Weakly references a value to a specified object. May be used to create private fields.
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greasyfork.org/scripts/391608/744693/PrivateProperty.js
// ==UserScript==
// @name PrivateProperty
// @namespace hoehleg.userscripts.private
// @version 0.2
// @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 = (() => {
let prototypeFunctions;
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 = this._weakReferences.get(object) || {
initialValue: this._initialValue
};
data.value = value;
this._weakReferences.set(object, data);
}
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(object, data);
}
return data.value;
}
for(object) {
const bound = prototypeFunctions.map(([propName, fnc]) => ({ [propName]: fnc.bind(this, object) }));
return Object.assign({}, ...bound);
}
}
prototypeFunctions = Object.getOwnPropertyNames(PrivateProperty.prototype)
.filter(propName => typeof PrivateProperty.prototype[propName] === "function")
.filter(propName => propName !== "constructor")
.filter(propName => propName !== "for")
.map(propName => ([ [propName], PrivateProperty.prototype[propName] ]));
return PrivateProperty;
})();