Add InsertValueBeforeKey

src/Modifier/InsertValueBeforeKey.php

@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Yiisoft\Arrays\Modifier;
+
+/**
+ * Inserts given value before specified key while performing {@see ArrayHelper::merge()}.
+ *
+ * The modifier should be specified as
+ *
+ * ```php
+ * 'some-key' => new InsertValueBeforeKey('some-value', 'a-key-to-insert-before'),
+ * ```
+ *
+ * ```php
+ * $a = [
+ *     'name' => 'Yii',
+ *     'version' => '1.0',
+ * ];
+ *
+ * $b = [
+ *    'version' => '1.1',
+ *    'options' => [],
+ *    'vendor' => new InsertValueBeforeKey('Yiisoft', 'name'),
+ * ];
+ *
+ * $result = ArrayHelper::merge($a, $b);
+ * ```
+ *
+ * Will result in:
+ *
+ * ```php
+ * [
+ *     'vendor' => 'Yiisoft',
+ *     'name' => 'Yii',
+ *     'version' => '1.1',
+ *     'options' => [],
+ * ];
+ */
+final class InsertValueBeforeKey implements ModifierInterface
+{
+    /** @var mixed value of any type */
+    private $value;
+
+    private string $key;
+
+    public function __construct($value, string $key)
+    {
+        $this->value = $value;
+        $this->key = $key;
+    }
+
+    public function apply(array $data, $key): array
+    {
+        $res = [];
+        foreach ($data as $k => $v) {
+            if ($k === $this->key) {
+                $res[$key] = $this->value;
+            }
+            $res[$k] = $v;
+        }
+
+        return $res;
+    }
+}

tests/ArrayMergeTest.php

@@ -6,6 +6,7 @@
 
 use PHPUnit\Framework\TestCase;
 use Yiisoft\Arrays\ArrayHelper;
+use Yiisoft\Arrays\Modifier\InsertValueBeforeKey;
 use Yiisoft\Arrays\Modifier\RemoveKeys;
 use Yiisoft\Arrays\Modifier\ReplaceValue;
 use Yiisoft\Arrays\Modifier\ReverseBlockMerge;
@@ -245,7 +246,6 @@ public function testMergeWithNullValues(): void
         $this->assertEquals($expected, $result);
     }
 
-
     public function testMergeIntegerKeyedArraysWithSameValue(): void
     {
         $a = ['2019-01-25'];
@@ -257,4 +257,27 @@ public function testMergeIntegerKeyedArraysWithSameValue(): void
 
         $this->assertEquals($expected, $result);
     }
+
+    public function testMergeWithInsertValueBeforekey(): void
+    {
+        $a = [
+            'name' => 'Yii',
+            'version' => '1.0',
+        ];
+        $b = [
+            'version' => '1.1',
+            'options' => [],
+            'vendor' => new InsertValueBeforeKey('Yiisoft', 'name'),
+        ];
+
+        $result = ArrayHelper::merge($a, $b);
+        $expected = [
+            'vendor' => 'Yiisoft',
+            'name' => 'Yii',
+            'version' => '1.1',
+            'options' => [],
+        ];
+
+        $this->assertSame($expected, $result);
+    }
 }