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7
.editorconfig
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7
.editorconfig
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root = true
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[**]
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indent_style = tab
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tab_width = 4
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charset = utf-8
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end_of_line = lf
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2
LICENSE
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2
LICENSE
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Copyright (c) 2014, Alex A. Naanou
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Copyright (c) 2014-2023, Alex A. Naanou
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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100
README.md
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100
README.md
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guaranteeEvents
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===============
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This module exports a single function that when passed an event(s) and an
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[EventEmitter](http://nodejs.org/api/events.html#events_class_events_eventemitter)
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compatible object will register a couple of handlers that
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will provide the following functionality:
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* Cache event data for each event of the given type that gets emitted.
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* Call new handlers of the specified event with each of the prior event
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data sets in order of event occurrence.
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* Add a `.clearGuaranteedQueue(<event>)` method to the emitter to facilitate
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event cache cleaning.
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This is useful for modules like [glob](https://github.com/isaacs/node-glob)
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that use the [EventEmitter](http://nodejs.org/api/events.html#events_class_events_eventemitter)
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model to pass data to the user (see examples below).
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This is similar to how state change handlers work in
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[jQuery.Deferred](http://api.jquery.com/category/deferred-object/) or in
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[Promise](https://promisesaplus.com/) objects.
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Install
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-------
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```
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$ npm install guarantee-events
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```
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Basic Examples
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-------------
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A synthetic example illustrating the basic functionality:
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```javascript
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var emitter = new (require('events').EventEmitter)
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var guaranteeEvents = require('guarantee-events')
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guaranteeEvents('event', emitter)
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// emit some events...
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emitter.emit('event', 'some data')
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emitter.emit('event', 'some', 'more', 'data')
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// Here the handler will be called for each event it missed...
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emitter.on('event', function(){ console.log([].slice.apply(argumnts).join(' ')) })
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emitter.emit('event', 'some data')
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```
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A real-life use-case using the excellent [glob](https://github.com/isaacs/node-glob)
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utility:
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```javascript
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var glob = require('glob')
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var guaranteeEvents = require('guarantee-events')
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// build a glob object with cached 'match' and 'end' events...
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var results = guaranteeEvents('match end', glob('**/*js'))
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// Do stuff for some time...
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// This will not miss a single result, regardless of how long it
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// took to do stuff...
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results.on('match', function(path){ console.log('found: '+path) })
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```
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Cache cleaning and use for long running emitters
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------------------------------------------------
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One of the dangers in using this in long running event emitters is _cache
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buildup_ -- the data for each event emitted will get stored and this
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might get quite large, this, if not managed, is a potential memory leak.
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To deal with this issue a `.clearGuaranteedQueue(<event>)` method is
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added to the emitter, this will clear the cache for a specific event.
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This and has a shorthand form `.clearGuaranteedQueue('*')` that will
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clear the cache for all wrapped events.
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So for the above example:
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```javascript
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// This this will drop all the prior match data, so newly registred handlers
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// will not see them...
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// NOTE: this will not affect the underlaying glob object in any way.
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results.clearGuaranteedQueue('match')
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```
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59
index.js
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59
index.js
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*
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**********************************************************************/
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// Clear event cache...
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//
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// This is added as a method to the emitter passed to guaranteeEvents(..)...
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//
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// NOTE: his has the same event names semantics as guaranteeEvents(..)
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// NOTE: for more info see docs for guaranteeEvents(..)
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function clearGuaranteedQueue(names){
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names = names == '*' ? Object.keys(this._guaranteed_queue)
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: typeof(names) == typeof('str') ? names.split(/\s+/g)
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: names
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var that = this
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names.forEach(function(name){
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if(name in that._guaranteed_queue){
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that._guaranteed_queue[name] = []
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}
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})
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return this
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}
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// Guarantee that every event handler gets every event...
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//
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// guaranteeEvents('event', emitter)
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// -> emitter
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//
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//
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// This will add a .clearGuarantedQueue(..) method to the emitter that
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// This will add a .clearGuaranteedQueue(..) method to the emitter that
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// will clear the event queue for a specific event.
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//
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// Clear event(s) queue(s)...
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// emitter.clearGuarantedQueue('event')
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// emitter.clearGuarantedQueue('eventA eventB ...')
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// emitter.clearGuarantedQueue(['eventA', 'eventB', ...])
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// emitter.clearGuaranteedQueue('event')
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// emitter.clearGuaranteedQueue('eventA eventB ...')
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// emitter.clearGuaranteedQueue(['eventA', 'eventB', ...])
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// -> emitter
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//
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// Clear all queues...
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// emitter.clearGuarantedQueue('*')
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// emitter.clearGuaranteedQueue('*')
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// -> emitter
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//
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//
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// NOTE: the seen stack might get quite big, this is not recommended for
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// long running emitters...
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//
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var guaranteeEvents =
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module.exports =
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function(names, emitter){
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function guaranteeEvents(names, emitter){
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names = typeof(names) == typeof('str') ? names.split(/\s+/g) : names
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// add ability to clear the queue...
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if(emitter.clearGuarantedQueue == null){
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emitter.clearGuarantedQueue = function(names){
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names = names == '*' ? Object.keys(this._guaranteed_queue)
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: typeof(names) == typeof('str') ? names.split(/\s+/g)
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: names
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var that = this
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names.forEach(function(name){
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if(name in that._guaranteed_queue){
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that._guaranteed_queue[name] = []
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}
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})
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return this
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}
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if(emitter.clearGuaranteedQueue == null){
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emitter.clearGuaranteedQueue = clearGuaranteedQueue
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emitter._guaranteed_queue = {}
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}
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@ -81,6 +86,10 @@ function(names, emitter){
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}
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// this is the only thing we are exporting...
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module.exports = guaranteeEvents
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/**********************************************************************
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* vim:set ts=4 sw=4 : */
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@ -1,6 +1,6 @@
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{
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"name": "guaranteeEvents",
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"version": "1.0.0",
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"name": "guarantee-events",
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"version": "1.0.6",
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"description": "Guarantee that every event handler gets every event...",
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"main": "index.js",
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"scripts": {
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@ -18,7 +18,7 @@
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"event"
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],
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"author": "Alex A. Naanou <alex.nanou@gmail.com> (https://github.com/flynx)",
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"license": "New BSD",
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"license": "BSD-3-Clause",
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"bugs": {
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"url": "https://github.com/flynx/guaranteeEvents/issues"
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},
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