Jon Staab
36 lines
998 B
TypeScript
36 lines
998 B
TypeScript
/** Promise type with strongly typed error */
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export type CustomPromise<T, E> = Promise<T> & {
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__errorType: E
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}
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/**
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* Creates a Promise with strongly typed error
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* @param executor - Promise executor function
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* @returns Promise with typed error
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*/
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export function makePromise<T, E>(
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executor: (resolve: (value: T | PromiseLike<T>) => void, reject: (reason: E) => void) => void,
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): CustomPromise<T, E> {
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return new Promise(executor) as CustomPromise<T, E>
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}
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/** Promise with exposed resolve/reject functions and typed error */
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export type Deferred<T, E = T> = CustomPromise<T, E> & {
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resolve: (arg: T) => void
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reject: (arg: E) => void
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}
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/**
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* Creates a Deferred promise
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* @returns Promise with resolve/reject methods exposed
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*/
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export const defer = <T, E = T>(): Deferred<T, E> => {
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let resolve, reject
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const p = makePromise((resolve_, reject_) => {
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resolve = resolve_
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reject = reject_
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})
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return Object.assign(p, {resolve, reject}) as unknown as Deferred<T, E>
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}
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