1 files changed, 51 insertions, 0 deletions
diff --git a/apps/dav/lib/Paginate/LimitedCopyIterator.php b/apps/dav/lib/Paginate/LimitedCopyIterator.php
new file mode 100644
index 00000000000..7f19885bc7d
--- /dev/null
+++ b/apps/dav/lib/Paginate/LimitedCopyIterator.php
@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\DAV\Paginate;
+
+/**
+ * Save a copy of the first X items into a separate iterator
+ *
+ * This allows us to pass the iterator to the cache while keeping a copy
+ * of the required items.
+ *
+ * @extends \AppendIterator<int, int, \Iterator<int, int>>
+ */
+class LimitedCopyIterator extends \AppendIterator {
+	private array $skipped = [];
+	private array $copy = [];
+
+	public function __construct(\Traversable $iterator, int $count, int $offset = 0) {
+		parent::__construct();
+
+		if (!$iterator instanceof \Iterator) {
+			$iterator = new \IteratorIterator($iterator);
+		}
+		$iterator = new \NoRewindIterator($iterator);
+
+		$i = 0;
+		while ($iterator->valid() && ++$i <= $offset) {
+			$this->skipped[] = $iterator->current();
+			$iterator->next();
+		}
+
+		while ($iterator->valid() && count($this->copy) < $count) {
+			$this->copy[] = $iterator->current();
+			$iterator->next();
+		}
+
+		$this->append(new \ArrayIterator($this->skipped));
+		$this->append($this->getRequestedItems());
+		$this->append($iterator);
+	}
+
+	public function getRequestedItems(): \Iterator {
+		return new \ArrayIterator($this->copy);
+	}
+}