Add the Cycle operation.

spec/drupol/collection/CollectionSpec.php

@@ -316,6 +316,25 @@ public function it_can_count_its_items(): void
             ->shouldReturn(3);
     }
 
+    public function it_can_cycle(): void
+    {
+        $this
+            ->beConstructedThrough('with', [['1', '2', '3']]);
+
+        $this
+            ->cycle(1)
+            ->shouldIterateAs(['1', '2', '3']);
+
+        $this
+            ->cycle(2)
+            ->shouldIterateAs(['1', '2', '3', '1', '2', '3']);
+
+        $this
+            ->cycle()
+            ->limit(7)
+            ->shouldIterateAs(['1', '2', '3', '1', '2', '3', '1']);
+    }
+
     public function it_can_distinct(): void
     {
         $stdclass = new \stdClass();

src/Collection.php

@@ -11,6 +11,7 @@
 use drupol\collection\Operation\Chunk;
 use drupol\collection\Operation\Collapse;
 use drupol\collection\Operation\Combine;
+use drupol\collection\Operation\Cycle;
 use drupol\collection\Operation\Distinct;
 use drupol\collection\Operation\Explode;
 use drupol\collection\Operation\Filter;
@@ -123,6 +124,16 @@ public function count(): int
         return $this->transform(new Count());
     }
 
+    /**
+     * {@inheritdoc}
+     *
+     * @return \drupol\collection\Contract\Collection
+     */
+    public function cycle(int $count = 0): BaseInterface
+    {
+        return new Collection($this->run(new Cycle($count)));
+    }
+
     /**
      * {@inheritdoc}
      *

src/Contract/Collection.php

@@ -16,6 +16,7 @@ interface Collection extends
     Collapseable,
     Combineable,
     Containsable,
+    Cycleable,
     Distinctable,
     Explodeable,
     Filterable,

src/Contract/Cycleable.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace drupol\collection\Contract;
+
+/**
+ * Interface Cycleable.
+ */
+interface Cycleable
+{
+    /**
+     * @param int $count
+     *
+     * @return \drupol\collection\Contract\Collection
+     */
+    public function cycle(int $count = 0): Base;
+}

src/Operation/Cycle.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace drupol\collection\Operation;
+
+use drupol\collection\Contract\Operation;
+
+/**
+ * Class Cycle.
+ */
+final class Cycle implements Operation
+{
+    /**
+     * @var int
+     */
+    private $count;
+
+    /**
+     * Cycle constructor.
+     *
+     * @param int $count
+     */
+    public function __construct(int $count = 0)
+    {
+        $this->count = $count;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function on(iterable $collection): \Closure
+    {
+        $count = $this->count;
+
+        return static function () use ($collection, $count) {
+            for ($j = 0 === $count ? 1 : 0; $j !== $count; ++$j) {
+                foreach ($collection as $value) {
+                    yield $value;
+                }
+            }
+        };
+    }
+}