tor-browser

The Tor Browser
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ConnectedAncestorTracker.h (2598B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #ifndef mozilla_ConnectedAncestorTracker_h
      8 #define mozilla_ConnectedAncestorTracker_h
      9 
     10 #include "mozilla/Attributes.h"
     11 #include "mozilla/PresShell.h"
     12 #include "mozilla/dom/Document.h"
     13 #include "mozilla/dom/Element.h"
     14 #include "nsIContent.h"
     15 
     16 namespace mozilla {
     17 
     18 /**
     19 * AutoConnectedAncestorTracker is a struct which keeps referring the connected
     20 * and closest ancestor of a content node.  E.g., say, there are nodes are:
     21 * Document -> <html> -> <body> -> <div> and starts tracking it with the <div>,
     22 * and the <body> is removed, this refers the <html> with mConnectedAncestor.
     23 * Note that even after reconnected the <body>, this won't refer the <div> as
     24 * connected one.
     25 */
     26 struct MOZ_STACK_CLASS AutoConnectedAncestorTracker final {
     27  explicit AutoConnectedAncestorTracker(nsIContent& aContent)
     28      : mContent(aContent),
     29        mPresShell(aContent.IsInComposedDoc()
     30                       ? aContent.OwnerDoc()->GetPresShell()
     31                       : nullptr) {
     32    if (mPresShell) {
     33      mPresShell->AddConnectedAncestorTracker(*this);
     34    }
     35  }
     36  ~AutoConnectedAncestorTracker() {
     37    if (mPresShell) {
     38      mPresShell->RemoveConnectedAncestorTracker(*this);
     39    }
     40  }
     41 
     42  [[nodiscard]] bool ContentWasRemoved() const {
     43    return mPresShell && mConnectedAncestor;
     44  }
     45  [[nodiscard]] dom::Element* GetConnectedElement() const {
     46    return ContentWasRemoved()
     47               ? mConnectedAncestor->GetAsElementOrParentElement()
     48               : mContent->GetAsElementOrParentElement();
     49  }
     50  [[nodiscard]] nsIContent* GetConnectedContent() const {
     51    return ContentWasRemoved() ? nsIContent::FromNode(mConnectedAncestor)
     52                               : mContent.get();
     53  }
     54  [[nodiscard]] nsINode& ConnectedNode() const {
     55    return ContentWasRemoved() ? *mConnectedAncestor : mContent.ref();
     56  }
     57 
     58  // Store the original content node.
     59  const OwningNonNull<nsIContent> mContent;
     60  // Store the connected ancestor node if and only if mContent has been deleted
     61  // from the document.
     62  nsCOMPtr<nsINode> mConnectedAncestor;
     63 
     64  // The PresShell which manages this instance.
     65  const RefPtr<PresShell> mPresShell;
     66 
     67  AutoConnectedAncestorTracker* mPreviousTracker = nullptr;
     68 };
     69 
     70 }  // namespace mozilla
     71 
     72 #endif  // #ifndef mozilla_ConnectedAncestorTracker_h