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async-buffer.js
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async-buffer.js
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import { curry } from '../../internal/curry.js';
import { asyncCallReturn } from '../../internal/async-iterable.js';
import { AsyncIterableIterator } from '../../internal/async-iterable-iterator.js';
import { CircularBuffer } from '../../internal/circular-buffer.js';
import { isPositiveInteger } from '../../internal/number.js';
import { isAsyncIterable } from '../is-async-iterable/is-async-iterable.js';
import { isIterable } from '../../internal/iterable.js';
async function* empty() {}
function getIterator(iterable) {
if (iterable == null) {
return empty();
} else if (isAsyncIterable(iterable)) {
return iterable[Symbol.asyncIterator]();
} else if (isIterable(iterable)) {
return iterable[Symbol.iterator]();
} else {
throw new Error(`asyncBuffer expected an iterable but received ${iterable}.`);
}
}
export class Bufferator extends AsyncIterableIterator {
constructor(iterable, concurrency) {
super();
this.iterator = getIterator(iterable);
this.buffer = new CircularBuffer(concurrency);
while (!this.buffer.isFull()) {
this.buffer.push(Promise.resolve(this.iterator.next()));
}
}
async next() {
const { buffer, iterator } = this;
return await buffer.push(Promise.resolve(iterator.next()));
}
async return() {
return await asyncCallReturn(this.iterator);
}
}
export function __asyncBuffer(source, n) {
return new Bufferator(source, n);
}
export const asyncBuffer = /*#__PURE__*/ curry(function asyncBuffer(n, source) {
if (n === undefined) return;
if (n !== Infinity && !isPositiveInteger(n)) {
throw new Error('Concurrency must be an integer > 0');
} else if (n > 1024) {
/**
* When concurrency is n, this code will always make at least n promises.
* n - 1 of those promises will always be created after the promise that
* will eventually resolve with { done: true }. Therefore concurrency must
* have limits, and it will usually be sensible to keep it in the 2 - 32 range.
*/
throw new Error('Concurrency argument to asyncBuffer must be <= 1024');
}
return __asyncBuffer(source, n);
});