[12.x] Add Arr::mapKeys() method

Author: david-valdivia

src/Illuminate/Collections/Arr.php

@@ -793,6 +793,27 @@ public static function map(array $array, callable $callback)
         return array_combine($keys, $items);
     }
 
+    /**
+     * Map over an array's keys.
+     *
+     * @param  array  $array
+     * @param  callable  $callback
+     * @return array
+     */
+    public static function mapKeys(array $array, callable $callback): array
+    {
+        $keys = array_keys($array);
+        $values = array_values($array);
+
+        try {
+            $newKeys = array_map($callback, $keys, $values);
+        } catch (ArgumentCountError) {
+            $newKeys = array_map($callback, $keys);
+        }
+
+        return array_combine($newKeys, $values);
+    }
+
     /**
      * Run an associative map over each of the items.
      *

tests/Support/SupportArrTest.php

@@ -8,6 +8,7 @@
 use Illuminate\Support\Collection;
 use Illuminate\Support\ItemNotFoundException;
 use Illuminate\Support\MultipleItemsFoundException;
+use Illuminate\Support\Str;
 use InvalidArgumentException;
 use PHPUnit\Framework\Attributes\IgnoreDeprecations;
 use PHPUnit\Framework\TestCase;
@@ -993,6 +994,37 @@ public function testMap()
         $this->assertEquals(['first' => 'taylor', 'last' => 'otwell'], $data);
     }
 
+    public function testMapKeys()
+    {
+        // Basic transformation
+        $array = ['first_name' => 'Taylor', 'last_name' => 'Otwell'];
+        $result = Arr::mapKeys($array, fn($key) => Str::camel($key));
+        $this->assertEquals(['firstName' => 'Taylor', 'lastName' => 'Otwell'], $result);
+
+        // With value parameter
+        $array = ['name' => 'Taylor', 'age' => 31];
+        $result = Arr::mapKeys($array, fn($key, $value) => is_numeric($value) ? "num_{$key}" : $key);
+        $this->assertEquals(['name' => 'Taylor', 'num_age' => 31], $result);
+
+        // Key collision - last wins
+        $array = ['name' => 'First', 'NAME' => 'Second'];
+        $result = Arr::mapKeys($array, fn($key) => strtolower($key));
+        $this->assertEquals(['name' => 'Second'], $result);
+
+        // Empty array
+        $this->assertEquals([], Arr::mapKeys([], fn($key) => $key));
+
+        // Numeric keys
+        $array = [1, 2, 3];
+        $result = Arr::mapKeys($array, fn($key) => "item_{$key}");
+        $this->assertEquals(['item_0' => 1, 'item_1' => 2, 'item_2' => 3], $result);
+
+        // Prefix example
+        $config = ['host' => 'localhost', 'port' => 3306, 'database' => 'app'];
+        $result = Arr::mapKeys($config, fn($key) => "db_{$key}");
+        $this->assertEquals(['db_host' => 'localhost', 'db_port' => 3306, 'db_database' => 'app'], $result);
+    }
+
     public function testMapWithEmptyArray()
     {
         $mapped = Arr::map([], static function ($value, $key) {