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Add async/ await support #206

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Add async/ await support #206

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326 changes: 168 additions & 158 deletions src/jsm.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,171 +7,181 @@ var mixin = require('./util/mixin'),
//-------------------------------------------------------------------------------------------------

function JSM(context, config) {
this.context = context;
this.config = config;
this.state = config.init.from;
this.observers = [context];
this.context = context;
this.config = config;
this.state = config.init.from;
this.observers = [context];
}

//-------------------------------------------------------------------------------------------------

mixin(JSM.prototype, {

init: function(args) {
mixin(this.context, this.config.data.apply(this.context, args));
plugin.hook(this, 'init');
if (this.config.init.active)
return this.fire(this.config.init.name, []);
},

is: function(state) {
return Array.isArray(state) ? (state.indexOf(this.state) >= 0) : (this.state === state);
},

isPending: function() {
return this.pending;
},

can: function(transition) {
return !this.isPending() && !!this.seek(transition);
},

cannot: function(transition) {
return !this.can(transition);
},

allStates: function() {
return this.config.allStates();
},

allTransitions: function() {
return this.config.allTransitions();
},

transitions: function() {
return this.config.transitionsFor(this.state);
},

seek: function(transition, args) {
var wildcard = this.config.defaults.wildcard,
entry = this.config.transitionFor(this.state, transition),
to = entry && entry.to;
if (typeof to === 'function')
return to.apply(this.context, args);
else if (to === wildcard)
return this.state
else
return to
},

fire: function(transition, args) {
return this.transit(transition, this.state, this.seek(transition, args), args);
},

transit: function(transition, from, to, args) {

var lifecycle = this.config.lifecycle,
changed = this.config.options.observeUnchangedState || (from !== to);

if (!to)
return this.context.onInvalidTransition(transition, from, to);

if (this.isPending())
return this.context.onPendingTransition(transition, from, to);

this.config.addState(to); // might need to add this state if it's unknown (e.g. conditional transition or goto)

this.beginTransit();

args.unshift({ // this context will be passed to each lifecycle event observer
transition: transition,
from: from,
to: to,
fsm: this.context
});

return this.observeEvents([
this.observersForEvent(lifecycle.onBefore.transition),
this.observersForEvent(lifecycle.onBefore[transition]),
changed ? this.observersForEvent(lifecycle.onLeave.state) : UNOBSERVED,
changed ? this.observersForEvent(lifecycle.onLeave[from]) : UNOBSERVED,
this.observersForEvent(lifecycle.on.transition),
changed ? [ 'doTransit', [ this ] ] : UNOBSERVED,
changed ? this.observersForEvent(lifecycle.onEnter.state) : UNOBSERVED,
changed ? this.observersForEvent(lifecycle.onEnter[to]) : UNOBSERVED,
changed ? this.observersForEvent(lifecycle.on[to]) : UNOBSERVED,
this.observersForEvent(lifecycle.onAfter.transition),
this.observersForEvent(lifecycle.onAfter[transition]),
this.observersForEvent(lifecycle.on[transition])
], args);
},

beginTransit: function() { this.pending = true; },
endTransit: function(result) { this.pending = false; return result; },
failTransit: function(result) { this.pending = false; throw result; },
doTransit: function(lifecycle) { this.state = lifecycle.to; },

observe: function(args) {
if (args.length === 2) {
var observer = {};
observer[args[0]] = args[1];
this.observers.push(observer);
init: async function (args) {
mixin(this.context, this.config.data.apply(this.context, args));
plugin.hook(this, 'init');
if (this.config.init.active)
return await this.fire(this.config.init.name, []);
},

is: function (state) {
return Array.isArray(state) ? (state.indexOf(this.state) >= 0) : (this.state === state);
},

isPending: function () {
return this.pending;
},

can: function (transition) {
return !this.isPending() && !!this.seek(transition);
},

cannot: function (transition) {
return !this.can(transition);
},

allStates: function () {
return this.config.allStates();
},

allTransitions: function () {
return this.config.allTransitions();
},

transitions: function () {
return this.config.transitionsFor(this.state);
},

seek: function (transition, args) {
var wildcard = this.config.defaults.wildcard,
entry = this.config.transitionFor(this.state, transition),
to = entry && entry.to;
if (typeof to === 'function')
return to.apply(this.context, args);
else if (to === wildcard)
return this.state
else
return to
},

fire: async function (transition, args) {
let r = await this.transit(transition, this.state, this.seek(transition, args), args);
return r;
},

transit: async function (transition, from, to, args) {

var lifecycle = this.config.lifecycle,
changed = this.config.options.observeUnchangedState || (from !== to);

