Add traversable test

doc/tests/traversable.rst

@@ -0,0 +1,11 @@
+``traversable``
+=========
+
+``traversable`` checks if a variable is an array or a traversable object:
+
+.. code-block:: jinja
+
+    {# evaluates to true if the foo variable is traversable #}
+    {% if foo is traversable %}
+        ...
+    {% endif %}

lib/Twig/Extension/Core.php

@@ -203,6 +203,7 @@ class Twig_Extension_Core extends Twig_Extension
             'constant'    => new Twig_Test_Node('Twig_Node_Expression_Test_Constant'),
             'empty'       => new Twig_Test_Function('twig_test_empty'),
             'array'       => new Twig_Test_Function('is_array'),
+            'traversable' => new Twig_Test_Function('twig_test_traversable'),
         );
     }
 
@@ -1014,3 +1015,22 @@ function twig_test_empty($value)
 
     return false === $value || (empty($value) && '0' != $value);
 }
+
+/**
+ * Checks if a variable is traversable.
+ *
+ * <pre>
+ * {# evaluates to true if the foo variable is an array or a traversable object #}
+ * {% if foo is traversable %}
+ *     {# ... #}
+ * {% endif %}
+ * </pre>
+ *
+ * @param mixed $value A variable
+ *
+ * @return Boolean true if the value is traversable
+ */
+function twig_test_traversable($value)
+{
+    return is_array($value) || (is_object($value) && $value instanceof Traversable);
+}

test/Twig/Tests/Fixtures/tests/traversable.test

@@ -0,0 +1,19 @@
+--TEST--
+"traversable" test
+--TEMPLATE--
+{{ foo is traversable ? 'ok' : 'ko' }}
+{{ traversable is traversable ? 'ok' : 'ko' }}
+{{ obj is traversable ? 'ok' : 'ko' }}
+{{ val is traversable ? 'ok' : 'ko' }}
+--DATA--
+return array(
+    'foo' => array(),
+    'traversable' => new ArrayIterator(array()),
+    'obj' => new stdClass(),
+    'val' => 'test',
+);
+--EXPECT--
+ok
+ok
+ko
+ko