Add basic filter for PHP 8 attribute at class level

composer.json

@@ -24,6 +24,6 @@
     "require": {
         "php": ">=7.2",
         "nikic/php-parser": "^4",
-        "symfony/finder": "^4|^5"
+        "symfony/finder": "^4|^5|^6"
     }
 }

src/Iterator/ClassIterator.php

@@ -20,6 +20,7 @@
 use hanneskod\classtools\Iterator\Filter\NotFilter;
 use hanneskod\classtools\Iterator\Filter\TypeFilter;
 use hanneskod\classtools\Iterator\Filter\WhereFilter;
+use hanneskod\classtools\Iterator\Filter\AttributeFilter;
 use hanneskod\classtools\Exception\LogicException;
 use hanneskod\classtools\Loader\ClassLoader;
 use hanneskod\classtools\Exception\ReaderException;
@@ -144,6 +145,11 @@ public function cache(): Filter
         return $this->filter(new CacheFilter);
     }
 
+    public function attribute(string $attribute_class_name): Filter
+    {
+        return $this->filter(new AttributeFilter($attribute_class_name));
+    }
+
     public function transform(Writer $writer): string
     {
         $code = '';

src/Iterator/ClassIteratorInterface.php

@@ -84,6 +84,11 @@ public function not(Filter $filter): Filter;
      */
     public function cache(): Filter;
 
+	/**
+	 * Attribute iterator
+	 */
+	public function attribute(string $attribute_class_name): Filter;
+
     /**
      * Transform found classes
      */

src/Iterator/Filter/AttributeFilter.php

@@ -0,0 +1,68 @@
+<?php
+/**
+ * This program is free software. It comes without any warranty, to
+ * the extent permitted by applicable law. You can redistribute it
+ * and/or modify it under the terms of the Do What The Fuck You Want
+ * To Public License, Version 2, as published by Sam Hocevar. See
+ * http://www.wtfpl.net/ for more details.
+ */
+
+declare(strict_types = 1);
+
+namespace hanneskod\classtools\Iterator\Filter;
+
+use hanneskod\classtools\Iterator\ClassIterator;
+use hanneskod\classtools\Iterator\Filter;
+
+/**
+ * Filter classes based on presence of a PHP 8 attribute on a class level
+ * Note this is a basic implementation that simply looks for at least one declaration
+ * of a given attribute class and considers this a match
+ *
+ * Attribute class name must be passed, not an instance of the attribute
+ *
+ * #[Attribute]
+ * class CoolStuff { ... }
+ * 
+ * #[CoolStuff]
+ * class BeCool { ... }
+ *
+ * // Print all classes tagged with a CoolStuff attribute
+ * foreach ($iter->attribute(CoolStuff::class) as $class) {
+ *   echo $class->getName();
+ * }
+ *
+ * Note this works only in PHP 8.0.1 or higher, but syntax is PHP 7 compaptible
+ * so whilst this cannot be used on earlier versions it also won't break them
+ *
+ * @author Mark Hewitt <mark.hewitt@centurionsolutions.com.au>
+ */
+final class AttributeFilter extends ClassIterator implements Filter
+{
+    use FilterTrait;
+
+    /**
+     * @var string 
+     */
+    private $attribute_class_name;
+
+    /**
+     * Register matching attribute name
+     */
+    public function __construct(string $attribute_class_name)
+    {
+        parent::__construct();
+        $this->attribute_class_name = $attribute_class_name;
+    }
+
+    public function getIterator(): iterable
+    {
+        foreach ($this->getBoundIterator() as $className => $reflectedClass) {
+			// if the class implements the given attribute (one or more times)
+			// then this is a match, and we yield with the found class
+            if ( !empty($reflectedClass->getAttributes($this->attribute_class_name, \ReflectionAttribute::IS_INSTANCEOF)) ) {
+                yield $className => $reflectedClass;
+            }
+        }
+    }
+}

tests/Iterator/ClassIteratorTest.php

@@ -246,6 +246,79 @@ public function testCacheFilter()
         );
     }
 
+    public function testAttributeFilter()
+    {
+		if ( version_compare(PHP_VERSION, '8.0.1') >= 0) {
+
+			# define our own system under test, adding attributes etc to standard test will break 
+			# tests for minimize etc
+			MockFinder::setIterator(
+								new \ArrayIterator([
+									new MockSplFileInfo(''),
+									new MockSplFileInfo('<?php #[Attribute] class NotUsed {  }'),
+									new MockSplFileInfo('<?php #[Attribute] class CoolStuff {  }'),
+									new MockSplFileInfo('<?php #[Attribute] class EvenCoolerStuff {  }'),
+									new MockSplFileInfo('<?php #[Attribute] class WayCool extends CoolStuff {  }'),
+									new MockSplFileInfo('<?php #[CoolStuff] class BeCool { }'),
+									new MockSplFileInfo("<?php #[EvenCoolerStuff]\n#[CoolStuff]\nclass TheCoolest { }"),
+									new MockSplFileInfo('<?php #[WayCool] class InheritedCoolness {}'),
+									new MockSplFileInfo('<?php class NotCool {}')
+								])
+							);
+
+			$classIterator = new ClassIterator(new MockFinder);
+			$classIterator->enableAutoloading();
+
+			// look for class tagged with 'CoolStuff'
+			// we should find both BeCool, TheCoolest  and WayCool because filter uses instance inheritance
+			// by default, thus WayCool extends CoolStuff and is detect by this filter
+			$result = iterator_to_array(
+				$classIterator->attribute('CoolStuff')
+			);
+			$this->assertArrayHasKey(
+				'BeCool',
+				$result
+			);
+			$this->assertArrayHasKey(
+				'TheCoolest',
+				$result
+			);
+			$this->assertArrayHasKey(
+				'InheritedCoolness',
+				$result
+			);
+			$this->assertCount(
+				3,
+				$result
+			);
+
+			// look for class tagged with 'EvenCoolerStuff'
+			// we should find only TheCoolest
+			$result = iterator_to_array(
+				$classIterator->attribute('EvenCoolerStuff')
+			);
+			$this->assertArrayHasKey(
+				'TheCoolest',
+				$result
+			);
+			$this->assertCount(
+				1,
+				$result
+			);
+
+			// look for an attribute not tagged onto anything, should return empty
+			$result = iterator_to_array(
+				$classIterator->attribute('NotUsed')
+			);
+			$this->assertEmpty(
+				$result
+			);
+
+		} else {
+			$this->markTestSkipped('This test requires PHP 8.0.1 or higher');
+		}
+    }
+
     public function testMinimize()
     {