--- /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\Config\Definition;
+
+/**
+ * Common Interface among all nodes.
+ *
+ * In most cases, it is better to inherit from BaseNode instead of implementing
+ * this interface yourself.
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+interface NodeInterface
+{
+ /**
+ * Returns the name of the node.
+ *
+ * @return string The name of the node
+ */
+ public function getName();
+
+ /**
+ * Returns the path of the node.
+ *
+ * @return string The node path
+ */
+ public function getPath();
+
+ /**
+ * Returns true when the node is required.
+ *
+ * @return bool If the node is required
+ */
+ public function isRequired();
+
+ /**
+ * Returns true when the node has a default value.
+ *
+ * @return bool If the node has a default value
+ */
+ public function hasDefaultValue();
+
+ /**
+ * Returns the default value of the node.
+ *
+ * @return mixed The default value
+ *
+ * @throws \RuntimeException if the node has no default value
+ */
+ public function getDefaultValue();
+
+ /**
+ * Normalizes the supplied value.
+ *
+ * @param mixed $value The value to normalize
+ *
+ * @return mixed The normalized value
+ */
+ public function normalize($value);
+
+ /**
+ * Merges two values together.
+ *
+ * @param mixed $leftSide
+ * @param mixed $rightSide
+ *
+ * @return mixed The merged values
+ */
+ public function merge($leftSide, $rightSide);
+
+ /**
+ * Finalizes a value.
+ *
+ * @param mixed $value The value to finalize
+ *
+ * @return mixed The finalized value
+ */
+ public function finalize($value);
+}