A very lightweight yet powerful PHP state machine

Define your states, define your transitions and your callbacks: we do the rest. The era of hard-coded states is over!

Installation (via composer)

{
    "require": {
        "winzou/state-machine": "~0.1"
    }
}

Usage

Configure a state machine graph

In order to use the state machine, you first need to define a graph. A graph is a definition of states, transitions and optionnally callbacks ; all attached on an object from your domain. Multiple graphes can be attached to the same object.

Let's define a graph called myGraphA for our DomainObject object:

$config = array(
    'graph'         => 'myGraphA', // Name of the current graph - there can be many of them attached to the same object
    'property_path' => 'stateA',  // Property path of the object actually holding the state
    'states'        => array(
        'checkout',
        'pending',
        'confirmed',
        'cancelled'
    ),
    'transitions' => array(
        'create' => array(
            'from' => array('checkout'),
            'to'   => 'pending'
        ),
        'confirm' => array(
            'from' => array('checkout', 'pending'),
            'to'   => 'confirmed'
        ),
        'cancel' => array(
            'from' => array('confirmed'),
            'to'   => 'cancelled'
        )
    ),
    'callbacks' => array(
        'guard' => array(
            'guard-cancel' => array(
                'to' => array('cancelled'), // Will be called only for transitions going to this state
                'do' => function() { var_dump('guarding to cancelled state'); return false; }
            )
        ),
        'before' => array(
            'from-checkout' => array(
                'from' => array('checkout'), // Will be called only for transitions coming from this state
                'do'   => function() { var_dump('from checkout transition'); }
            )
        ),
        'after' => array(
            'on-confirm' => array(
                'on' => array('confirm'), // Will be called only on this transition
                'do' => function() { var_dump('on confirm transition'); }
            ),
            'to-cancelled' => array(
                'to' => array('cancelled'), // Will be called only for transitions going to this state
                'do' => function() { var_dump('to cancel transition'); }
            ),
            'cancel-date' => array(
                'to' => array('cancelled'),
                'do' => array('object', 'setCancelled'),
            ),
        )
    )
);

So, in the previous example, the graph has 6 possible states, and those can be achieved by applying some transitions to the object. For example, when creating a new DomainObject, you would apply the 'create' transition to the object, and after that the state of it would become pending.

Using the state machine

Definitions

The state machine is the object actually manipulating your object. By using the state machine you can test if a transition can be applied, actually apply a transition, retrieve the current state, etc. A state machine is specific to a couple object + graph. It means that if you want to manipulate another object, or the same object with another graph, you need another state machine.

The factory helps you to get the state machine for these couples object + graph. You give an object and a graph name to it, and it will return you the state machine for this couple. If you want to have this factory as a service in your Symfony2 application, please see the corresponding StateMachineBundle.

Usage

Please refer to the several examples in the examples folder.

Callbacks

Callbacks are used to guard transitions or execute some code before or after applying transitions.

Guarding callbacks must return a bool. If a guard returns false, a transition cannot be performed.

Credits

This library has been highly inspired by https://github.com/yohang/Finite, but has taken another direction.