New Diff and DiffKeys operation.

spec/loophp/collection/CollectionSpec.php

@@ -568,6 +568,30 @@ public function it_can_cycle(): void
             ->shouldIterateAs($generator());
     }
 
+    public function it_can_diff(): void
+    {
+        $this::fromIterable(range(1, 5))
+            ->diff(1, 2, 3, 9)
+            ->shouldIterateAs([3 => 4, 4 => 5]);
+
+        $this::fromIterable(range(1, 5))
+            ->diff()
+            ->shouldIterateAs(range(1, 5));
+    }
+
+    public function it_can_diffKeys(): void
+    {
+        $input = array_combine(range('a', 'e'), range(1, 5));
+
+        $this::fromIterable($input)
+            ->diffKeys('b', 'd')
+            ->shouldIterateAs(['a' => 1, 'c' => 3, 'e' => 5]);
+
+        $this::fromIterable($input)
+            ->diffKeys()
+            ->shouldIterateAs($input);
+    }
+
     public function it_can_distinct(): void
     {
         $stdclass = new stdClass();

src/Collection.php

@@ -21,6 +21,8 @@
 use loophp\collection\Operation\Combine;
 use loophp\collection\Operation\Compact;
 use loophp\collection\Operation\Cycle;
+use loophp\collection\Operation\Diff;
+use loophp\collection\Operation\DiffKeys;
 use loophp\collection\Operation\Distinct;
 use loophp\collection\Operation\Explode;
 use loophp\collection\Operation\Filter;
@@ -149,6 +151,16 @@ public function cycle(?int $length = null): BaseInterface
         return $this->run(new Cycle($length));
     }
 
+    public function diff(...$values): BaseInterface
+    {
+        return $this->run(new Diff(...$values));
+    }
+
+    public function diffKeys(...$values): BaseInterface
+    {
+        return $this->run(new DiffKeys(...$values));
+    }
+
     public function distinct(): BaseInterface
     {
         return $this->run(new Distinct());

src/Contract/Collection.php

@@ -15,6 +15,8 @@
 use loophp\collection\Contract\Operation\Combineable;
 use loophp\collection\Contract\Operation\Compactable;
 use loophp\collection\Contract\Operation\Cycleable;
+use loophp\collection\Contract\Operation\Diffable;
+use loophp\collection\Contract\Operation\Diffkeysable;
 use loophp\collection\Contract\Operation\Distinctable;
 use loophp\collection\Contract\Operation\Explodeable;
 use loophp\collection\Contract\Operation\Filterable;
@@ -86,6 +88,8 @@ interface Collection extends
     Compactable,
     Containsable,
     Cycleable,
+    Diffable,
+    Diffkeysable,
     Distinctable,
     Explodeable,
     Falsyable,

src/Contract/Operation/Diffable.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Contract\Operation;
+
+use loophp\collection\Contract\Base;
+
+interface Diffable
+{
+    /**
+     * @param mixed ...$values
+     *
+     * @return \loophp\collection\Base|\loophp\collection\Contract\Collection
+     */
+    public function diff(...$values): Base;
+}

src/Contract/Operation/Diffkeysable.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Contract\Operation;
+
+use loophp\collection\Contract\Base;
+
+interface Diffkeysable
+{
+    /**
+     * @param mixed ...$values
+     *
+     * @return \loophp\collection\Base|\loophp\collection\Contract\Collection
+     */
+    public function diffKeys(...$values): Base;
+}

src/Operation/Diff.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use loophp\collection\Contract\Operation;
+
+use function in_array;
+
+final class Diff extends AbstractOperation implements Operation
+{
+    /**
+     * @param mixed ...$values
+     */
+    public function __construct(...$values)
+    {
+        $this->storage['values'] = $values;
+    }
+
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @param array<int, mixed> $values
+             */
+            static function (iterable $collection, $values): Generator {
+                foreach ($collection as $key => $value) {
+                    if (false === in_array($value, $values, true)) {
+                        yield $key => $value;
+                    }
+                }
+            };
+    }
+}

src/Operation/DiffKeys.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use loophp\collection\Contract\Operation;
+
+use function in_array;
+
+final class DiffKeys extends AbstractOperation implements Operation
+{
+    /**
+     * @param mixed ...$values
+     */
+    public function __construct(...$values)
+    {
+        $this->storage['values'] = $values;
+    }
+
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @param array<int, mixed> $values
+             */
+            static function (iterable $collection, $values): Generator {
+                foreach ($collection as $key => $value) {
+                    if (false === in_array($key, $values, true)) {
+                        yield $key => $value;
+                    }
+                }
+            };
+    }
+}