diff --git a/src/Symfony/Component/DependencyInjection/Configuration/ArrayNode.php b/src/Symfony/Component/DependencyInjection/Configuration/ArrayNode.php
new file mode 100644
index 000000000000..936c16fcac21
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/ArrayNode.php
@@ -0,0 +1,105 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration;
+
+use Symfony\Component\DependencyInjection\Extension\Extension;
+
+class ArrayNode extends BaseNode implements PrototypeNodeInterface
+{
+    protected $normalizeTransformations;
+    protected $children;
+    protected $prototype;
+    protected $keyAttribute;
+
+    public function __construct($name, NodeInterface $parent = null, array $beforeTransformations = array(), array $afterTransformations = array(), array $normalizeTransformations = array(), $keyAttribute = null)
+    {
+        parent::__construct($name, $parent, $beforeTransformations, $afterTransformations);
+
+        $this->children = array();
+        $this->normalizeTransformations = $normalizeTransformations;
+        $this->keyAttribute = $keyAttribute;
+    }
+
+    public function setName($name)
+    {
+        $this->name = $name;
+    }
+
+    public function setPrototype(PrototypeNodeInterface $node)
+    {
+        if (count($this->children) > 0) {
+            throw new \RuntimeException('An ARRAY node must either have concrete children, or a prototype node.');
+        }
+
+        $this->prototype = $node;
+    }
+
+    public function addChild(NodeInterface $node)
+    {
+        $name = $node->getName();
+        if (empty($name)) {
+            throw new \InvalidArgumentException('Node name cannot be empty.');
+        }
+        if (isset($this->children[$name])) {
+            throw new \InvalidArgumentException(sprintf('The node "%s" already exists.', $name));
+        }
+        if (null !== $this->prototype) {
+            throw new \RuntimeException('An ARRAY node must either have a prototype, or concrete children.');
+        }
+
+        $this->children[$name] = $node;
+    }
+
+    protected function validateType($value)
+    {
+        if (!is_array($value)) {
+            throw new InvalidTypeException(sprintf(
+                'Invalid type for path "%s". Expected array, but got %s',
+                $this->getPath(),
+                json_encode($value)
+            ));
+        }
+    }
+
+    protected function normalizeValue($value)
+    {
+        foreach ($this->normalizeTransformations as $transformation) {
+            list($singular, $plural) = $transformation;
+
+            if (!isset($value[$singular])) {
+                continue;
+            }
+
+            $value[$plural] = Extension::normalizeConfig($value, $singular, $plural);
+        }
+
+        if (null !== $this->prototype) {
+            $normalized = array();
+            foreach ($value as $k => $v) {
+                if (null !== $this->keyAttribute && is_array($v) && isset($v[$this->keyAttribute])) {
+                    $k = $v[$this->keyAttribute];
+                }
+
+                $this->prototype->setName($k);
+                if (null !== $this->keyAttribute) {
+                    $normalized[$k] = $this->prototype->normalize($v);
+                } else {
+                    $normalized[] = $this->prototype->normalize($v);
+                }
+            }
+
+            return $normalized;
+        }
+
+        $normalized = array();
+        foreach ($this->children as $name => $child) {
+            if (!array_key_exists($name, $value)) {
+                continue;
+            }
+
+            $normalized[$name] = $child->normalize($value[$name]);
+        }
+
+        return $normalized;
+    }
+}
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Configuration/BaseNode.php b/src/Symfony/Component/DependencyInjection/Configuration/BaseNode.php
new file mode 100644
index 000000000000..69f5847fbcd7
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/BaseNode.php
@@ -0,0 +1,64 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration;
+
+abstract class BaseNode implements NodeInterface
+{
+    protected $name;
+    protected $parent;
+    protected $beforeTransformations;
+    protected $afterTransformations;
+    protected $nodeFactory;
+
+    public function __construct($name, NodeInterface $parent = null, $beforeTransformations = array(), $afterTransformations = array())
+    {
+        if (false !== strpos($name, '.')) {
+            throw new \InvalidArgumentException('The name must not contain ".".');
+        }
+
+        $this->name = $name;
+        $this->parent = $parent;
+        $this->beforeTransformations = $beforeTransformations;
+        $this->afterTransformations = $afterTransformations;
+    }
+
+    public function getName()
+    {
+        return $this->name;
+    }
+
+    public function getPath()
+    {
