Add php8.1 enum support

spec/SM/DummyEnumState.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace spec\SM;
+
+if (version_compare(PHP_VERSION, '8.1', '>=')) {
+    enum DummyEnumState: string
+    {
+        case Checkout = 'checkout';
+        case Pending = 'pending';
+        case Confirmed = 'confirmed';
+        case Cancelled = 'cancelled';
+    }
+} else {
+    class DummyEnumState
+    {
+        const Checkout = 'checkout';
+        const Pending = 'pending';
+        const Confirmed = 'confirmed';
+        const Cancelled = 'cancelled';
+    }
+}

spec/SM/StateMachine/StateMachineSpec.php

@@ -2,6 +2,7 @@
 
 namespace spec\SM\StateMachine;
 
+use PhpSpec\Exception\Example\SkippingException;
 use PhpSpec\ObjectBehavior;
 use Prophecy\Argument;
 use SM\Callback\CallbackFactoryInterface;
@@ -208,4 +209,47 @@ function it_returns_possible_transitions($object, $callbackFactory, CallbackInte
 
         $this->getPossibleTransitions()->shouldReturn(array('create', 'confirm'));
     }
+
+
+
+    function it_should_return_back_enum_value($object)
+    {
+        if (version_compare(PHP_VERSION, '8.1', '<')) {
+            return;
+        }
+
+        $object->getState()->shouldBeCalled()->willReturn(\spec\SM\DummyEnumState::Checkout);
+        $this->setEnumClass(\spec\SM\DummyEnumState::class);
+        $state = \spec\SM\DummyEnumState::Checkout;
+
+        if (property_exists($state, 'value')) {
+            $this->getState()->shouldReturn($state->value);
+        }
+    }
+
+    function it_throws_exeception_if_enum_class_in_not_backed($object)
+    {
+        if (version_compare(PHP_VERSION, '8.1', '<')) {
+            return;
+        }
+
+        $this->shouldThrow(SMException::class)->during('setEnumClass', array('dummy_string'));
+    }
+
+    function it_not_throws_an_exception_during_apply_when_state_is_back_enum($object, $callbackFactory, CallbackInterface $guard, $dispatcher)
+    {
+        $this->checkPhpMinimumVersion('8.1');
+
+        $object->getState()->shouldBeCalled()->willReturn(\spec\SM\DummyEnumState::Checkout);
+        $this->setEnumClass(\spec\SM\DummyEnumState::class);
+        $dispatcher->dispatch(Argument::any())->shouldNotBeCalled();
+        $this->shouldNotThrow(SMException::class)->during('apply', array(\spec\SM\DummyEnumState::Pending));
+    }
+
+    private function checkPhpMinimumVersion($version)
+    {
+        if (version_compare(PHP_VERSION, $version, '<')) {
+            throw new SkippingException(sprintf("Minimum php version: %s", $version));
+        }
+    }
 }

src/SM/StateMachine/StateMachine.php

@@ -35,6 +35,9 @@ class StateMachine implements StateMachineInterface
     /** @var CallbackFactoryInterface */
     protected $callbackFactory;
 
+    /** @var ?string */
+    protected $enumClass;
+
     /**
      * @param object                   $object          Underlying object for the state machine
      * @param array                    $config          Config array of the graph
@@ -59,6 +62,8 @@ public function __construct(
 
         $this->config = $config;
 
+        $this->setEnumClass($config['enumClass'] ?? null);
+
         // Test if the given object has the given state property path
         if (!$this->hasObjectProperty($object, $config['property_path'])) {
             throw new SMException(sprintf(
@@ -147,7 +152,13 @@ public function apply(string $transition, $soft = false): bool
     public function getState(): string
     {
         $accessor = new PropertyAccessor();
-        return $accessor->getValue($this->object, $this->config['property_path']);
+        $state = $accessor->getValue($this->object, $this->config['property_path']);
+
+        if (($enumClass = $this->getEnumClass()) && is_a($state, $enumClass, true)) {
+            return (string) $state->value;
+        }
+
+        return $state;
     }
 
     /**
@@ -195,6 +206,10 @@ protected function setState($state): void
             ));
         }
 
+        if ($enumClass = $this->getEnumClass()) {
+            $state = $enumClass::from($state);
+        }
+
         $accessor = new PropertyAccessor();
         $accessor->setValue($this->object, $this->config['property_path'], $state);
     }
@@ -223,4 +238,20 @@ protected function hasObjectProperty($object, string $property): bool
     {
         return (new PropertyAccessor())->isReadable($object, $property);
     }
+
+    public function getEnumClass(): ?string
+    {
+        return $this->enumClass;
+    }
+
+    public function setEnumClass(?string $class): self
+    {
+        if ($class && !is_a($class, \BackedEnum::class, true)) {
+            throw new SMException('Enum class must be a BackedEnum');
+        }
+
+        $this->enumClass = $class;
+
+        return $this;
+    }
 }