[OptionsResolver] Made the OptionsResolver clonable

src/Symfony/Component/OptionsResolver/OptionsResolver.php

@@ -67,6 +67,14 @@ class OptionsResolver implements OptionsResolverInterface
         $this->defaultOptions = new Options();
     }
 
+    /**
+     * Clones the resolver.
+     */
+    public function __clone()
+    {
+        $this->defaultOptions = clone $this->defaultOptions;
+    }
+
     /**
      * {@inheritdoc}
      */
@@ -210,7 +218,7 @@ class OptionsResolver implements OptionsResolverInterface
     /**
      * {@inheritdoc}
      */
-    public function resolve(array $options)
+    public function resolve(array $options = array())
     {
         $this->validateOptionsExistence($options);
         $this->validateOptionsCompleteness($options);

src/Symfony/Component/OptionsResolver/OptionsResolverInterface.php

@@ -206,5 +206,5 @@ interface OptionsResolverInterface
      * @throws Exception\OptionDefinitionException If a cyclic dependency is detected
      *                                             between two lazy options.
      */
-    public function resolve(array $options);
+    public function resolve(array $options = array());
 }

src/Symfony/Component/OptionsResolver/Tests/OptionsResolverTest.php

@@ -612,4 +612,25 @@ class OptionsResolverTest extends \PHPUnit_Framework_TestCase
 
         $this->assertEquals($options, $this->resolver->resolve($options));
     }
+
+    public function testClone()
+    {
+        $this->resolver->setDefaults(array('one' => '1'));
+
+        $clone = clone $this->resolver;
+
+        // Changes after cloning don't affect each other
+        $this->resolver->setDefaults(array('two' => '2'));
+        $clone->setDefaults(array('three' => '3'));
+
+        $this->assertEquals(array(
+            'one' => '1',
+            'two' => '2',
+        ), $this->resolver->resolve());
+
+        $this->assertEquals(array(
+            'one' => '1',
+            'three' => '3',
+        ), $clone->resolve());
+    }
 }