initial commit

app/Game/EntityList.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Game;
+
+final class EntityList extends \ArrayObject
+{
+    public function remove(GameObject $gameObject): void
+    {
+        foreach (array_keys($this->getArrayCopy()) as $key) {
+            if ($this[$key] === $gameObject) {
+                $this->offsetUnset($key);
+                break;
+            }
+        }
+    }
+
+    public function findByKind(string $kind): array
+    {
+        $found = [];
+        foreach ($this as $entity) {
+            if ($entity->kind() === $kind) {
+                $found[] = $entity;
+            }
+        }
+
+        return $found;
+    }
+
+    /** Snapshot copy so entities added mid-iteration are not touched. */
+    public function copy(): array
+    {
+        $copy = [];
+        foreach ($this as $entity) {
+            $copy[] = $entity;
+        }
+
+        return $copy;
+    }
+}