+        $path = $this->name;
+
+        if (null !== $this->parent) {
+            $path = $this->parent->getPath().'.'.$path;
+        }
+
+        return $path;
+    }
+
+    public final function normalize($value)
+    {
+        // run before transformations
+        foreach ($this->beforeTransformations as $transformation) {
+            $value = $transformation($value);
+        }
+
+        // validate type
+        $this->validateType($value);
+
+        // normalize value
+        $value = $this->normalizeValue($value);
+
+        // run after transformations
+        foreach ($this->afterTransformations as $transformation) {
+            $value = $transformation($value);
+        }
+
+        return $value;
+    }
+
+    abstract protected function validateType($value);
+    abstract protected function normalizeValue($value);
+}
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Configuration/Builder/ExprBuilder.php b/src/Symfony/Component/DependencyInjection/Configuration/Builder/ExprBuilder.php
new file mode 100644
index 000000000000..c8f2e0cbdd84
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/Builder/ExprBuilder.php
@@ -0,0 +1,62 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration\Builder;
+
+class ExprBuilder
+{
+    public $parent;
+    public $ifPart;
+    public $thenPart;
+
+    public function __construct($parent)
+    {
+        $this->parent = $parent;
+    }
+
+    public function ifTrue(\Closure $closure)
+    {
+        $this->ifPart = $closure;
+
+        return $this;
+    }
+
+    public function ifString()
+    {
+        $this->ifPart = function($v) { return is_string($v); };
+
+        return $this;
+    }
+
+    public function ifNull()
+    {
+        $this->ifPart = function($v) { return null === $v; };
+
+        return $this;
+    }
+
+    public function ifArray()
+    {
+        $this->ifPart = function($v) { return is_array($v); };
+
+        return $this;
+    }
+
+    public function then(\Closure $closure)
+    {
+        $this->thenPart = $closure;
+
+        return $this;
+    }
+
+    public function end()
+    {
+        if (null === $this->ifPart) {
+            throw new \RuntimeException('You must specify an if part.');
+        }
+        if (null === $this->thenPart) {
+            throw new \RuntimeException('You must specify a then part.');
+        }
+
+        return $this->parent;
+    }
+}
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Configuration/Builder/NodeBuilder.php b/src/Symfony/Component/DependencyInjection/Configuration/Builder/NodeBuilder.php
new file mode 100644
index 000000000000..0c63068d7143
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/Builder/NodeBuilder.php
@@ -0,0 +1,92 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration\Builder;
+
+class NodeBuilder
+{
+    /************
+     * READ-ONLY
+     ************/
+    public $name;
+    public $type;
+    public $key;
+    public $parent;
+    public $children;
+    public $prototype;
+    public $normalizeTransformations;
+    public $beforeTransformations;
+    public $afterTransformations;
+
+    public function __construct($name, $type, $parent = null)
+    {
+        $this->name = $name;
+        $this->type = $type;
+        $this->parent = $parent;
+
+        $this->children =
+        $this->beforeTransformations =
+        $this->afterTransformations =
+        $this->normalizeTransformations = array();
+    }
+
+    /****************************
+     * FLUID INTERFACE
+     ****************************/
+
+    public function node($name, $type)
+    {
+        $node = new NodeBuilder($name, $type, $this);
+
+        return $this->children[$name] = $node;
+    }
+
+    public function normalize($key, $plural = null)
+    {
+        if (null === $plural) {
+            $plural = $key.'s';
+        }
+
+        $this->normalizeTransformations[] = array($key, $plural);
+
+        return $this;
+    }
+
+    public function key($name)
+    {
+        $this->key = $name;
+
+        return $this;
+    }
+
+    public function before(\Closure $closure = null)
+    {
+        if (null !== $closure) {
+            $this->beforeTransformations[] = $closure;
+
+            return $this;
+        }
+
+        return $this->beforeTransformations[] = new ExprBuilder($this);
+    }
+
+    public function prototype($type)
+    {
+        return $this->prototype = new NodeBuilder(null, $type, $this);
+    }
+
+    public function after(\Closure $closure = null)
+    {
+        if (null !== $closure) {
+            $this->afterTransformations[] = $closure;
+
+            return $this;
+        }
+
+        return $this->afterTransformations[] = new ExprBuilder($this);
+    }
+
+    public function end()
+    {
+        return $this->parent;
+    }
+}
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Configuration/Builder/TreeBuilder.php b/src/Symfony/Component/DependencyInjection/Configuration/Builder/TreeBuilder.php
