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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!
[](https://travis-ci.org/winzou/state-machine)
Installation (via composer)
---------------
```js
{
"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:
```php
$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](https://github.com/winzou/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](https://github.com/yohang/Finite), but has taken another direction.
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