Added: Countable interface support for empty test

lib/Twig/Extension/Core.php

@@ -426,7 +426,7 @@ function twig_reverse_filter($array)
 
 /**
  * Sorts an array.
- * 
+ *
  * @param array $array An array
  */
 function twig_sort_filter($array)
@@ -706,7 +706,7 @@ function twig_ensure_traversable($seq)
  * <pre>
  * {% if foo.attribute is sameas(false) %}
  *    the foo attribute really is the ``false`` PHP value
- * {% endif %} 
+ * {% endif %}
  * </pre>
  *
  * @param mixed $value A PHP variable
@@ -839,5 +839,8 @@ function twig_test_defined($name, $context)
  */
 function twig_test_empty($value)
 {
+    if ($value instanceof Countable) {
+        return 0 == count($value);
+    }
     return false === $value || (empty($value) && '0' != $value);
 }

test/Twig/Tests/Fixtures/tests/empty.test

@@ -7,12 +7,31 @@
 {{ array is empty ? 'ok' : 'ko' }}
 {{ zero is empty ? 'ok' : 'ko' }}
 {{ string is empty ? 'ok' : 'ko' }}
+{{ countable_empty is empty ? 'ok' : 'ko' }}
+{{ countable_not_empty is empty ? 'ok' : 'ko' }}
 --DATA--
-return array('foo' => '', 'bar' => null, 'foobar' => false, 'array' => array(), 'zero' => 0, 'string' => '0');
+
+class CountableStub implements Countable
+{
+    private $items;
+
+    public function __construct(array $items)
+    {
+        $this->items = $items;
+    }
+
+    public function count()
+    {
+        return count($this->items);
+    }
+}
+return array('foo' => '', 'bar' => null, 'foobar' => false, 'array' => array(), 'zero' => 0, 'string' => '0', 'countable_empty' => new CountableStub(array()), 'countable_not_empty' => new CountableStub(array(1, 2)));
 --EXPECT--
 ok
 ok
 ok
 ok
 ko
+ko
+ok
 ko