added ArrayHelper::flatten()

ArrayHelper.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace fphammerle\helpers;
+
+class ArrayHelper
+{
+    /**
+     * @return array
+     */
+    public static function flatten(array $arr)
+    {
+        return iterator_to_array(
+            new \RecursiveIteratorIterator(new \RecursiveArrayIterator($arr)),
+            false
+            );
+    }
+}

tests/ArrayHelperTest.php

@@ -0,0 +1,94 @@
+<?php
+
+namespace fphammerle\helpers\tests;
+
+use fphammerle\helpers\ArrayHelper;
+
+class ArrayHelperTest extends \PHPUnit_Framework_TestCase
+{
+    public function testFlattenEmpty()
+    {
+        $this->assertEquals(
+            [],
+            ArrayHelper::flatten([])
+            );
+    }
+
+    public function testFlattenFlat()
+    {
+        $this->assertEquals(
+            [1, 2, 3],
+            ArrayHelper::flatten([1, 2, 3])
+            );
+    }
+
+    public function testFlatten2D()
+    {
+        $this->assertEquals(
+            [1, 2, 3, 4, 5],
+            ArrayHelper::flatten([1, [2, 3], [4], 5])
+            );
+    }
+
+    public function testFlatten2DEmpty()
+    {
+        $this->assertEquals(
+            [1, 2, 3, 4, 5],
+            ArrayHelper::flatten([[], 1, [2, 3], [], [4], 5])
+            );
+    }
+
+    public function testFlatten3D()
+    {
+        $this->assertEquals(
+            [1, 2, 3, 4, 5, 6],
+            ArrayHelper::flatten([1, [[2, 3], 4], [[5], [6]]])
+            );
+    }
+
+    public function testFlatten3DEmpty()
+    {
+        $this->assertEquals(
+            [1, 2, 3, 4, 5, 6],
+            ArrayHelper::flatten([1, [[2, [], 3], 4, []], [[5], [6]], []])
+            );
+    }
+
+    public function testFlattenAssociativeLetterFlat()
+    {
+        $this->assertEquals(
+            [1, 2, 3, 4],
+            ArrayHelper::flatten(['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4])
+            );
+    }
+
+    public function testFlattenAssociativeDigit()
+    {
+        $this->assertEquals(
+            [1, 2, 3, 4],
+            ArrayHelper::flatten([1 => 1, 2 => 2, 3 => 3, 4 => 4])
+            );
+    }
+
+    public function testFlattenAssociativeDigitReverse()
+    {
+        $this->assertEquals(
+            [1, 2, 3, 4],
+            ArrayHelper::flatten([3 => 1, 2 => 2, 1 => 3, 0 => 4])
+            );
+    }
+
+    public function testFlattenMixed2D()
+    {
+        $this->assertEquals(
+            [1, 2, 3, 4, 5, 6, 7, 8],
+            ArrayHelper::flatten([
+                'a' => 1,
+                'b' => [2, 3],
+                'c' => ['#' => 4, '@' => 5],
+                'd' => [6, '$' => 7],
+                8,
+                ])
+            );
+    }
+}

tests/autoload.php

@@ -3,5 +3,6 @@
 // report all possible php errors
 error_reporting(-1);
 
+require_once(__DIR__ . '/../ArrayHelper.php');
 require_once(__DIR__ . '/../DateTimeHelper.php');
 require_once(__DIR__ . '/../StringHelper.php');