1 files changed, 118 insertions, 0 deletions
diff --git a/editor/libeditor/ManualNAC.h b/editor/libeditor/ManualNAC.h
new file mode 100644
index 0000000000..17d0e4d273
--- /dev/null
+++ b/editor/libeditor/ManualNAC.h
@@ -0,0 +1,118 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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_ManualNAC_h
+#define mozilla_ManualNAC_h
+
+#include "mozilla/dom/Element.h"
+#include "mozilla/RefPtr.h"
+
+namespace mozilla {
+
+// 16 seems to be the maximum number of manual Native Anonymous Content (NAC)
+// nodes that editor creates for a given element.
+//
+// These need to be manually removed by the machinery that sets the NAC,
+// otherwise we'll leak.
+using ManualNACArray = AutoTArray<RefPtr<dom::Element>, 16>;
+
+/**
+ * Smart pointer class to own "manual" Native Anonymous Content, and perform
+ * the necessary registration and deregistration on the parent element.
+ */
+class ManualNACPtr final {
+ public:
+  ManualNACPtr() = default;
+  MOZ_IMPLICIT ManualNACPtr(decltype(nullptr)) {}
+  explicit ManualNACPtr(already_AddRefed<dom::Element> aNewNAC)
+      : mPtr(aNewNAC) {
+    if (!mPtr) {
+      return;
+    }
+
+    // Record the NAC on the element, so that AllChildrenIterator can find it.
+    nsIContent* parentContent = mPtr->GetParent();
+    auto nac = static_cast<ManualNACArray*>(
+        parentContent->GetProperty(nsGkAtoms::manualNACProperty));
+    if (!nac) {
+      nac = new ManualNACArray();
+      parentContent->SetProperty(nsGkAtoms::manualNACProperty, nac,
+                                 nsINode::DeleteProperty<ManualNACArray>);
+    }
+    nac->AppendElement(mPtr);
+  }
+
+  // We use move semantics, and delete the copy-constructor and operator=.
+  ManualNACPtr(ManualNACPtr&& aOther) : mPtr(std::move(aOther.mPtr)) {}
+  ManualNACPtr(ManualNACPtr& aOther) = delete;
+  ManualNACPtr& operator=(ManualNACPtr&& aOther) {
+    mPtr = std::move(aOther.mPtr);
+    return *this;
+  }
+  ManualNACPtr& operator=(ManualNACPtr& aOther) = delete;
+
+  ~ManualNACPtr() { Reset(); }
+
+  void Reset() {
+    if (!mPtr) {
+      return;
+    }
+
+    RefPtr<dom::Element> ptr = std::move(mPtr);
+    RemoveContentFromNACArray(ptr);
+  }
+
+  static bool IsManualNAC(nsIContent* aAnonContent) {
+    MOZ_ASSERT(aAnonContent->IsRootOfNativeAnonymousSubtree());
+    MOZ_ASSERT(aAnonContent->IsInComposedDoc());
+
+    auto* nac = static_cast<ManualNACArray*>(
+        aAnonContent->GetParent()->GetProperty(nsGkAtoms::manualNACProperty));
+    return nac && nac->Contains(aAnonContent);
+  }
+
+  static void RemoveContentFromNACArray(nsIContent* aAnonymousContent) {
+    nsIContent* parentContent = aAnonymousContent->GetParent();
+    if (!parentContent) {
+      NS_WARNING("Potentially leaking manual NAC");
+      return;
+    }
+
+    // Remove reference from the parent element.
+    auto* nac = static_cast<ManualNACArray*>(
+        parentContent->GetProperty(nsGkAtoms::manualNACProperty));
+    // Document::AdoptNode might remove all properties before destroying editor.
+    // So we have to consider that NAC could be already removed.
+    if (nac) {
+      nac->RemoveElement(aAnonymousContent);
+      if (nac->IsEmpty()) {
+        parentContent->RemoveProperty(nsGkAtoms::manualNACProperty);
+      }
+    }
+
+    aAnonymousContent->UnbindFromTree();
+  }
+
+  dom::Element* get() const { return mPtr.get(); }
+  dom::Element* operator->() const { return get(); }
+  operator dom::Element*() const& { return get(); }
+
+ private:
+  RefPtr<dom::Element> mPtr;
+};
+
+}  // namespace mozilla
+
+inline void ImplCycleCollectionUnlink(mozilla::ManualNACPtr& field) {
+  field.Reset();
+}
+
+inline void ImplCycleCollectionTraverse(
+    nsCycleCollectionTraversalCallback& callback,
+    const mozilla::ManualNACPtr& field, const char* name, uint32_t flags = 0) {
+  CycleCollectionNoteChild(callback, field.get(), name, flags);
+}
+
+#endif  // #ifndef mozilla_ManualNAC_h