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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 | 8x 8x 8x 8x 8x 1194x 792x 792x 792x 402x 5x 5x 397x 397x 396x 395x 396x 2x 2x 394x 394x 394x | import { Readable } from 'node:stream'
import type { PaginationList, PaginationListWithCount } from './apiTypes.ts'
type FetchPage<T> = (
pageno: number,
) =>
| PaginationList<T>
| PromiseLike<PaginationList<T>>
| PaginationListWithCount<T>
| PromiseLike<PaginationListWithCount<T>>
export default class PaginationStream<T> extends Readable {
private _fetchPage: FetchPage<T>
private _nitems?: number
private _pageno = 0
private _items: T[] = []
private _itemsRead = 0
constructor(fetchPage: FetchPage<T>) {
super({ objectMode: true })
this._fetchPage = fetchPage
}
override async _read() {
if (this._items.length > 0) {
this._itemsRead++
process.nextTick(() => this.push(this._items.pop()))
return
}
if (this._nitems != null && this._itemsRead >= this._nitems) {
process.nextTick(() => this.push(null))
return
}
try {
const { items, ...rest } = await this._fetchPage(++this._pageno)
if ('count' in rest) {
this._nitems = rest.count
}
// Some endpoints can return a non-zero `count` even when the current query/page yields no
// items (e.g. filtering by date range). An empty page is a reliable signal that we are done.
if (items.length === 0) {
process.nextTick(() => this.push(null))
return
}
this._items = Array.from(items)
this._items.reverse()
this._read()
} catch (err) {
this.emit('error', err)
}
}
}
|