55 lines
1.3 KiB
TypeScript
55 lines
1.3 KiB
TypeScript
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export function* chunks<T>(iter: Iterable<T>, size = 100): Iterable<T[]> {
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let buf: T[] = []
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for (const item of iter) {
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buf.push(item)
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if (buf.length === size) {
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yield buf
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buf = []
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}
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}
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if (buf.length) yield buf
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}
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export function zip<T1, T2>(
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iter1: Iterable<T1>,
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iter2: Iterable<T2>
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): Iterable<[T1, T2]>
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export function zip<T1, T2, T3>(
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iter1: Iterable<T1>,
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iter2: Iterable<T2>,
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iter3: Iterable<T3>
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): Iterable<[T1, T2, T3]>
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export function zip(...iters: Iterable<any>[]): Iterable<any[]>
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export function* zip(...iters: Iterable<any>[]): Iterable<any[]> {
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const iterables = iters.map((iter) => iter[Symbol.iterator]())
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for (;;) {
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const row = []
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for (const iter of iterables) {
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const res = iter.next()
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if (res.done) return
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row.push(res.value)
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}
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yield row
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}
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}
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export async function groupByAsync<T, K extends string | number>(
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items: Iterable<T>,
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keyer: (item: T) => Promise<K>
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): Promise<Record<K, T[]>> {
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const ret: Record<K, T[]> = {} as any
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for (const item of items) {
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const key = await keyer(item)
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if (!ret[key]) ret[key] = []
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ret[key].push(item)
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}
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return ret
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}
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