Add RandomIterator Iterator.

spec/loophp/collection/Iterator/RandomIteratorSpec.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace spec\loophp\collection\Iterator;
+
+use ArrayIterator;
+use loophp\collection\Iterator\RandomIterator;
+use PhpSpec\ObjectBehavior;
+
+class RandomIteratorSpec extends ObjectBehavior
+{
+    public function it_can_get_the_innerIterator()
+    {
+        $this->getInnerIterator()->shouldBeAnInstanceOf(ArrayIterator::class);
+    }
+
+    public function it_is_initializable()
+    {
+        $this->shouldHaveType(RandomIterator::class);
+    }
+
+    public function let()
+    {
+        $iterator = new ArrayIterator(range(0, 4));
+
+        $this->beConstructedWith($iterator);
+    }
+}

src/Iterator/RandomIterator.php

@@ -0,0 +1,107 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Iterator;
+
+use ArrayIterator;
+use Iterator;
+use OuterIterator;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T of string
+ *
+ * @implements Iterator<TKey, T>
+ */
+final class RandomIterator implements Iterator, OuterIterator
+{
+    /**
+     * @var array<int, int>
+     */
+    private $indexes;
+
+    /**
+     * @var Iterator
+     * @psalm-var Iterator<TKey, T>
+     */
+    private $inner;
+
+    /**
+     * @var ArrayIterator
+     * @psalm-var ArrayIterator<int, array{0: TKey, 1: T}>
+     */
+    private $iterator;
+
+    /**
+     * @var int
+     */
+    private $key;
+
+    /**
+     * @psalm-param Iterator<TKey, T> $iterator
+     */
+    public function __construct(Iterator $iterator)
+    {
+        $this->inner = $iterator;
+        $this->iterator = $this->buildArrayIterator($iterator);
+        $this->indexes = array_keys($this->iterator->getArrayCopy());
+        $this->key = array_rand($this->indexes);
+    }
+
+    public function current()
+    {
+        $value = $this->iterator[$this->key];
+
+        return $value[1];
+    }
+
+    public function getInnerIterator()
+    {
+        return $this->inner;
+    }
+
+    public function key()
+    {
+        $value = $this->iterator[$this->key];
+
+        return $value[0];
+    }
+
+    public function next(): void
+    {
+        unset($this->indexes[$this->key]);
+
+        if ($this->valid()) {
+            $this->key = array_rand($this->indexes);
+        }
+    }
+
+    public function rewind()
+    {
+        $this->iterator->rewind();
+    }
+
+    public function valid(): bool
+    {
+        return [] !== $this->indexes;
+    }
+
+    /**
+     * @psalm-param Iterator<TKey, T> $iterator
+     *
+     * @psalm-return ArrayIterator<int, array{0: TKey, 1: T}>
+     */
+    private function buildArrayIterator(Iterator $iterator): ArrayIterator
+    {
+        /** @psalm-var ArrayIterator<int, array{0: TKey, 1: T}> $arrayIterator */
+        $arrayIterator = new ArrayIterator();
+
+        foreach ($iterator as $key => $value) {
+            $arrayIterator->append([$key, $value]);
+        }
+
+        return $arrayIterator;
+    }
+}

src/Operation/Shuffle.php

@@ -7,6 +7,7 @@
 use Closure;
 use Generator;
 use Iterator;
+use loophp\collection\Iterator\RandomIterator;
 
 /**
  * @psalm-template TKey
@@ -24,17 +25,7 @@ public function __invoke(): Closure
              * @psalm-return Generator<TKey, T, mixed, void>
              */
             static function (Iterator $iterator): Generator {
-                /** @psalm-var Iterator<int, array{0: TKey, 1: T}> $pack */
-                $pack = Pack::of()($iterator);
-                $data = iterator_to_array($pack);
-
-                while ([] !== $data) {
-                    $randomKey = array_rand($data);
-
-                    yield $data[$randomKey][0] => $data[$randomKey][1];
-
-                    unset($data[$randomKey]);
-                }
+                return yield from new RandomIterator($iterator);
             };
     }
 }