feature: add new chunk() and keys() methods

README.md

@@ -479,3 +479,20 @@ $joined = $collection->implode(', ', function (User $user): string {
     return $user->name();
 });
 ```
+
+### Chunk
+The `chunk()` method will take your collection and return it split into
+chunks (max size of `$limit`) and by default will preserve the keys
+```php
+$collection = new Collection(['a', 'b', 'c', 'd', 'e']);
+$chunks = $collection->chunk(2);
+// $chunks is now: new Collection([[0 => 'a', 1 => 'b'], [2 => 'c', 3 => 'd'], [4 => 'e']]);
+```
+
+### Keys
+The `keys()` method will take your collection and return the keys of each
+of the items within it
+```php
+$collection = new Collection(['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5]);
+$keys = $collection->keys(); // ['a', 'b', 'c', 'd', 'e']
+```

src/Collection.php

@@ -433,6 +433,28 @@ public function implode($glue = '', callable $callable = null): string
         return implode($glue, $array);
     }
 
+    /**
+     * Chunks a collection into a new collection where each item contains max `$limit` number of items from the original
+     *
+     * @param int $limit
+     * @param bool $preserveKeys
+     * @return Collection
+     */
+    public function chunk(int $limit, bool $preserveKeys = true): self
+    {
+        return new Collection(array_chunk($this->getArrayCopy(), $limit, $preserveKeys));
+    }
+
+    /**
+     * Returns the keys of the collection
+     *
+     * @return array
+     */
+    public function keys(): array
+    {
+        return array_keys($this->getArrayCopy());
+    }
+
     /**
      * Get a New Instance of the Same Type
      *

tests/CollectionTest.php

@@ -753,6 +753,28 @@ public function foo(): string {
         );
     }
 
+    /** @test */
+    public function itChunksTheCollection(): void
+    {
+        $collection = new Collection(['a', 'b', 'c', 'd', 'e']);
+        $chunks = $collection->chunk(2);
+
+        $expectedChunks = new Collection([[0 => 'a', 1 => 'b'], [2 => 'c', 3 => 'd'], [4 => 'e']]);
+
+        $this->assertEquals($expectedChunks, $chunks);
+    }
+
+    /** @test */
+    public function itReturnsTheArrayKeysOfTheCollection(): void
+    {
+        $collection = new Collection(['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5]);
+        $keys = $collection->keys();
+
+        $expectedKeys = ['a', 'b', 'c', 'd', 'e'];
+
+        $this->assertEquals($expectedKeys, $keys);
+    }
+