XState - State Machine for PHP

XState is a state machine library to play with any complex behavior of your PHP objects (inspired by xstate.js)

Installation

The recommended way to install Xstate is through Composer

composer require mouadziani/xstate

Define state machine workflow

Let's say we want to define a state machine workflow for a video object, generally a video may have 3 states (playing, stopped, paused),

as a first step you have to create a new object from StateMachine class

use \Mouadziani\XState\StateMachine;

$video = StateMachine::make();

Then you have to define the allowed states as well as the default state

$video
    ->defaultState('stopped')
    ->states(['playing', 'stopped', 'paused']);

And finally the transitions

use \Mouadziani\XState\Transition;

$video->transitions([
    new Transition('PLAY', ['stopped', 'paused'], 'playing'),
    new Transition('STOP', 'playing', 'stopped'),
    new Transition('PAUSE', 'playing', 'paused'),
    new Transition('RESUME', 'paused', 'playing'),
]);

The Transition class expect 3 required params:

• Trigger: As a name of the transition which will be used to trigger a specific transition (should be unique)
• From: Expect a string for a single / or array for multiple initial allowed states
• To: Expect string which is the next target state (should match one of the defined allowed states)

Guards (optional)

You can either define a guard callback for a specific transition using guard method, which must return a bool. If a guard returns false, the transition cannot be performed.

use \Mouadziani\XState\Transition;

$video->transitions([
    (new Transition('PLAY', ['stopped', 'paused'], 'playing'))
        ->guard(function ($from, $to) {
            return true;
        })
]);

💡 You can define the whole workflow using a single statement:

$video = StateMachine::make()
    ->defaultState('playing')
    ->states(['playing', 'stopped', 'paused'])
    ->transitions([
        new Transition('PLAY', ['stopped', 'paused'], 'playing'),
        new Transition('STOP', 'playing', 'stopped'),
        new Transition('PAUSE', 'playing', 'paused'),
    ]);

Work with states & transitions

Trigger transition

There are two ways to trigger a specific defined transition

1- Using transitionTo method and specify the name of the transition as an argument

$video->transitionTo('PLAY');

2- Or just calling the name of the transition from your machine object as a method

$video->play();

Occasionally triggering a transition may throw an exception if the target transition is not defined /or not allowed:

use \Mouadziani\XState\Exceptions;

try {
    $video->transitionTo('RESUME');
} catch (Exceptions\TransitionNotDefinedException $ex) {
    // the target transition is not defined
} catch (Exceptions\TransitionNotAllowedException $ex) {
    // the target transition is not allowed
}

Get the current state

echo $video->currentState(); // playing

Get the allowed transitions

$video->allowedTransitions(); // ['STOP', 'PAUSE']

Adding in-demand transition

$video->addTransition(new Transition('TURN_OFF', 'playing', 'stopped'));

Upcoming features

• Add the ability to define guard for a specific transition
• Define/handle hooks before/after triggering transition

Testing

composer test

Security Vulnerabilities

Please review our security policy on how to report security vulnerabilities.

Credits

• Mouad Ziani
• All Contributors

License

The MIT License (MIT). Please see License File for more information.

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