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StateMachine.js
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StateMachine.js
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(function() {
//get rid of them slashes
var elementSelector = function(selector) {
return selector.split("/")[0];
}
//given a machine, find all of the elements it should manage.
var getElementSelectors = function(machine) {
var selectors = [];
machine.states.forEach(function(state) {
state.on.forEach(function(evt) {
selectors.push(elementSelector(evt.event));
});
});
return selectors.concat(machine.elements);
}
//A simple state machine. Follows states by transition.
var Machine = function(graph) {
//parse out the state map into a lookup table
this.stateMap = {};
var self = this;
graph.states.forEach(function(state) {
self.stateMap[state.state] = state;
});
graph.states.forEach(function(state) {
var ons = self.stateMap[state.state].on;
self.stateMap[state.state].lookup = {};
ons.forEach(function(on) {
self.stateMap[state.state].lookup[on.event] = self.stateMap[on.to];
});
});
this.currentState = graph.states[0]; //default to the first
function getTransition(state, key) {
return state.lookup[key];
}
this.transition = function(transitionKey) {
var transition = getTransition(this.currentState, transitionKey);
if (!transition) throw "Invalid transition for this state.";
this.currentState = transition;
return this.currentState;
}
}
//This object worries about interacting with the DOM.
//Handles setting the data-* attr, and binding events.
var DocumentManager = function(machineName, root, elementSelectors) {
var getParameters = function(text) {
var startAt = text.indexOf("(") + 1;
var stopAt = text.indexOf(")");
var res = text.substring(startAt, stopAt).split(",");
if (res[0] == "" && res.length == 1) return null;
return res;
}
var keypressRule = function(eventTag) {
var keys = getParameters(eventTag);
if (keys === null) return function() { return true; } //if they didn't supply params, every key works
return function(event) {
return keys.indexOf(event.keyCode + "") >= 0;
}
}
var mouseRule = function(eventTag) {
var buttons = getParameters(eventTag);
var mapped = [];
if (buttons === null) return function() { return true; }
return function(event) {
return buttons.indexOf(event.buttons + "") >= 0;
}
}
var ruleForEvent = function(eventTag) {
if (eventTag.indexOf("keypress") >= 0) {
keypressRule(eventTag);
} else if (eventTag.indexOf("mousedown") >= 0 || eventTag.indexOf("mouseup") >= 0) {
return mouseRule(eventTag);
}
return function() { return true; }
}
this.boundEvents = [];
this.bindEvents = function(state) {
var ons = state.on;
var self = this;
ons.forEach(function(on) {
var trigger = on.event;
if (trigger.indexOf("/") >= 0) { //this is event-based
var picked = trigger.split("/");
var element = root.querySelector(picked.shift());
if (element) {
picked.forEach(function(p) {
var actual = p.split("(")[0]; //this handles keybased events
self.bindEvent(element, actual, on.event, ruleForEvent(p));
});
}
}
});
}
this.bindEvent = function(element,event, nextState, rule) {
var bound = {
element:element, event:event, handler: function(evt) {
if (rule(evt))
CState.Machines[machineName].transition(nextState);
}
}
element.addEventListener(event, bound.handler);
this.boundEvents.push(bound);
}
this.unbindEvents = function() {
var ev;
while(ev = this.boundEvents.shift()) {
ev.element.removeEventListener(ev.event, ev.handler);
}
}
this.setState = function(newState) {
this.unbindEvents();
elementSelectors.forEach(function(es) {
var elems = root.querySelectorAll(elementSelector(es));
for (var j = 0; j < elems.length; j++) {
elems[j].setAttribute("data-" + machineName, newState.state);
}
});
this.bindEvents(newState);
}
}
//Facade that sits atop the Machine & DocManager
var StateMachine = function(rootElement, machine) {
var root = null;
if (typeof(rootElement) == "string") {
root = document.querySelector(rootElement);
} else {
root = rootElement;
}
this.Machine = new Machine(machine);
this.Document = new DocumentManager(machine.name, root, getElementSelectors(machine));
this.Document.bindEvents(this.Machine.currentState);
this.transition = function(transitionKey) {
var next = this.Machine.transition(transitionKey);
this.Document.setState(next);
}
};
//Wrapper to govern machines.
var Machines = function() {
this.Machines = [];
this.add = function(rootElement, machine) {
if (this.Machines[machine.name]) throw "Machine with this name already exists."
this.Machines[machine.name] = new StateMachine(rootElement, machine);
}
this.remove = function(name) {
this.Machines[name].unregister();
delete this.Machines[name];
}
}
window.CState = new Machines();
})();