@johngw/stream/dist/transformers/flat.js

Reactive programming tools using the WHATWG Streams API.

import { isArrayLike, isAsyncIterable, isIterable, } from '@johngw/stream-common/Object';
/**
 * Deeply flattens `Iterable`s, `AsyncIterable`s & `ArrayLike`s.
 *
 * @group Transformers
 * @example
 * ```
 * --[1]--2----[3,[4]]---|
 *
 * flat()
 *
 * --1----2-----3-4------|
 * ```
 */
export function flat() {
    return new TransformStream(new FlatTransformer());
}
class FlatTransformer {
    transform(chunk, controller) {
        return typeof chunk === 'string'
            ? controller.enqueue(chunk)
            : isIterable(chunk)
                ? this.#transformIterator(chunk, controller)
                : isAsyncIterable(chunk)
                    ? this.#transformAsyncIterator(chunk, controller)
                    : isArrayLike(chunk)
                        ? this.#transformArrayLike(chunk, controller)
                        : controller.enqueue(chunk);
    }
    async #transformIterator(chunk, controller) {
        for (const x of chunk)
            await this.transform(x, controller);
    }
    async #transformAsyncIterator(chunk, controller) {
        for await (const x of chunk)
            await this.transform(x, controller);
    }
    async #transformArrayLike(chunk, controller) {
        for (let i = 0; i < chunk.length; i++)
            await this.transform(chunk[i], controller);
    }
}
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