gnome-shell/js/misc/signalTracker.js

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/* exported TransientSignalHolder, connectObject, disconnectObject */
const { GObject } = imports.gi;
const destroyableTypes = [];
/**
* @private
* @param {Object} obj - an object
* @returns {bool} - true if obj has a 'destroy' GObject signal
*/
function _hasDestroySignal(obj) {
return destroyableTypes.some(type => obj instanceof type);
}
var TransientSignalHolder = GObject.registerClass(
class TransientSignalHolder extends GObject.Object {
static [GObject.signals] = {
'destroy': {},
};
constructor(owner) {
super();
if (_hasDestroySignal(owner))
owner.connectObject('destroy', () => this.destroy(), this);
}
destroy() {
this.emit('destroy');
}
});
registerDestroyableType(TransientSignalHolder);
class SignalManager {
/**
* @returns {SignalManager} - the SignalManager singleton
*/
static getDefault() {
if (!this._singleton)
this._singleton = new SignalManager();
return this._singleton;
}
constructor() {
this._signalTrackers = new Map();
}
/**
* @param {Object} obj - object to get signal tracker for
* @returns {SignalTracker} - the signal tracker for object
*/
getSignalTracker(obj) {
if (!this._signalTrackers.has(obj))
this._signalTrackers.set(obj, new SignalTracker(obj));
return this._signalTrackers.get(obj);
}
}
class SignalTracker {
/**
* @param {Object=} owner - object that owns the tracker
*/
constructor(owner) {
if (_hasDestroySignal(owner))
this._ownerDestroyId = owner.connect_after('destroy', () => this.clear());
this._owner = owner;
this._map = new Map();
}
/**
* @typedef SignalData
* @property {number[]} ownerSignals - a list of handler IDs
* @property {number} destroyId - destroy handler ID of tracked object
*/
/**
* @private
* @param {Object} obj - a tracked object
* @returns {SignalData} - signal data for object
*/
_getSignalData(obj) {
if (!this._map.has(obj))
this._map.set(obj, { ownerSignals: [], destroyId: 0 });
return this._map.get(obj);
}
/**
* @private
* @param {GObject.Object} obj - tracked widget
*/
_trackDestroy(obj) {
const signalData = this._getSignalData(obj);
if (signalData.destroyId)
return;
signalData.destroyId = obj.connect_after('destroy', () => this.untrack(obj));
}
_disconnectSignal(obj, id) {
const proto = obj instanceof GObject.Object
? GObject.Object.prototype
: Object.getPrototypeOf(obj);
proto['disconnect'].call(obj, id);
}
/**
* @param {Object} obj - tracked object
* @param {...number} handlerIds - tracked handler IDs
* @returns {void}
*/
track(obj, ...handlerIds) {
if (_hasDestroySignal(obj))
this._trackDestroy(obj);
this._getSignalData(obj).ownerSignals.push(...handlerIds);
}
/**
* @param {Object} obj - tracked object instance
* @returns {void}
*/
untrack(obj) {
const { ownerSignals, destroyId } = this._getSignalData(obj);
this._map.delete(obj);
ownerSignals.forEach(id => this._disconnectSignal(this._owner, id));
if (destroyId)
this._disconnectSignal(obj, destroyId);
}
/**
* @returns {void}
*/
clear() {
[...this._map.keys()].forEach(obj => this.untrack(obj));
}
/**
* @returns {void}
*/
destroy() {
this.clear();
if (this._ownerDestroyId)
this._disconnectSignal(this._owner, this._ownerDestroyId);
delete this._ownerDestroyId;
delete this._owner;
}
}
/**
* Connect one or more signals, and associate the handlers
* with a tracked object.
*
* All handlers for a particular object can be disconnected
* by calling disconnectObject(). If object is a {Clutter.widget},
* this is done automatically when the widget is destroyed.
*
* @param {object} thisObj - the emitter object
* @param {...any} args - a sequence of signal-name/handler pairs
* with an optional flags value, followed by an object to track
* @returns {void}
*/
function connectObject(thisObj, ...args) {
const getParams = argArray => {
const [signalName, handler, arg, ...rest] = argArray;
if (typeof arg !== 'number')
return [signalName, handler, 0, arg, ...rest];
const flags = arg;
if (flags > GObject.ConnectFlags.SWAPPED)
throw new Error(`Invalid flag value ${flags}`);
if (flags === GObject.ConnectFlags.SWAPPED)
throw new Error('Swapped signals are not supported');
return [signalName, handler, flags, ...rest];
};
const connectSignal = (emitter, signalName, handler, flags) => {
const isGObject = emitter instanceof GObject.Object;
const func = flags === GObject.ConnectFlags.AFTER && isGObject
? 'connect_after'
: 'connect';
const emitterProto = isGObject
? GObject.Object.prototype
: Object.getPrototypeOf(emitter);
return emitterProto[func].call(emitter, signalName, handler);
};
const signalIds = [];
while (args.length > 1) {
const [signalName, handler, flags, ...rest] = getParams(args);
signalIds.push(connectSignal(thisObj, signalName, handler, flags));
args = rest;
}
let [obj] = args;
if (!obj)
obj = globalThis;
const tracker = SignalManager.getDefault().getSignalTracker(thisObj);
tracker.track(obj, ...signalIds);
}
/**
* Disconnect all signals that were connected for
* the specified tracked object
*
* @param {Object} thisObj - the emitter object
* @param {Object} obj - the tracked object
* @returns {void}
*/
function disconnectObject(thisObj, obj) {
SignalManager.getDefault().getSignalTracker(thisObj).untrack(obj);
}
/**
* Register a GObject type as having a 'destroy' signal
* that should disconnect all handlers
*
* @param {GObject.Type} gtype - a GObject type
*/
function registerDestroyableType(gtype) {
if (!GObject.type_is_a(gtype, GObject.Object))
throw new Error(`${gtype} is not a GObject subclass`);
if (!GObject.signal_lookup('destroy', gtype))
throw new Error(`${gtype} does not have a destroy signal`);
destroyableTypes.push(gtype);
}