[10.x] Add Arr::mapWithKeys() (#47000)

* Add `Arr::mapWithKeys()`

* Code style

* Code style

* Code style

src/Illuminate/Collections/Arr.php

@@ -563,6 +563,35 @@ public static function map(array $array, callable $callback)
         return array_combine($keys, $items);
     }
 
+    /**
+     * Run an associative map over each of the items.
+     *
+     * The callback should return an associative array with a single key/value pair.
+     *
+     * @template TKey
+     * @template TValue
+     * @template TMapWithKeysKey of array-key
+     * @template TMapWithKeysValue
+     *
+     * @param  array<TKey, TValue>  $array
+     * @param  callable(TValue, TKey): array<TMapWithKeysKey, TMapWithKeysValue>  $callback
+     * @return array
+     */
+    public static function mapWithKeys(array $array, callable $callback)
+    {
+        $result = [];
+
+        foreach ($array as $key => $value) {
+            $assoc = $callback($value, $key);
+
+            foreach ($assoc as $mapKey => $mapValue) {
+                $result[$mapKey] = $mapValue;
+            }
+        }
+
+        return $result;
+    }
+
     /**
      * Push an item onto the beginning of an array.
      *

src/Illuminate/Collections/Collection.php

@@ -816,17 +816,7 @@ public function mapToDictionary(callable $callback)
      */
     public function mapWithKeys(callable $callback)
     {
-        $result = [];
-
-        foreach ($this->items as $key => $value) {
-            $assoc = $callback($value, $key);
-
-            foreach ($assoc as $mapKey => $mapValue) {
-                $result[$mapKey] = $mapValue;
-            }
-        }
-
-        return new static($result);
+        return new static(Arr::mapWithKeys($this->items, $callback));
     }
 
     /**

tests/Support/SupportArrTest.php

@@ -642,6 +642,24 @@ public function testMap()
         $this->assertEquals(['first' => 'taylor', 'last' => 'otwell'], $data);
     }
 
+    public function testMapWithKeys()
+    {
+        $data = [
+            ['name' => 'Blastoise', 'type' => 'Water', 'idx' => 9],
+            ['name' => 'Charmander', 'type' => 'Fire', 'idx' => 4],
+            ['name' => 'Dragonair', 'type' => 'Dragon', 'idx' => 148],
+        ];
+
+        $data = Arr::mapWithKeys($data, function ($pokemon) {
+            return [$pokemon['name'] => $pokemon['type']];
+        });
+
+        $this->assertEquals(
+            ['Blastoise' => 'Water', 'Charmander' => 'Fire', 'Dragonair' => 'Dragon'],
+            $data
+        );
+    }
+
     public function testMapByReference()
     {
         $data = ['first' => 'taylor', 'last' => 'otwell'];