| 1 | // @flow strict-local
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| 2 |
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| 3 | import invariant from 'assert';
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| 4 |
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| 5 | export type Deferred<T> = {|
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| 6 | resolve(T): void,
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| 7 | reject(mixed): void,
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| 8 | |};
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| 9 |
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| 10 | export function makeDeferredWithPromise<T>(): {|
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| 11 | deferred: Deferred<T>,
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| 12 | promise: Promise<T>,
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| 13 | |} {
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| 14 | let deferred: ?Deferred<T>;
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| 15 | let promise = new Promise<T>((resolve, reject) => {
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| 16 | deferred = {resolve, reject};
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| 17 | });
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| 18 |
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| 19 | // Promise constructor callback executes synchronously, so this is defined
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| 20 | invariant(deferred != null);
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| 21 |
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| 22 | return {deferred, promise};
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| 23 | }
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