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var chromium = chromium || {};
(function () {
native function AttachEvent(eventName);
native function DetachEvent(eventName);
// Event object. If opt_eventName is provided, this object represents
// the unique instance of that named event, and dispatching an event
// with that name will route through this object's listeners.
//
// Example:
// chromium.ontabchanged = new Event('tabchanged');
// chromium.ontabchanged.addListener(function(data) { alert(data); });
// chromium.Event.dispatch_('tabchanged', 'hi');
// will result in an alert dialog that says 'hi'.
chromium.Event = function(opt_eventName) {
this.eventName_ = opt_eventName;
this.listeners_ = [];
};
// A map of event names to the event object that is registered to that name.
chromium.Event.attached_ = {};
// Dispatches a named event with the given JSON data, which is deserialized
// before dispatch.
chromium.Event.dispatchJSON_ = function(name, data) {
if (chromium.Event.attached_[name]) {
if (data) {
data = goog.json.parse(data);
}
chromium.Event.attached_[name].dispatch(data);
}
};
// Dispatches a named event with the given object data.
chromium.Event.dispatch_ = function(name, data) {
if (chromium.Event.attached_[name]) {
chromium.Event.attached_[name].dispatch(data);
}
};
// Registers a callback to be called when this event is dispatched.
chromium.Event.prototype.addListener = function(cb) {
this.listeners_.push(cb);
if (this.listeners_.length == 1) {
this.attach_();
}
};
// Unregisters a callback.
chromium.Event.prototype.removeListener = function(cb) {
var idx = this.findListener_(cb);
if (idx == -1) {
return;
}
this.listeners_.splice(idx, 1);
if (this.listeners_.length == 0) {
this.detach_();
}
};
// Test if the given callback is registered for this event.
chromium.Event.prototype.hasListener = function(cb) {
return this.findListeners_(cb) > -1;
};
// Returns the index of the given callback if registered, or -1 if not
// found.
chromium.Event.prototype.findListener_ = function(cb) {
for (var i = 0; i < this.listeners_.length; i++) {
if (this.listeners_[i] == cb) {
return i;
}
}
return -1;
};
// Dispatches this event object to all listeners, passing all supplied
// arguments to this function each listener.
chromium.Event.prototype.dispatch = function(varargs) {
var args = Array.prototype.slice.call(arguments);
for (var i = 0; i < this.listeners_.length; i++) {
try {
this.listeners_[i].apply(null, args);
} catch (e) {
console.error(e);
}
}
};
// Attaches this event object to its name. Only one object can have a given
// name.
chromium.Event.prototype.attach_ = function() {
AttachEvent(this.eventName_);
if (!this.eventName_)
return;
if (chromium.Event.attached_[this.eventName_]) {
throw new Error("chromium.Event '" + this.eventName_ +
"' is already attached.");
}
chromium.Event.attached_[this.eventName_] = this;
};
// Detaches this event object from its name.
chromium.Event.prototype.detach_ = function() {
DetachEvent(this.eventName_);
if (!this.eventName_)
return;
if (!chromium.Event.attached_[this.eventName_]) {
throw new Error("chromium.Event '" + this.eventName_ +
"' is not attached.");
}
delete chromium.Event.attached_[this.eventName_];
};
})();
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