@@ -16,6 +16,7 @@ class Twig_Environment

   protected $charset;

   protected $loader;

   protected $trimBlocks;

+  protected $strictMode;

   protected $debug;

   protected $autoReload;

   protected $cache;

@@ -56,6 +57,11 @@ class Twig_Environment

    *  * auto_reload: Whether to reload the template is the original source changed.

    *    If you don't provide the auto_reload option, it will be

    *    determined automatically base on the debug value.

+   *

+   *  * strict_mode: Whether to enable the strict mode or not. If enabled,

+   *    everything must be explicit. For instance, all variables must be

+   *    declared at the top of the template, you must pass explicitely the variables

+   *    when including another template, and so on. If not, a StrictError is thrown.

    */

   public function __construct(Twig_LoaderInterface $loader = null, $options = array())

   {

@@ -64,6 +70,7 @@ class Twig_Environment

       $this->setLoader($loader);

     }

+    $this->strictMode         = isset($options['strict_mode']) ? (bool) $options['strict_mode'] : false;

     $this->debug              = isset($options['debug']) ? (bool) $options['debug'] : false;

     $this->trimBlocks         = isset($options['trim_blocks']) ? (bool) $options['trim_blocks'] : false;

     $this->charset            = isset($options['charset']) ? $options['charset'] : 'UTF-8';

@@ -84,6 +91,21 @@ class Twig_Environment

     $this->baseTemplateClass = $class;

   }

+  public function enableStrictMode()

+  {

+    $this->strictMode = true;

+  }

+

+  public function disableStrictMode()

+  {

+    $this->strictMode = false;

+  }

+

+  public function isStrictMode()

+  {

+    return $this->strictMode;

+  }

+

   public function enableDebug()

   {

     $this->debug = true;

@@ -30,6 +30,7 @@ class Twig_Extension_Core extends Twig_Extension

       new Twig_TokenParser_Import(),

       new Twig_TokenParser_Set(),

       new Twig_TokenParser_Debug(),

+      new Twig_TokenParser_Use(),

     );

   }

@@ -40,7 +41,10 @@ class Twig_Extension_Core extends Twig_Extension

    */

   public function getNodeVisitors()

   {

-    return array(new Twig_NodeVisitor_Filter());

+    return array(

+      new Twig_NodeVisitor_Filter(),

+      new Twig_NodeVisitor_StrictMode()

+    );

   }

   /**

@@ -12,6 +12,7 @@

 class Twig_Node_Expression_Name extends Twig_Node_Expression

 {

   protected $name;

+  protected $declared = false;

   public function __construct($name, $lineno)

   {

@@ -26,11 +27,23 @@ class Twig_Node_Expression_Name extends Twig_Node_Expression

   public function compile($compiler)

   {

-    $compiler->raw(sprintf('(isset($context[\'%s\']) ? $context[\'%s\'] : null)', $this->name, $this->name));

+    if ($this->declared)

+    {

+      $compiler->raw(sprintf('$context[\'%s\']', $this->name));

+    }

+    else

+    {

+      $compiler->raw(sprintf('(isset($context[\'%s\']) ? $context[\'%s\'] : null)', $this->name, $this->name));

+    }

   }

   public function getName()

   {

     return $this->name;

   }

+

+  public function setDeclared()

+  {

+    $this->declared = true;

+  }

 }

@@ -84,26 +84,38 @@ class Twig_Token

   {

     switch ($type)

     {

-      case 0:

-        return 'TEXT_TYPE';

-      case -1:

-        return 'EOF_TYPE';

-      case 1:

-        return 'BLOCK_START_TYPE';

-      case 2:

-        return 'VAR_START_TYPE';

-      case 3:

-        return 'BLOCK_END_TYPE';

-      case 4:

-        return 'VAR_END_TYPE';

-      case 5:

-        return 'NAME_TYPE';

-      case 6:

-        return 'NUMBER_TYPE';

-      case 7:

-        return 'STRING_TYPE';

-      case 8:

-        return 'OPERATOR_TYPE';

+      case self::EOF_TYPE:

+        $name = 'EOF_TYPE';

+        break;

+      case self::TEXT_TYPE:

+        $name = 'TEXT_TYPE';

+        break;

+      case self::BLOCK_START_TYPE:

+        $name = 'BLOCK_START_TYPE';

+        break;

+      case self::VAR_START_TYPE:

+        $name = 'VAR_START_TYPE';

+        break;

+      case selg::BLOCK_END_TYPE:

+        $name = 'BLOCK_END_TYPE';

+        break;

+      case self::VAR_END_TYPE:

+        $name = 'VAR_END_TYPE';

+        break;

+      case self::NAME_TYPE:

+        $name = 'NAME_TYPE';

+        break;

+      case self::NUMBER_TYPE:

+        $name = 'NUMBER_TYPE';

+        break;

+      case self::STRING_TYPE:

+        $name = 'STRING_TYPE';

+        break;

+      case self::OPERATOR_TYPE:

+        $name = 'OPERATOR_TYPE';

+        break;

+      default:

+        throw new InvalidArgumentException(sprintf('Token of type %s does not exist.', $type));

     }

     return $short ? $name : 'Twig_Token::'.$name;