Created
July 9, 2013 20:31
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Node JS finite state machine
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var U = require('underscore'); | |
var sites = [ | |
{"name" : "a", "time":4 }, | |
{"name" : "b", "time":5 }, | |
{"name" : "c", "time":6 }, | |
{"name" : "d", "time":7 }, | |
{"name" : "e", "time":8 }, | |
{"name" : "f", "time":9 } | |
]; | |
var currentSite = null; | |
var flowDef = { | |
"start" : "ready", | |
"transitions" : [ | |
{ | |
"from" : "ready", | |
"to" : "processing", | |
"action" : function() { | |
currentSite = sites.pop(); | |
console.log("processing site", currentSite); | |
setTimeout(function() { console.log('timeout done'); wf.processEvent('job_complete'); }, currentSite.time * 200); | |
}, | |
"guard" : function() { | |
return sites.length > 0; | |
} | |
}, | |
{ | |
"from" : "ready", | |
"to" : "done", | |
"guard" : function() { sites.length == 0; }, | |
"action" : function() { process.exit(0); } | |
}, | |
{ | |
"from" : "processing", | |
"to" : "ready", | |
"event" : "job_complete", | |
"action" : function() { | |
console.log("job complete"); | |
} | |
} | |
] | |
} | |
function Workflow(flow) { | |
this.flow = flow; | |
this.current = flow.start; | |
this.enterStartState = function() { | |
} | |
this.processEvent = function(eventName) { | |
console.log('processEvent(' + eventName + ')'); | |
while (true) { | |
var foundTransition = false; | |
var relevant = this.findRelevant(eventName); | |
if ( relevant.length > 0 ) { | |
this.current = relevant[0].to; | |
eventName = undefined; | |
/* if an action is called then it could publish an event */ | |
if ( U.has(relevant[0], 'action') ) { | |
relevant[0].action(); | |
} | |
} else { | |
return; | |
} | |
} | |
}; | |
this.findRelevant = function(eventName) { | |
var filter = { "from" : this.current }; | |
if ( eventName != undefined > 0 ) { | |
filter.event = eventName; | |
} | |
var relevant = U.where(this.flow.transitions, filter); | |
var unguarded = U.filter(relevant, function(item) { return (! U.has(item, 'guard')) || item.guard(); }); | |
return unguarded; | |
} | |
} | |
var wf = new Workflow(flowDef); | |
wf.processEvent(); | |
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