Fix various compatibility issues with PHP 8

libs/ical/PropertyBag.php

@@ -0,0 +1,74 @@
+<?php
+
+/*
+ * This file is part of the eluceo/iCal package.
+ *
+ * (c) Markus Poerschke <markus@eluceo.de>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Eluceo\iCal;
+
+class PropertyBag implements \IteratorAggregate
+{
+    /**
+     * @var array
+     */
+    protected $elements = [];
+
+    /**
+     * Creates a new Property with $name, $value and $params.
+     *
+     * @param       $name
+     * @param       $value
+     * @param array $params
+     *
+     * @return $this
+     */
+    public function set($name, $value, $params = [])
+    {
+        $this->add(new Property($name, $value, $params));
+
+        return $this;
+    }
+
+    /**
+     * @return Property|null
+     */
+    public function get(string $name)
+    {
+        if (isset($this->elements[$name])) {
+            return $this->elements[$name];
+        }
+
+        return null;
+    }
+
+    /**
+     * Adds a Property. If Property already exists an Exception will be thrown.
+     *
+     * @return $this
+     *
+     * @throws \Exception
+     */
+    public function add(Property $property)
+    {
+        $name = $property->getName();
+
+        if (isset($this->elements[$name])) {
+            throw new \Exception("Property with name '{$name}' already exists");
+        }
+
+        $this->elements[$name] = $property;
+
+        return $this;
+    }
+
+    #[\ReturnTypeWillChange]
+    public function getIterator()
+    {
+        return new \ArrayObject($this->elements);
+    }
+}