custom-event-emitter.js
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var util = require("util")
, EventEmitter = require("events").EventEmitter
, Promise = require("bluebird")
, proxyEventKeys = ['success', 'error', 'sql']
, Utils = require('../utils')
var bindToProcess = function(fct) {
if (fct && process.domain) {
return process.domain.bind(fct)
}
return fct
};
module.exports = (function() {
var CustomEventEmitter = function(fct) {
this.fct = bindToProcess(fct)
}
util.inherits(CustomEventEmitter, EventEmitter)
CustomEventEmitter.prototype.run = function() {
Utils.tick(function() {
if (this.fct) {
this.fct.call(this, this)
}
}.bind(this))
return this
}
CustomEventEmitter.prototype.emit = function(type) {
this._events = this._events || {};
// Override default 'error' event logic
if (type === 'error' && !this._events.error) {
// No error listener
var er = arguments[1];
// If error argument is an object but no error,
// boil it down to the value of the first key
// (probably an Array in most cases)
if (Utils._.isObject(er) && !(er instanceof Error)) {
er = er[Object.keys(er)[0]]
}
// If error argument is an array, make sure we
// pass only the first error to the original
// .emit() function of EventEmitter
if (er instanceof Array) {
er = Utils._.flatten(er)[0]
}
// We don't want to throw strings. Make them Errors!
if (typeof er === "string") {
er = new Error(er)
}
arguments[1] = er
}
EventEmitter.prototype.emit.apply(this, arguments);
};
/**
Shortcut methods (success, ok) for listening for success events.
Params:
- fct: A function that gets executed once the *success* event was triggered.
Result:
The function returns the instance of the query.
*/
CustomEventEmitter.prototype.success =
CustomEventEmitter.prototype.ok =
function(fct) {
this.on('success', bindToProcess(fct))
return this
}
/**
Shortcut methods (failure, fail, error) for listening for error events.
Params:
- fct: A function that gets executed once the *error* event was triggered.
Result:
The function returns the instance of the query.
*/
CustomEventEmitter.prototype.failure =
CustomEventEmitter.prototype.fail =
CustomEventEmitter.prototype.error =
function(fct) {
this.on('error', bindToProcess(fct))
return this;
}
CustomEventEmitter.prototype.done =
CustomEventEmitter.prototype.complete =
function(fct) {
fct = bindToProcess(fct);
this.on('error', function(err) { fct(err, null) })
.on('success', function() {
var args = Array.prototype.slice.call(arguments);
args.unshift(null);
fct.apply(fct, args);
})
return this
}
CustomEventEmitter.prototype.sql = function(fct) {
this.on('sql', bindToProcess(fct))
return this;
}
/**
* Proxy every event of this custom event emitter to another one.
*
* @param {CustomEventEmitter} emitter The event emitter that should receive the events.
* @return {void}
*/
CustomEventEmitter.prototype.proxy = function(emitter, options) {
options = Utils._.extend({
events: proxyEventKeys,
skipEvents: []
}, options || {})
options.events = Utils._.difference(options.events, options.skipEvents)
options.events.forEach(function (eventKey) {
this.on(eventKey, function (result) {
emitter.emit(eventKey, result)
})
}.bind(this))
return this
}
CustomEventEmitter.prototype.then = function(onFulfilled, onRejected) {
var self = this
onFulfilled = bindToProcess(onFulfilled)
onRejected = bindToProcess(onRejected)
return new Promise(function (resolve, reject) {
self.on('error', reject)
.on('success', resolve)
}).then(onFulfilled, onRejected)
}
CustomEventEmitter.prototype.spread = function(onFulfilled, onRejected) {
var self = this
onFulfilled = bindToProcess(onFulfilled)
onRejected = bindToProcess(onRejected)
return new Promise(function (resolve, reject) {
self.on('error', reject)
.on('success', function () {
resolve(Array.prototype.slice.apply(arguments)) // Transform args to an array
})
}).spread(onFulfilled, onRejected)
}
return CustomEventEmitter
})()