feat: add support for filtering using key

src/IterableObject.php

@@ -16,6 +16,8 @@
 use function array_map;
 use function iterator_to_array;
 
+use const ARRAY_FILTER_USE_BOTH;
+
 /**
  * @internal
  *
@@ -40,7 +42,7 @@ public function __construct(iterable $iterable, bool $preserveKeys = true)
     }
 
     /**
-     * @param (callable(TValue):bool)|null $filter
+     * @param (callable(TValue):bool)|(callable(TValue,TKey):bool)|null $filter
      *
      * @return self<TKey, TValue>
      */
@@ -56,7 +58,9 @@ static function ($value): bool {
             return new self(new CallbackFilterIterator(new IteratorIterator($this->iterable), $filter));
         }
 
-        $filtered = $filter === null ? array_filter($this->iterable) : array_filter($this->iterable, $filter);
+        $filtered = $filter === null
+            ? array_filter($this->iterable)
+            : array_filter($this->iterable, $filter, ARRAY_FILTER_USE_BOTH);
 
         return new self($filtered);
     }

src/iterable-functions.php

@@ -87,7 +87,7 @@ function iterable_to_traversable(iterable $iterable): Traversable
 /**
  * Filters an iterable.
  *
- * @param (callable(TValue):bool)|null $filter
+ * @param (callable(TValue):bool)|(callable(TValue,TKey):bool)|null $filter
  *
  * @psalm-param iterable<TKey, TValue> $iterable
  * @psalm-return iterable<TKey, TValue>

tests/IterableFilterTest.php

@@ -4,6 +4,7 @@
 
 namespace BenTools\IterableFunctions\Tests;
 
+use Generator;
 use SplFixedArray;
 use Traversable;
 
@@ -47,3 +48,28 @@ static function ($input): bool {
     assert($filtered instanceof Traversable);
     assertSame([1 => 'bar'], iterator_to_array($filtered));
 });
+
+it('filters a Traversable object with a callback using key', function (): void {
+    $iterable = (function (): Generator {
+        yield 'foo' => 1;
+        yield 'bar' => 1;
+    })();
+    $filter =
+    static function (int $input, string $key): bool {
+        return $key === 'bar';
+    };
+    $filtered = iterable_filter($iterable, $filter);
+    assert($filtered instanceof Traversable);
+    assertSame(['bar' => 1], iterator_to_array($filtered));
+});
+
+it('filters an array with a callback using key', function (): void {
+    $iterable = ['foo' => 1, 'bar' => 1];
+    $filter =
+    static function (int $input, string $key): bool {
+        return $key === 'bar';
+    };
+    $filtered = iterable_filter($iterable, $filter);
+    assert($filtered instanceof Traversable);
+    assertSame(['bar' => 1], iterator_to_array($filtered));
+});