new file mode 100644
index 000000000000..93f48bdf1936
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/Builder/TreeBuilder.php
@@ -0,0 +1,90 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration\Builder;
+
+use Symfony\Component\DependencyInjection\Configuration\ArrayNode;
+use Symfony\Component\DependencyInjection\Configuration\ScalarNode;
+
+class TreeBuilder
+{
+    protected $root;
+    protected $tree;
+
+    public function root($name, $type)
+    {
+        $this->tree = null;
+
+        return $this->root = new NodeBuilder($name, $type, $this);
+    }
+
+    public function buildTree()
+    {
+        if (null === $this->root) {
+            throw new \RuntimeException('You haven\'t added a root node.');
+        }
+        if (null !== $this->tree) {
+            return $this->tree;
+        }
+        $this->root->parent = null;
+
+        return $this->tree = $this->createConfigNode($this->root);
+    }
+
+    protected function createConfigNode(NodeBuilder $node)
+    {
+        $node->beforeTransformations = $this->buildExpressions($node->beforeTransformations);
+        $node->afterTransformations = $this->buildExpressions($node->afterTransformations);
+
+        $method = 'create'.$node->type.'ConfigNode';
+        if (!method_exists($this, $method)) {
+            throw new \RuntimeException(sprintf('Unknown node type: "%s"', $node->type));
+        }
+
+        return $this->$method($node);
+    }
+
+    protected function createScalarConfigNode(NodeBuilder $node)
+    {
+        return new ScalarNode($node->name, $node->parent, $node->beforeTransformations, $node->afterTransformations);
+    }
+
+    protected function createArrayConfigNode(NodeBuilder $node)
+    {
+        $configNode = new ArrayNode($node->name, $node->parent, $node->beforeTransformations, $node->afterTransformations, $node->normalizeTransformations, $node->key);
+
+        foreach ($node->children as $child) {
+            $child->parent = $configNode;
+
+            $configNode->addChild($this->createConfigNode($child));
+        }
+
+        if (null !== $node->prototype) {
+            $node->prototype->parent = $configNode;
+            $configNode->setPrototype($this->createConfigNode($node->prototype));
+        }
+
+        return $configNode;
+    }
+
+    protected function buildExpressions(array $expressions)
+    {
+        foreach ($expressions as $k => $expr) {
+            if (!$expr instanceof ExprBuilder) {
+                continue;
+            }
+
+            $expressions[$k] = function($v) use($expr) {
+                $ifPart = $expr->ifPart;
+                if (true !== $ifPart($v)) {
+                    return $v;
+                }
+
+                $thenPart = $expr->thenPart;
+
+                return $thenPart($v);
+            };
+        }
+
+        return $expressions;
+    }
+}
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Configuration/Exception/Exception.php b/src/Symfony/Component/DependencyInjection/Configuration/Exception/Exception.php
new file mode 100644
index 000000000000..e5a464b27694
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/Exception/Exception.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration\Exception;
+
+class Exception extends \RuntimeException
+{
+}
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Configuration/Exception/InvalidTypeException.php b/src/Symfony/Component/DependencyInjection/Configuration/Exception/InvalidTypeException.php
new file mode 100644
index 000000000000..436c80fa80ad
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/Exception/InvalidTypeException.php
@@ -0,0 +1,12 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration\Exception;
+
+/**
+ * This exception is thrown if an invalid type is encountered.
+ *
+ * @author johannes
+ */
+class InvalidTypeException extends Exception
+{
+}
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Configuration/NodeInterface.php b/src/Symfony/Component/DependencyInjection/Configuration/NodeInterface.php
new file mode 100644
index 000000000000..a5e8611c637d
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/NodeInterface.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration;
+
+interface NodeInterface
+{
+    function getName();
+    function getPath();
+    function normalize($value);
+}
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Configuration/PrototypeNodeInterface.php b/src/Symfony/Component/DependencyInjection/Configuration/PrototypeNodeInterface.php
new file mode 100644
index 000000000000..eccb24f4ff96
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/PrototypeNodeInterface.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration;
+
+/**
+ * This interface must be implemented by nodes which can be used as prototypes.
