Moving filter() into Set2.

lib/Cake/Test/Case/Utility/Set2Test.php

@@ -512,4 +512,33 @@ public function testContains() {
 		$this->assertFalse(Set2::contains($a, $b));
 	}
 
+/**
+ * testFilter method
+ *
+ * @return void
+ */
+	public function testFilter() {
+		$result = Set2::filter(array('0', false, true, 0, array('one thing', 'I can tell you', 'is you got to be', false)));
+		$expected = array('0', 2 => true, 3 => 0, 4 => array('one thing', 'I can tell you', 'is you got to be'));
+		$this->assertSame($expected, $result);
+
+		$result = Set2::filter(array(1, array(false)));
+		$expected = array(1);
+		$this->assertEquals($expected, $result);
+
+		$result = Set2::filter(array(1, array(false, false)));
+		$expected = array(1);
+		$this->assertEquals($expected, $result);
+
+		$result = Set2::filter(array(1, array('empty', false)));
+		$expected = array(1, array('empty'));
+		$this->assertEquals($expected, $result);
+
+		$result = Set2::filter(array(1, array('2', false, array(3, null))));
+		$expected = array(1, array('2', 2 => array(3)));
+		$this->assertEquals($expected, $result);
+
+		$this->assertSame(array(), Set2::filter(array()));
+	}
+
 }

lib/Cake/Utility/Set2.php

@@ -112,8 +112,33 @@ public static function check(array $data, $path) {
 
 	}
 
+/**
+ * Recursively filters empty elements out of a route array, excluding '0'.
+ *
+ * @param array $data Either an array to filter, or value when in callback
+ * @return array Filtered array
+ * @link http://book.cakephp.org/2.0/en/core-utility-libraries/set.html#Set::filter
+ */
 	public static function filter(array $data) {
-
+		foreach ($data as $k => $v) {
+			if (is_array($v)) {
+				$data[$k] = Set2::filter($v);
+			}
+		}
+		return array_filter($data, array('Set2', '_filter'));
+	}
+
+/**
+ * Callback function for filtering.
+ *
+ * @param array $var Array to filter.
+ * @return boolean
+ */
+	protected static function _filter($var) {
+		if ($var === 0 || $var === '0' || !empty($var)) {
+			return true;
+		}
+		return false;
 	}
 
 /**