feat: add underscore array class

Author: adhocore

src/UnderscoreArray.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace Ahc\Underscore;
+
+class UnderscoreArray extends UnderscoreBase
+{
+    public function first()
+    {
+        return \reset($this->data);
+    }
+
+    public function last()
+    {
+        return \end($this->data);
+    }
+
+    public function compact()
+    {
+        return new static(\array_filter($this->data));
+    }
+
+    public function flatten()
+    {
+        return new static($this->flat($this->data));
+    }
+
+    public function unique($fn = null)
+    {
+        if (null === $fn) {
+            return new static(\array_unique($this->data));
+        }
+
+        $ids = $data = [];
+        $fn  = $this->valueFn($fn);
+
+        foreach ($this->data as $index => $value) {
+            if (!isset($ids[$id = $fn($value, $index)])) {
+                $ids[$id] = true;
+
+                $data[$index] = $value;
+            }
+        }
+
+        return new static($data);
+    }
+
+    public function uniq($fn)
+    {
+        return $this->unique($fn);
+    }
+}