if (!to)
return this.context.onInvalidTransition(transition, from, to);

if (this.isPending())
return this.context.onPendingTransition(transition, from, to);

this.config.addState(to); // might need to add this state if it's unknown (e.g. conditional transition or goto)

this.beginTransit();

args.unshift({ // this context will be passed to each lifecycle event observer
transition: transition,
from: from,
to: to,
fsm: this.context
});

let r = await this.observeEvents([
this.observersForEvent(lifecycle.onBefore.transition),
this.observersForEvent(lifecycle.onBefore[transition]),
changed ? this.observersForEvent(lifecycle.onLeave.state) : UNOBSERVED,
changed ? this.observersForEvent(lifecycle.onLeave[from]) : UNOBSERVED,
this.observersForEvent(lifecycle.on.transition),
changed ? ['doTransit', [this]] : UNOBSERVED,
changed ? this.observersForEvent(lifecycle.onEnter.state) : UNOBSERVED,
changed ? this.observersForEvent(lifecycle.onEnter[to]) : UNOBSERVED,
changed ? this.observersForEvent(lifecycle.on[to]) : UNOBSERVED,
this.observersForEvent(lifecycle.onAfter.transition),
this.observersForEvent(lifecycle.onAfter[transition]),
this.observersForEvent(lifecycle.on[transition])
], args);
return r;
},

beginTransit: function () { this.pending = true; },
endTransit: function (result) { this.pending = false; return result; },
failTransit: function (result) { this.pending = false; throw result; },
doTransit: function (lifecycle) { this.state = lifecycle.to; },

observe: function (args) {
if (args.length === 2) {
var observer = {};
observer[args[0]] = args[1];
this.observers.push(observer);
}
else {
this.observers.push(args[0]);
}
},

observersForEvent: function (event) { // TODO: this could be cached
var n = 0, max = this.observers.length, observer, result = [];
for (; n < max; n++) {
observer = this.observers[n];
if (observer[event])
result.push(observer);
}
return [event, result, true]
},

observeEvents: async function (events, args, previousEvent, previousResult) {
if (events.length === 0) {
return this.endTransit(previousResult === undefined ? true : previousResult);
}

var event = events[0][0],
observers = events[0][1],
pluggable = events[0][2];

args[0].event = event;
if (event && pluggable && event !== previousEvent)
plugin.hook(this, 'lifecycle', args);

if (observers.length === 0) {
events.shift();
return await this.observeEvents(events, args, event, previousResult);
}
else {
var observer = observers.shift();
let result = true;

if (observer[event].constructor.name === 'AsyncFunction') {
result = await observer[event].apply(observer, args);
}
else {
result = observer[event].apply(observer, args);
}

if (result && typeof result.then === 'function') {
result = await result.then((r) => r).catch((f) => false);
}

if (result === false) {
return this.endTransit(false);
}
else {
return await this.observeEvents(events, args, event, result);
}
}
},

onInvalidTransition: function (transition, from, to) {
throw new Exception("transition is invalid in current state", transition, from, to, this.state);
},

onPendingTransition: function (transition, from, to) {
throw new Exception("transition is invalid while previous transition is still in progress", transition, from, to, this.state);
}
else {
this.observers.push(args[0]);
}
},

observersForEvent: function(event) { // TODO: this could be cached
var n = 0, max = this.observers.length, observer, result = [];
for( ; n < max ; n++) {
observer = this.observers[n];
if (observer[event])
result.push(observer);
}
return [ event, result, true ]
},

observeEvents: function(events, args, previousEvent, previousResult) {
if (events.length === 0) {
return this.endTransit(previousResult === undefined ? true : previousResult);
}

var event = events[0][0],
observers = events[0][1],
pluggable = events[0][2];

args[0].event = event;
if (event && pluggable && event !== previousEvent)
plugin.hook(this, 'lifecycle', args);

if (observers.length === 0) {
events.shift();
return this.observeEvents(events, args, event, previousResult);
}
else {
var observer = observers.shift(),
result = observer[event].apply(observer, args);
if (result && typeof result.then === 'function') {
return result.then(this.observeEvents.bind(this, events, args, event))
.catch(this.failTransit.bind(this))
}
else if (result === false) {
return this.endTransit(false);
}
else {
return this.observeEvents(events, args, event, result);
}
}
},

onInvalidTransition: function(transition, from, to) {
throw new Exception("transition is invalid in current state", transition, from, to, this.state);
},

onPendingTransition: function(transition, from, to) {
throw new Exception("transition is invalid while previous transition is still in progress", transition, from, to, this.state);
}

});

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