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+interface PrototypeNodeInterface extends NodeInterface
+{
+    function setName($name);
+}
\ No newline at end of file
diff --git a/src/Symfony/Component/DependencyInjection/Configuration/ScalarNode.php b/src/Symfony/Component/DependencyInjection/Configuration/ScalarNode.php
new file mode 100644
index 000000000000..cdcebe3dac6a
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Configuration/ScalarNode.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Configuration;
+
+use Symfony\Component\DependencyInjection\Configuration\Exception\InvalidTypeException;
+
+class ScalarNode extends BaseNode implements PrototypeNodeInterface
+{
+    public function setName($name)
+    {
+        $this->name = $name;
+    }
+
+    protected function validateType($value)
+    {
+        if (!is_scalar($value)) {
+            throw new \InvalidTypeException(sprintf(
+                'Invalid type for path "%s". Expected scalar, but got %s.',
+                $this->getPath(),
+                json_encode($value)
+            ));
+        }
+    }
+
+    protected function normalizeValue($value)
+    {
+        return $value;
+    }
+}
\ No newline at end of file
diff --git a/tests/Symfony/Tests/Component/DependencyInjection/Configuration/NormalizationTest.php b/tests/Symfony/Tests/Component/DependencyInjection/Configuration/NormalizationTest.php
new file mode 100644
index 000000000000..4afbdb9eeeb8
--- /dev/null
+++ b/tests/Symfony/Tests/Component/DependencyInjection/Configuration/NormalizationTest.php
@@ -0,0 +1,127 @@
+<?php
+
+namespace Symfony\Tests\Component\DependencyInjection\Configuration;
+
+use Symfony\Component\DependencyInjection\Configuration\NodeInterface;
+use Symfony\Component\DependencyInjection\Configuration\Builder\TreeBuilder;
+
+class NormalizerTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @dataProvider getEncoderTests
+     */
+    public function testNormalizeEncoders($denormalized)
+    {
+        $tb = new TreeBuilder();
+        $tree = $tb
+            ->root('root_name', 'array')
+                ->normalize('encoder')
+                ->node('encoders', 'array')
+                    ->key('class')
+                    ->prototype('array')
+                        ->before()->ifString()->then(function($v) { return array('algorithm' => $v); })->end()
+                        ->node('algorithm', 'scalar')->end()
+                    ->end()
+                ->end()
+            ->end()
+            ->buildTree()
+        ;
+
+        $normalized = array(
+            'encoders' => array(
+                'foo' => array('algorithm' => 'plaintext'),
+            ),
+        );
+
+        $this->assertNormalized($tree, $denormalized, $normalized);
+    }
+
+    public function getEncoderTests()
+    {
+        $configs = array();
+
+        // XML
+        $configs[] = array(
+            'encoder' => array(
+                array('class' => 'foo', 'algorithm' => 'plaintext'),
+            ),
+        );
+
+        // XML when only one element of this type
+        $configs[] = array(
+            'encoder' => array('class' => 'foo', 'algorithm' => 'plaintext'),
+        );
+
+        // YAML/PHP
+        $configs[] = array(
+            'encoders' => array(
+                array('class' => 'foo', 'algorithm' => 'plaintext'),
+            ),
+        );
+
+        // YAML/PHP
+        $configs[] = array(
+            'encoders' => array(
+                'foo' => 'plaintext',
+            ),
+        );
+
+        // YAML/PHP
+        $configs[] = array(
+            'encoders' => array(
+                'foo' => array('algorithm' => 'plaintext'),
+            ),
+        );
+
+        return array_map(function($v) {
+            return array($v);
+        }, $configs);
+    }
+
+    /**
+     * @dataProvider getAnonymousKeysTests
+     */
+    public function testAnonymousKeysArray($denormalized)
+    {
+        $tb = new TreeBuilder();
+        $tree = $tb
+            ->root('root', 'array')
+                ->node('logout', 'array')
+                    ->normalize('handler')
+                    ->node('handlers', 'array')
+                        ->prototype('scalar')->end()
+                    ->end()
+                ->end()
+            ->end()
+            ->buildTree()
+        ;
+
+        $normalized = array('logout' => array('handlers' => array('a', 'b', 'c')));
+
+        $this->assertNormalized($tree, $denormalized, $normalized);
+    }
+
+    public function getAnonymousKeysTests()
+    {
+        $configs = array();
+
+        $configs[] = array(
+            'logout' => array(
+                'handlers' => array('a', 'b', 'c'),
+            ),
+        );
+
+        $configs[] = array(
+            'logout' => array(
+                'handler' => array('a', 'b', 'c'),
+            ),
+        );
+
+        return array_map(function($v) { return array($v); }, $configs);
+    }
+
+    public static function assertNormalized(NodeInterface $tree, $denormalized, $normalized)
+    {
+        self::assertSame($normalized, $tree->normalize($denormalized));
+    }
+}
\ No newline at end of file