1 files changed, 63 insertions, 0 deletions
diff --git a/layout/base/DepthOrderedFrameList.cpp b/layout/base/DepthOrderedFrameList.cpp
new file mode 100644
index 0000000000..3c9826d954
--- /dev/null
+++ b/layout/base/DepthOrderedFrameList.cpp
@@ -0,0 +1,63 @@
+/* -*- 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/. */
+
+#include "DepthOrderedFrameList.h"
+#include "nsIFrame.h"
+#include "nsContainerFrame.h"
+
+namespace mozilla {
+
+void DepthOrderedFrameList::Add(nsIFrame* aFrame) {
+  // Is this root already scheduled for reflow?
+  // FIXME: This could possibly be changed to a uniqueness assertion, with some
+  // work in ResizeReflowIgnoreOverride (and maybe others?)
+  // FIXME(emilio): Should probably reuse the traversal for insertion.
+  if (Contains(aFrame)) {
+    // We don't expect frame to change depths.
+    MOZ_ASSERT(aFrame->GetDepthInFrameTree() ==
+               mList[mList.IndexOf(aFrame)].mDepth);
+    return;
+  }
+
+  mList.InsertElementSorted(
+      FrameAndDepth{aFrame, aFrame->GetDepthInFrameTree()},
+      FrameAndDepth::CompareByReverseDepth{});
+}
+
+void DepthOrderedFrameList::Remove(nsIFrame* aFrame) {
+  mList.RemoveElement(aFrame);
+}
+
+nsIFrame* DepthOrderedFrameList::PopShallowestRoot() {
+  // List is sorted in order of decreasing depth, so there are no shallower
+  // frames than the last one.
+  const FrameAndDepth& lastFAD = mList.PopLastElement();
+  nsIFrame* frame = lastFAD.mFrame;
+  // We don't expect frame to change depths.
+  MOZ_ASSERT(frame->GetDepthInFrameTree() == lastFAD.mDepth);
+  return frame;
+}
+
+bool DepthOrderedFrameList::FrameIsAncestorOfAnyElement(
+    nsIFrame* aFrame) const {
+  MOZ_ASSERT(aFrame);
+
+  // Look for a path from any element to aFrame, following GetParent(). This
+  // check mirrors what FrameNeedsReflow() would have done if the reflow root
+  // didn't get in the way.
+  for (nsIFrame* f : mList) {
+    do {
+      if (f == aFrame) {
+        return true;
+      }
+      f = f->GetParent();
+    } while (f);
+  }
+
+  return false;
+}
+
+}  // namespace mozilla