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PrivateProperty

Weakly references a value to a specified object. May be used to create private fields.

Version vom 27.10.2019. Aktuellste Version

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greasyfork.org/scripts/391608/744459/PrivateProperty.js 

// ==UserScript==
// @name         PrivateProperty
// @namespace    hoehleg.userscripts.private
// @version      0.1
// @description  Weakly references a value to a specified object. May be used to create private fields.
// @author       Gerrit Höhle
// @grant        none
// ==/UserScript==

/* jshint esversion: 6 */
const PrivateProperty = (() => {

    const getOrCreate = (privateProperty, keyObj, { initialValue = privateProperty._initialValue, value } = {}) => {
        let data = privateProperty._weakReferences.get(keyObj);
        if (!data) {
            data = { initialValue: initialValue, value: value };
            privateProperty._weakReferences.set(keyObj, data);
        }
        return data;
    };

    return class PrivateProperty {

        constructor(initialValue) {
            this._weakReferences = new WeakMap();
            this._initialValue = initialValue;
        }

        init(object, initialValueSpecific = this._initialValue) {
            const value = (typeof initialValueSpecific === "function") ? initialValueSpecific() : initialValueSpecific;
            this._weakReferences.delete(object);
            this._weakReferences.set(object, { initialValue: initialValueSpecific, value: value });
            return this;
        }

        has(object) {
            return this._weakReferences.has(object);
        }

        get(object) {
            const data = this._weakReferences.get(object);
            if (data) {
                return data.value;
            }
        }

        set(object, value) {
            const data = getOrCreate(this, object);
            data.value = value;
        }

        getInitialValue(object) {
            const data = this._weakReferences.get(object);
            return data ? data.initialValue : this._initialValue;
        }

        getOrCompute(object, fnc) {
            let data = this._weakReferences.get(object);
            if (!data) {
                data = { initialValue: this._initialValue, value: fnc() };
                this._weakReferences.set(data);
            }
            return data.value;
        }

        for(object) {
            return {
                init: PrivateProperty.prototype.init.bind(this, object),
                hasValue: PrivateProperty.prototype.hasValue.bind(this, object),
                get: PrivateProperty.prototype.get.bind(this, object),
                set: PrivateProperty.prototype.set.bind(this, object),
                getInitialValue: PrivateProperty.prototype.getInitialValue.bind(this, object),
                getOrCompute: PrivateProperty.prototype.getOrCompute.bind(this, object),
                valueOf: PrivateProperty.prototype.get.bind(this, object),
                toString: () => (String(PrivateProperty.prototype.get.bind(this, object)))
            };
        }
    };
})();