cylon/lib/basestar.js

126 lines
3.7 KiB
JavaScript

"use strict";
var EventEmitter = require("events").EventEmitter;
var Utils = require("./utils"),
_ = require("./utils/helpers");
/**
* The Basestar class is a wrapper class around EventEmitter that underpins most
* other Cylon adaptor/driver classes, providing useful external base methods
* and functionality.
*
* @constructor Basestar
*/
var Basestar = module.exports = function Basestar() {
Utils.classCallCheck(this, Basestar);
};
Utils.subclass(Basestar, EventEmitter);
/**
* Proxies calls from all methods in the source to a target object
*
* @param {String[]} methods methods to proxy
* @param {Object} target object to proxy methods to
* @param {Object} source object to proxy methods from
* @param {Boolean} [force=false] whether or not to overwrite existing methods
* @return {Object} the source
*/
Basestar.prototype.proxyMethods = Utils.proxyFunctionsToObject;
// Public: Triggers a callback and emits an event with provided data
//
// event - name of event to be triggered
// callback - callback function to be triggered
// ...data - additional arguments to be passed to both event/callback
//
// Returns nothing
/**
* Triggers the provided callback, and emits an event with the provided data.
*
* If an error is provided, emits the 'error' event.
*
* @param {String} event what event to emit
* @param {Function} callback function to be invoked with error/data
* @param {*} err possible error value
* @param {...*} data data values to be passed to error/callback
* @return {void}
*/
Basestar.prototype.respond = function(event, callback, err) {
var args = Array.prototype.slice.call(arguments, 3);
if (err) {
this.emit("error", err);
} else {
this.emit.apply(this, [event].concat(args));
}
if (typeof callback === "function") {
callback.apply(this, [err].concat(args));
}
};
/**
* Defines an event handler to proxy events from a source object to a target
*
* @param {Object} opts event options
* @param {EventEmitter} opts.source source of events to listen for
* @param {EventEmitter} opts.target target new events should be emitted from
* @param {String} opts.eventName name of event to listen for, and proxy
* @param {Bool} [opts.sendUpdate=false] whether to emit the 'update' event
* @param {String} [opts.targetEventName] new event name to emit from target
* @return {EventEmitter} the source object
*/
Basestar.prototype.defineEvent = function(opts) {
opts.sendUpdate = opts.sendUpdate || false;
opts.targetEventName = opts.targetEventName || opts.eventName;
opts.source.on(opts.eventName, function() {
var args = arguments.length >= 1 ? [].slice.call(arguments, 0) : [];
args.unshift(opts.targetEventName);
opts.target.emit.apply(opts.target, args);
if (opts.sendUpdate) {
args.unshift("update");
opts.target.emit.apply(opts.target, args);
}
});
return opts.source;
};
/**
* A #defineEvent shorthand for adaptors.
*
* Proxies events from an adaptor's connector to the adaptor itself.
*
* @param {Object} opts proxy options
* @return {EventEmitter} the adaptor's connector
*/
Basestar.prototype.defineAdaptorEvent = function(opts) {
return this._proxyEvents(opts, this.connector, this);
};
/**
* A #defineEvent shorthand for drivers.
*
* Proxies events from an driver's connection to the driver itself.
*
* @param {Object} opts proxy options
* @return {EventEmitter} the driver's connection
*/
Basestar.prototype.defineDriverEvent = function(opts) {
return this._proxyEvents(opts, this.connection, this);
};
Basestar.prototype._proxyEvents = function(opts, source, target) {
opts = _.isString(opts) ? { eventName: opts } : opts;
opts.source = source;
opts.target = target;
return this.defineEvent(opts);
};