45 lines
862 B
TypeScript
45 lines
862 B
TypeScript
export function unreachable(
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value: never,
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message = `No such case in exhaustive switch: ${value}`
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) {
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throw new Error(message)
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}
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export async function parallelForeach<T>(
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items: T[],
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task: (item: T) => Promise<void>,
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maxConcurrency: number
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): Promise<void> {
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const promises: Promise<void>[] = []
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let index = 0
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const processItem = async (item: T) => {
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try {
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await task(item)
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} finally {
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processNext()
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}
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}
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const processNext = () => {
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if (index >= items.length) {
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// No more items to process
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return
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}
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const item = items[index]
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index++
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const promise = processItem(item)
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promises.push(promise)
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if (promises.length >= maxConcurrency) {
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Promise.race(promises).then(processNext)
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} else {
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processNext()
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}
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}
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processNext()
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await Promise.all(promises)
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}
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