl = new Uint8ArrayList();
    const delimiter = options.delimiter ?? new TextEncoder().encode('\n');
    if (isAsyncIterable(source)) {
        return (async function* () {
            for await (const buf of source) {
                bl.append(buf);
                yield* yieldUntilEnd(bl, delimiter);
            }
            yield* yieldUntilEnd(bl, delimiter);
            if (bl.length > 0) {
                yield bl.slice();
            }
        })();
    }
    return (function* () {
        for (const buf of source) {
            bl.append(buf);
            yield* yieldUntilEnd(bl, delimiter);
        }
        yield* yieldUntilEnd(bl, delimiter);
        if (bl.length > 0) {
            yield bl.slice();
        }
    })();
}
function* yieldUntilEnd(bl, delimiter) {
    let index = bl.indexOf(delimiter);
    while (index !== -1) {
        yield bl.slice(0, index);
        bl.consume(index + delimiter.length);
        index = bl.indexOf(delimiter);
    }
}
export default split;
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