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chunk.ts
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chunk.ts
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import {
asyncEmpty,
empty,
isAsyncIterable,
isIterable,
} from "../_internal/utils";
import toArray from "../toArray";
import type IterableInfer from "../types/IterableInfer";
import type ReturnIterableIteratorType from "../types/ReturnIterableIteratorType";
import concurrent, { isConcurrent } from "./concurrent";
import take from "./take";
function* sync<T>(size: number, iterable: Iterable<T>): IterableIterator<T[]> {
const iterator = iterable[Symbol.iterator]();
while (true) {
const c = toArray(
take(size, {
[Symbol.iterator]() {
return iterator;
},
}),
);
if (c.length > 0) yield c;
if (c.length < size) return;
}
}
async function* asyncSequential<T>(
size: number,
iterable: AsyncIterable<T>,
): AsyncIterableIterator<T[]> {
let i = 0;
let items: T[] = [];
for await (const item of iterable) {
if (i++ < size) {
items.push(item);
}
if (i === size) {
yield items;
i = 0;
items = [];
}
}
if (items.length) {
yield items;
}
}
function async<T>(
size: number,
iterable: AsyncIterable<T>,
): AsyncIterableIterator<T[]> {
let _iterator: AsyncIterator<T[]>;
return {
async next(_concurrent: any) {
if (_iterator === undefined) {
_iterator = isConcurrent(_concurrent)
? asyncSequential(size, concurrent(_concurrent.length, iterable))
: asyncSequential(size, iterable);
}
return _iterator.next(_concurrent);
},
[Symbol.asyncIterator]() {
return this;
},
};
}
/**
* Returns Iterable/AsyncIterable of elements split into groups the length of size.
* If iterableIterator can't be split evenly, the final chunk will be the remaining elements.
*
* @example
* ```ts
* const iter = chunk(2, [1, 2, 3, 4]);
* iter.next() // {done:false, value:[1, 2]}
* iter.next() // {done:false, value:[3, 4]}
* iter.next() // {done:true, value: undefined}
*
* // with pipe
* pipe(
* [1, 2, 3, 4],
* chunk(2),
* toArray,
* ); // [[1, 2],[3, 4]]
*
* await pipe(
* Promise.resolve([1, 2, 3 ,4]),
* chunk(2),
* toArray,
* ); // [[1, 2],[3, 4]]
*
* // with toAsync
* await pipe(
* [Promise.resolve(1), Promise.resolve(2), Promise.resolve(3), Promise.resolve(4)],
* toAsync,
* chunk(2),
* toArray,
* ); // [[1, 2],[3, 4]]
* ```
*
* {@link https://codesandbox.io/s/fxts-chunk-gksly | Try It}
*
* see {@link https://fxts.dev/docs/pipe | pipe}, {@link https://fxts.dev/docs/toAsync | toAsync},
* {@link https://fxts.dev/docs/toArray | toArray}
*/
function chunk<T>(size: number, iterable: Iterable<T>): IterableIterator<T[]>;
function chunk<T>(
size: number,
iterable: AsyncIterable<T>,
): AsyncIterableIterator<T[]>;
function chunk<T extends Iterable<unknown> | AsyncIterable<unknown>>(
size: number,
): (iterable: T) => ReturnIterableIteratorType<T, IterableInfer<T>[]>;
function chunk<T extends Iterable<unknown> | AsyncIterable<unknown>>(
size: number,
iterable?: T,
):
| IterableIterator<IterableInfer<T>[]>
| AsyncIterableIterator<IterableInfer<T>[]>
| ((iterable: T) => ReturnIterableIteratorType<T, IterableInfer<T>[]>) {
if (iterable === undefined) {
return (iterable: T) =>
chunk(size, iterable as any) as ReturnIterableIteratorType<
T,
IterableInfer<T>[]
>;
}
if (isIterable(iterable)) {
if (size < 1) {
return empty();
} else {
return sync(size, iterable) as IterableIterator<IterableInfer<T>[]>;
}
}
if (isAsyncIterable(iterable)) {
if (size < 1) {
return asyncEmpty();
} else {
return async(size, iterable) as AsyncIterableIterator<IterableInfer<T>[]>;
}
}
throw new TypeError("'iterable' must be type of Iterable or AsyncIterable");
}
export default chunk;