add find-and-register functionality to the processor factory

composer.json

@@ -16,6 +16,7 @@
   "require-dev": {
     "doctrine/annotations": "~1.2",
     "doctrine/cache": "^1.4",
+    "kcs/class-finder": "^0.1",
     "mikey179/vfsstream": "^1.6",
     "phpunit/phpunit": "^8.0",
     "psr/event-dispatcher": "^1.0",

lib/Loader/Processor/Annotation/Processor.php

@@ -0,0 +1,19 @@
+<?php declare(strict_types=1);
+
+namespace Kcs\Metadata\Loader\Processor\Annotation;
+
+use Doctrine\Common\Annotations\Annotation\Required;
+
+/**
+ * @Annotation()
+ * @Target({"CLASS"})
+ */
+class Processor
+{
+    /**
+     * @var string
+     *
+     * @Required()
+     */
+    public $annotation;
+}

lib/Loader/Processor/ProcessorFactory.php

@@ -2,12 +2,15 @@
 
 namespace Kcs\Metadata\Loader\Processor;
 
+use Doctrine\Common\Annotations\AnnotationReader;
+use Kcs\ClassFinder\Finder\RecursiveFinder;
 use Kcs\Metadata\Exception\InvalidArgumentException;
+use Kcs\Metadata\Loader\Processor\Annotation\Processor;
 
 class ProcessorFactory implements ProcessorFactoryInterface
 {
     /**
-     * @var string[]
+     * @var string[][]
      */
     private $processors = [];
 
@@ -37,6 +40,31 @@ public function registerProcessor(string $class, string $processorClass): void
         }
     }
 
+    /**
+     * Finds and register annotation processors recursively.
+     *
+     * @param string $dir
+     */
+    public function registerProcessors(string $dir): void
+    {
+        if (! \class_exists(RecursiveFinder::class)) {
+            throw new \RuntimeException('Cannot find processors as the kcs/class-finder package is not installed.');
+        }
+
+        $reader = new AnnotationReader();
+        $finder = new RecursiveFinder($dir);
+        $finder
+            ->annotatedBy(Processor::class)
+            ->implementationOf(ProcessorInterface::class);
+
+        /** @var \ReflectionClass $reflClass */
+        foreach ($finder as $reflClass) {
+            /** @var Processor $annot */
+            $annot = $reader->getClassAnnotation($reflClass, Processor::class);
+            $this->registerProcessor($annot->annotation, $reflClass->getName());
+        }
+    }
+
     /**
      * {@inheritdoc}
      */

tests/Fixtures/AnnotationProcessorLoader/Processor/ClassAnnotProcessor.php

@@ -0,0 +1,18 @@
+<?php declare(strict_types=1);
+
+namespace Kcs\Metadata\Tests\Fixtures\AnnotationProcessorLoader\Processor;
+
+use Kcs\Metadata\Loader\Processor\Annotation\Processor;
+use Kcs\Metadata\Loader\Processor\ProcessorInterface;
+use Kcs\Metadata\MetadataInterface;
+use Kcs\Metadata\Tests\Fixtures\AnnotationProcessorLoader\Annotation\ClassAnnot;
+
+/**
+ * @Processor(annotation=ClassAnnot::class)
+ */
+class ClassAnnotProcessor implements ProcessorInterface
+{
+    public function process(MetadataInterface $metadata, $subject): void
+    {
+    }
+}

tests/Loader/Processor/ProcessorFactoryTest.php

@@ -2,14 +2,19 @@
 
 namespace Kcs\Metadata\Tests\Loader\Processor;
 
+use Doctrine\Common\Annotations\AnnotationRegistry;
 use Kcs\Metadata\Exception\InvalidArgumentException;
 use Kcs\Metadata\Loader\Processor\CompositeProcessor;
 use Kcs\Metadata\Loader\Processor\ProcessorFactory;
 use Kcs\Metadata\Loader\Processor\ProcessorInterface;
 use Kcs\Metadata\MetadataInterface;
 use Kcs\Metadata\Tests\Fixtures\Annotation;
+use Kcs\Metadata\Tests\Fixtures\AnnotationProcessorLoader\Annotation\ClassAnnot;
+use Kcs\Metadata\Tests\Fixtures\AnnotationProcessorLoader\Processor\ClassAnnotProcessor;
 use PHPUnit\Framework\TestCase;
 
+AnnotationRegistry::registerLoader('class_exists');
+
 class FakeProcessor implements ProcessorInterface
 {
     public function process(MetadataInterface $metadata, $subject): void
@@ -91,4 +96,15 @@ public function get_processor_returns_composite_processor_if_more_than_one_proce
 
         self::assertInstanceOf(CompositeProcessor::class, $factory->getProcessor(Annotation::class));
     }
+
+    /**
+     * @test
+     */
+    public function register_processors_should_find_and_register_annotated_processors()
+    {
+        $factory = new ProcessorFactory();
+        $factory->registerProcessors(__DIR__.'/../../Fixtures/AnnotationProcessorLoader/Processor');
+
+        self::assertInstanceOf(ClassAnnotProcessor::class, $factory->getProcessor(ClassAnnot::class));
+    }
 }