Flattening function for arrays

src/ArrayUtils.php

@@ -9,6 +9,8 @@
 
 namespace Zend\Stdlib;
 
+use RecursiveArrayIterator;
+use RecursiveIteratorIterator;
 use Traversable;
 use Zend\Stdlib\ArrayUtils\MergeRemoveKey;
 use Zend\Stdlib\ArrayUtils\MergeReplaceKeyInterface;
@@ -332,4 +334,17 @@ public static function filter(array $data, $callback, $flag = null)
 
         return $output;
     }
+
+    /**
+     * Flatten an array.
+     *
+     * Keys will be removed. Values will be kept in a single dimension array.
+     *
+     * @param array $data
+     * @return array
+     */
+    public static function flatten(array $data)
+    {
+        return iterator_to_array(new RecursiveIteratorIterator(new RecursiveArrayIterator($data), RecursiveIteratorIterator::LEAVES_ONLY), false);
+    }
 }

test/ArrayUtilsTest.php

@@ -527,6 +527,28 @@ function ($key) {
         ];
     }
 
+    public function flattenArrays()
+    {
+        return [
+            [
+                ['bar', 'buz'],
+                ['bar', 'buz']
+            ],
+            [
+                ['foo' => 'bar', 'fiz' => 'buz'],
+                ['bar', 'buz']
+            ],
+            [
+                ['foo' =>  ['bar', 'fiz' => 'buz']],
+                ['bar', 'buz']
+            ],
+            [
+                ['foo' =>  ['blah' => ['eh' => 'bar'], 'fiz' => 'buz']],
+                ['bar', 'buz']
+            ],
+        ];
+    }
+
     /**
      * @dataProvider filterArrays
      */
@@ -542,4 +564,13 @@ public function testInvalidCallableRaiseInvalidArgumentException()
     {
         ArrayUtils::filter([], "INVALID");
     }
+
+
+    /**
+     * @dataProvider flattenArrays
+     */
+    public function testFlattenArray($input, $expected)
+    {
+        $this->assertEquals($expected, ArrayUtils::flatten($input));
+    }
 }