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/**
* wp.media.controller.StateMachine
*
* A state machine keeps track of state. It is in one state at a time,
* and can change from one state to another.
*
* States are stored as models in a Backbone collection.
*
* @memberOf wp.media.controller
*
* @since 3.5.0
*
* @class
* @augments Backbone.Model
* @mixin
* @mixes Backbone.Events
*/
var StateMachine = function() {
return {
// Use Backbone's self-propagating `extend` inheritance method.
extend: Backbone.Model.extend
};
};
_.extend( StateMachine.prototype, Backbone.Events,/** @lends wp.media.controller.StateMachine.prototype */{
/**
* Fetch a state.
*
* If no `id` is provided, returns the active state.
*
* Implicitly creates states.
*
* Ensure that the `states` collection exists so the `StateMachine`
* can be used as a mixin.
*
* @since 3.5.0
*
* @param {string} id
* @return {wp.media.controller.State} Returns a State model from
* the StateMachine collection.
*/
state: function( id ) {
this.states = this.states || new Backbone.Collection();
// Default to the active state.
id = id || this._state;
if ( id && ! this.states.get( id ) ) {
this.states.add({ id: id });
}
return this.states.get( id );
},
/**
* Sets the active state.
*
* Bail if we're trying to select the current state, if we haven't
* created the `states` collection, or are trying to select a state
* that does not exist.
*
* @since 3.5.0
*
* @param {string} id
*
* @fires wp.media.controller.State#deactivate
* @fires wp.media.controller.State#activate
*
* @return {wp.media.controller.StateMachine} Returns itself to allow chaining.
*/
setState: function( id ) {
var previous = this.state();
if ( ( previous && id === previous.id ) || ! this.states || ! this.states.get( id ) ) {
return this;
}
if ( previous ) {
previous.trigger('deactivate');
this._lastState = previous.id;
}
this._state = id;
this.state().trigger('activate');
return this;
},
/**
* Returns the previous active state.
*
* Call the `state()` method with no parameters to retrieve the current
* active state.
*
* @since 3.5.0
*
* @return {wp.media.controller.State} Returns a State model from
* the StateMachine collection.
*/
lastState: function() {
if ( this._lastState ) {
return this.state( this._lastState );
}
}
});
// Map all event binding and triggering on a StateMachine to its `states` collection.
_.each([ 'on', 'off', 'trigger' ], function( method ) {
/**
* @function on
* @memberOf wp.media.controller.StateMachine
* @instance
* @return {wp.media.controller.StateMachine} Returns itself to allow chaining.
*/
/**
* @function off
* @memberOf wp.media.controller.StateMachine
* @instance
* @return {wp.media.controller.StateMachine} Returns itself to allow chaining.
*/
/**
* @function trigger
* @memberOf wp.media.controller.StateMachine
* @instance
* @return {wp.media.controller.StateMachine} Returns itself to allow chaining.
*/
StateMachine.prototype[ method ] = function() {
// Ensure that the `states` collection exists so the `StateMachine`
// can be used as a mixin.
this.states = this.states || new Backbone.Collection();
// Forward the method to the `states` collection.
this.states[ method ].apply( this.states, arguments );
return this;
};
});
module.exports = StateMachine;
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