--- /dev/null
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Serializer\Mapping\Factory;
+
+use Symfony\Component\Serializer\Exception\InvalidArgumentException;
+
+/**
+ * Resolves a class name.
+ *
+ * @internal
+ *
+ * @author Kévin Dunglas <dunglas@gmail.com>
+ */
+trait ClassResolverTrait
+{
+ /**
+ * Gets a class name for a given class or instance.
+ *
+ * @param mixed $value
+ *
+ * @return string
+ *
+ * @throws InvalidArgumentException If the class does not exists
+ */
+ private function getClass($value)
+ {
+ if (is_string($value)) {
+ if (!class_exists($value) && !interface_exists($value)) {
+ throw new InvalidArgumentException(sprintf('The class or interface "%s" does not exist.', $value));
+ }
+
+ return ltrim($value, '\\');
+ }
+
+ if (!is_object($value)) {
+ throw new InvalidArgumentException(sprintf('Cannot create metadata for non-objects. Got: "%s"', gettype($value)));
+ }
+
+ return get_class($value);
+ }
+}