Kristi

Kristi is an asynchronous finite state machine engine. It allows you to describe a program (or part of it) using an automata-based approach.

In addition, this is my first experiment with literate programming (with help of a literate-programming-lib).

Kristi is inspired by Machina.js library.

Usage

Import

Users of npm can use npm install kristi. In other case, use gulp build-min to get minified UMD-compatible build.

FSM Construction

import { Automaton, EVENTS } from 'kristi';
 
let fsm = new Automaton({
    'login-screen-is-shown': {
        transitions: {
            'user-authenticated'           : 'todo-screen-is-shown',
            'password-recovery-requested'  : 'password-recovery-screen-is-shown',
        },
        coming() {
            let fsm = this; // Automaton instance is set as `this` in `coming` and `leaving`;
 
            // AJAX requests for screen template, etc...
            return new Promise((resolve) => {
                $('#btn-recover-passw').click(() => {
                    fsm.processEvent('password-recovery-requested');
                });
 
                resolve();
            });
        },
 
        leaving() {
            // Some clean-up
        }
    },
 
    'todo-screen-is-shown' : {
        ...
    },
 
    ...
});
 
fsm.startWith('login-screen-is-shown');

The "best practice" is to move transition functions out of fsm-schema definition:

let fsm = new Automaton({
    'login-screen-is-shown': {
        transitions: {
            'user-authenticated'           : 'todo-screen-is-shown',
            'password-recovery-requested'  : 'password-recovery-screen-is-show',
        },
        coming:  showLoginScreen,
        leaving: hideLoginScreen
    }
    ...
});

Events

Kristi provides simple on/off interface, so you can subscribe to some events from fsm instance.

fsm.on(EVENTS.TRANSITION, ({from, to}) => {...});
 
fsm.on(EVENTS.PROCESSING, ({state, event}) => {...});

TODO: add full Event API description.

API

The full API description could be found here.

License

MIT-LICENSE