1 files changed, 41 insertions, 0 deletions
diff --git a/dom/base/TreeOrderedArray.h b/dom/base/TreeOrderedArray.h
new file mode 100644
index 0000000000..59f99f4e6e
--- /dev/null
+++ b/dom/base/TreeOrderedArray.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TreeOrderedArray_h
+#define mozilla_dom_TreeOrderedArray_h
+
+#include "nsTArray.h"
+
+namespace mozilla::dom {
+
+// A sorted tree-ordered list of raw pointers to nodes.
+template <typename Node>
+class TreeOrderedArray {
+ public:
+  operator const nsTArray<Node*>&() const { return mList; }
+
+  const nsTArray<Node*>* operator->() const { return &mList; }
+
+  // Inserts a node into the list, and returns the new index in the array.
+  //
+  // All the nodes in the list should be in the same subtree, and debug builds
+  // assert this.
+  //
+  // It's also forbidden to call Insert() with the same node multiple times, and
+  // it will assert as well.
+  inline size_t Insert(Node&);
+
+  bool RemoveElement(Node& aNode) { return mList.RemoveElement(&aNode); }
+
+  void Clear() { mList.Clear(); }
+
+ private:
+  AutoTArray<Node*, 1> mList;
+};
+
+}  // namespace mozilla::dom
+
+#endif