Simple state machine with transitions

state-machine.js

'use strict';

var _ = require('lodash');

/**
 * @class StateMachine
 * @constructor
 */
function StateMachine(options) {
    /**
     * @type {Object}
     */
    this.options = options;

    /**
     * current state
     * @type {String}
     */
    this.currentState = options.state;

    /**
     * state transitions
     * @type {Object}
     */
    this.transitions = {};
}

/**
 * Returns the current state of the state machine
 * @method getState
 */
StateMachine.prototype.getState = function getState() {
    return this.currentState;
};

/**
 * merge into the internal transitions
 * @method addTransitions
 * @param {Object} transitions
 */
StateMachine.prototype.addTransitions = function addTransitions(transitions) {
    return _.extend(this.transitions, transitions);
};

/**
 * Update the current state and call the state transition method
 * @method changeState
 * @param {String} state
 */
StateMachine.prototype.changeState = function changeState() {
    // take the given state out of the arguments array
    var state = [].shift.apply(arguments);
    var context = this.options.context || null;

    if(!!this.transitions) {
        var transition = this.transitions[this.currentState + ' > ' + state];
        var fromTransition = this.transitions[this.currentState + ' >'];
        var toTransition = this.transitions['> ' + state];

        if (!!fromTransition) {
            fromTransition.apply(context, arguments);
        }

        if (!!transition) {
            transition.apply(context, arguments);
        }

        if (!!toTransition) {
            toTransition.apply(context, arguments);
        }
    }
    this.currentState = state;
};

module.exports = StateMachine;