heli-agri/dist/functions.js

HeliAgri is a high-performance, feature-packed library for creating interactive maps on the web. It can display map tiles, vector data and markers loaded from any source on any web page. OpenLayers has been developed to further the use of geographic infor

/**
 * @module ol/functions
 */
import { equals as arrayEquals } from './array.js';
/**
 * Always returns true.
 * @return {boolean} true.
 */
export function TRUE() {
    return true;
}
/**
 * Always returns false.
 * @return {boolean} false.
 */
export function FALSE() {
    return false;
}
/**
 * A reusable function, used e.g. as a default for callbacks.
 *
 * @return {void} Nothing.
 */
export function VOID() { }
/**
 * Wrap a function in another function that remembers the last return.  If the
 * returned function is called twice in a row with the same arguments and the same
 * this object, it will return the value from the first call in the second call.
 *
 * @param {function(...any): ReturnType} fn The function to memoize.
 * @return {function(...any): ReturnType} The memoized function.
 * @template ReturnType
 */
export function memoizeOne(fn) {
    let called = false;
    /** @type {ReturnType} */
    let lastResult;
    /** @type {Array<any>} */
    let lastArgs;
    let lastThis;
    return function () {
        const nextArgs = Array.prototype.slice.call(arguments);
        if (!called || this !== lastThis || !arrayEquals(nextArgs, lastArgs)) {
            called = true;
            lastThis = this;
            lastArgs = nextArgs;
            lastResult = fn.apply(this, arguments);
        }
        return lastResult;
    };
}
/**
 * @template T
 * @param {function(): (T | Promise<T>)} getter A function that returns a value or a promise for a value.
 * @return {Promise<T>} A promise for the value.
 */
export function toPromise(getter) {
    function promiseGetter() {
        let value;
        try {
            value = getter();
        }
        catch (err) {
            return Promise.reject(err);
        }
        if (value instanceof Promise) {
            return value;
        }
        return Promise.resolve(value);
    }
    return promiseGetter();
}