17 lines
471 B
TypeScript
17 lines
471 B
TypeScript
import { Transform, TransformOptions } from "stream";
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export function flatMap<T, R>(
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mapper:
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| ((chunk: T, encoding: string) => R[])
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| ((chunk: T, encoding: string) => Promise<R[]>),
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options?: TransformOptions,
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): Transform {
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return new Transform({
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...options,
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async transform(chunk: T, encoding, callback) {
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(await mapper(chunk, encoding)).forEach(c => this.push(c));
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callback();
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},
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});
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}
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