Add Pack operation.

docs/pages/api.rst

@@ -153,7 +153,6 @@ Signature: ``Collection::with($data = [], ...$parameters);``
     // With a resource/stream
     $collection = Collection::with(fopen( __DIR__ . '/vendor/autoload.php', 'r'));
 
-
 Methods (operations)
 --------------------
 
@@ -832,6 +831,29 @@ Signature: ``Collection::only(...$keys);``
     $collection = Collection::with(range(10, 100))
         ->only(3, 10, 'a', 9);
 
+pack
+~~~~
+
+Wrap each items into an array containing 2 items: the key and the value.
+
+Interface: `Packable`_
+
+Signature: ``Collection::pack();``
+
+.. code-block:: php
+
+    $input = ['a' => 'b', 'c' => 'd', 'e' => 'f'];
+
+    $c = Collection::fromIterable($input)
+        ->pack();
+
+     // [
+     //   ['a', 'b'],
+     //   ['c', 'd'],
+     //   ['e', 'f'],
+     // ]
+
+
 pad
 ~~~
 

spec/loophp/collection/CollectionSpec.php

@@ -1312,6 +1312,30 @@ public function it_can_nullsy(): void
             ->shouldReturn(false);
     }
 
+    public function it_can_pack(): void
+    {
+        $input = array_combine(range('a', 'c'), range('a', 'c'));
+
+        $this::fromIterable($input)
+            ->pack()
+            ->shouldIterateAs(
+                [
+                    0 => [
+                        0 => 'a',
+                        1 => 'a',
+                    ],
+                    1 => [
+                        0 => 'b',
+                        1 => 'b',
+                    ],
+                    2 => [
+                        0 => 'c',
+                        1 => 'c',
+                    ],
+                ]
+            );
+    }
+
     public function it_can_pad(): void
     {
         $input = array_combine(range('A', 'E'), range('A', 'E'));

src/Collection.php

@@ -49,6 +49,7 @@
 use loophp\collection\Operation\Normalize;
 use loophp\collection\Operation\Nth;
 use loophp\collection\Operation\Only;
+use loophp\collection\Operation\Pack;
 use loophp\collection\Operation\Pad;
 use loophp\collection\Operation\Pair;
 use loophp\collection\Operation\Permutate;
@@ -512,6 +513,11 @@ public function only(...$keys): CollectionInterface
         return $this->run(new Only(...$keys));
     }
 
+    public function pack(): CollectionInterface
+    {
+        return $this->run(new Pack());
+    }
+
     public function pad(int $size, $value): CollectionInterface
     {
         return $this->run(new Pad($size, $value));

src/Contract/Operation/Packable.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Contract\Operation;
+
+use loophp\collection\Contract\Collection;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+interface Packable
+{
+    /**
+     * @psalm-return \loophp\collection\Contract\Collection<int, array{0: TKey, 1: T}>
+     */
+    public function pack(): Collection;
+}

src/Operation/Pack.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace loophp\collection\Operation;
+
+use Closure;
+use Generator;
+use Iterator;
+use loophp\collection\Contract\Operation;
+
+/**
+ * @psalm-template TKey
+ * @psalm-template TKey of array-key
+ * @psalm-template T
+ */
+final class Pack extends AbstractOperation implements Operation
+{
+    public function __invoke(): Closure
+    {
+        return
+            /**
+             * @psalm-param Iterator<TKey, T> $iterator
+             *
+             * @psalm-return Generator<int, array{0:TKey, 1:T}>
+             */
+            static function (Iterator $iterator): Generator {
+                foreach ($iterator as $key => $value) {
+                    yield [$key, $value];
+                }
+            };
+    }
+}