README

Declarative state machine with guards, hooks, and transition history.

Requirements

PHP 8.2+

Installation

composer require philiprehberger/php-state-machine

Usage

Define a state machine

use PhilipRehberger\StateMachine\StateMachine;

$sm = StateMachine::define()
    ->states(['pending', 'processing', 'shipped', 'delivered', 'cancelled'])
    ->initial('pending')
    ->stateProperty('state')
    ->transition('process', 'pending', 'processing')
    ->transition('ship', 'processing', 'shipped')
    ->transition('deliver', 'shipped', 'delivered')
    ->transition('cancel', ['pending', 'processing'], 'cancelled')
    ->build();

Apply transitions

$order = new Order(); // $order->state === 'pending'

$result = $sm->apply($order, 'process');
// $order->state === 'processing'
// $result->from === 'pending'
// $result->to === 'processing'

Pass a payload to transitions

$sm = StateMachine::define()
    ->states(['pending', 'approved', 'rejected'])
    ->initial('pending')
    ->transition('approve', 'pending', 'approved')
        ->guard(fn (object $order, array $payload) => ($payload['role'] ?? '') === 'manager')
        ->before(fn (object $order, array $payload) => $order->log[] = 'Approved by '.$payload['user'])
    ->transition('reject', 'pending', 'rejected')
    ->build();

$sm->apply($order, 'approve', ['role' => 'manager', 'user' => 'Alice']);

The $payload array is passed through to all guards, before hooks, and after hooks. It defaults to [] when omitted, so existing guards and hooks that accept only one parameter continue to work.

Check if a transition is allowed

$sm->can($order, 'ship');    // true
$sm->can($order, 'deliver'); // false

Get available transitions

$sm->allowedTransitions($order); // ['ship', 'cancel']
$sm->availableTransitions($order); // ['ship', 'cancel'] (alias)

// Payload is forwarded to guards when checking availability:
$sm->availableTransitions($order, ['role' => 'manager']);

Guards

Guards are callables that must return true for the transition to proceed:

$sm = StateMachine::define()
    ->states(['pending', 'processing', 'shipped'])
    ->initial('pending')
    ->transition('process', 'pending', 'processing')
        ->guard(fn (object $order, array $payload) => $order->isPaid)
    ->transition('ship', 'processing', 'shipped')
    ->build();

Before and after hooks

$sm = StateMachine::define()
    ->states(['pending', 'processing'])
    ->initial('pending')
    ->transition('process', 'pending', 'processing')
        ->before(fn (object $order, array $payload) => $order->log[] = 'Processing started')
        ->after(fn (object $order, array $payload) => $order->log[] = 'Processing complete')
    ->build();

State entry/exit hooks

$sm = StateMachine::define()
    ->states(['draft', 'review', 'published'])
    ->initial('draft')
    ->onEnter('review', fn (object $entity, string $transition) => $entity->log[] = "Entered review via $transition")
    ->onExit('draft', fn (object $entity, string $transition) => $entity->log[] = "Left draft via $transition")
    ->transition('submit', 'draft', 'review')
    ->transition('approve', 'review', 'published')
    ->build();

Rollback the last transition

$sm->apply($order, 'process');
$sm->rollback($order);
// $order->state === 'pending'

Mermaid diagram export

echo $sm->toMermaid();
// stateDiagram-v2
//     [*] --> pending
//     pending --> processing : process
//     processing --> shipped : ship
//     shipped --> delivered : deliver
//     pending --> cancelled : cancel
//     processing --> cancelled : cancel

Transition history

$sm->apply($order, 'process');
$sm->apply($order, 'ship');

$history = $sm->history();
$history->all();  // [TransitionResult, TransitionResult]
$history->last(); // TransitionResult { transition: 'ship', from: 'processing', to: 'shipped' }

API

Method	Description
`StateMachine::define()`	Create a new `StateMachineBuilder`
`$sm->apply(object $entity, string $transition, array $payload = [])`	Apply a transition, returns `TransitionResult`
`$sm->can(object $entity, string $transition, array $payload = [])`	Check if a transition is allowed
`$sm->allowedTransitions(object $entity, array $payload = [])`	Get names of all allowed transitions
`$sm->availableTransitions(object $entity, array $payload = [])`	Alias for `allowedTransitions()`
`$sm->currentState(object $entity)`	Get the entity's current state
`$sm->rollback(object $entity)`	Revert the most recent transition
`$sm->toMermaid()`	Generate a Mermaid state diagram string
`$sm->history()`	Get the `TransitionHistory` instance
`$sm->initialState()`	Get the defined initial state
`$sm->states()`	Get all defined states

StateMachineBuilder

Method	Description
`->states(array $states)`	Define valid states
`->initial(string $state)`	Set the initial state
`->stateProperty(string $property)`	Set the entity property name (default: `'state'`)
`->onEnter(string $state, callable $hook)`	Register a hook that fires when entering a state
`->onExit(string $state, callable $hook)`	Register a hook that fires when leaving a state
`->transition(string $name, string\|array $from, string $to)`	Define a transition
`->build()`	Build the `StateMachine`

TransitionBuilder

Method	Description
`->guard(callable $guard)`	Add a guard `(object $entity, array $payload): bool`
`->before(callable $hook)`	Add a before-transition hook `(object $entity, array $payload): void`
`->after(callable $hook)`	Add an after-transition hook `(object $entity, array $payload): void`

Development

composer install
vendor/bin/phpunit
vendor/bin/pint --test

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License

MIT

philiprehberger/php-state-machine

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