@pdftron/webviewer-react-toolkit/lib/data/memoizedPromise.js

A React component library for integrating with PDFTron WebViewer API.

import { futureableOrLazyToFuturable, memoizedPromiseToFuturableOrLazy } from './futurable';
/**
 * This class is responsible for wrapping tasks in a promise that won't be
 * executed until the result is actually required. Calling .get() on the class
 * will start the task, and resolve with the result. If the task has already
 * been executed once, it will resolve immediatly with the last result.
 */
export class MemoizedPromise {
    constructor(futurableOrLazy, options = {}) {
        /** Resolves with a promise for the value. */
        this.get = async () => {
            if (this._done)
                return this._result;
            this._result = futureableOrLazyToFuturable(this._futurableOrLazy);
            this._done = true;
            return this._result;
        };
        if (futurableOrLazy instanceof MemoizedPromise) {
            this._futurableOrLazy = memoizedPromiseToFuturableOrLazy(futurableOrLazy);
        }
        else {
            this._futurableOrLazy = futurableOrLazy;
        }
        this._result = undefined;
        this._done = false;
        if (options.preprocess || typeof this._futurableOrLazy !== 'function') {
            this._result = futureableOrLazyToFuturable(this._futurableOrLazy);
            this._done = true;
        }
    }
    /** Is true if the value is memoized. */
    get done() {
        return this._done;
    }
}