Differential D3243 Diff 16284 binaries/data/mods/public/gui/common/Observable.js

Changeset View

Standalone View

				/**
				* Observable is a self-proxy to enable opt-in reactive programming.
				* Properties of an Observable can be watched, and whenever they are changed
				* a callback will be fired.
				*/
				class Observable
				{
				constructor()
				{
				// Stores observers that are fired when the value is changed
				Object.defineProperty(this, "_changeObserver", {
				"value": {},
				"enumerable": false,
				});
				// Stores observers that are fired when the value is assigned to,
				// even if it isn't changed.
				Object.defineProperty(this, "_setObserver", {
				"value": {},
				"enumerable": false,
				});
				return new Proxy(this, {
				"set": (target, key, value) => {
				let old;
				if (Reflect.has(this, key))
				old = Reflect.get(this, key);
				Reflect.set(this, key, value);
				this._trigger(this._setObserver, key, old);
				if (old === undefined \|\| old !== value)
				this._trigger(this._changeObserver, key, old);
				return true;
				}
				});
				}

				_trigger(dict, key, old)
				{
				if (dict[key])
				for (let watcher of dict[key])
				watcher(key, old);
				}

				trigger(key, old)
				{
				this._trigger(this._setObserver, key, old);
				this._trigger(this._changeObserver, key, old);
				}

				watch(watcher, props, onlyChange = true)
				{
				let dic = onlyChange ? this._changeObserver : this._setObserver;
				for (let prop of props)
				{
				if (!dic[prop])
				dic[prop] = [];
				dic[prop].push(watcher);
				}
				}
				}