widget/nsAutoRollup.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "mozilla/widget/nsAutoRollup.h"
   7
   8 namespace mozilla {
   9 namespace widget {
  10
  11 /*static*/
  12 uint32_t nsAutoRollup::sCount = 0;
  13 /*static*/
  14 StaticRefPtr<nsIContent> nsAutoRollup::sLastRollup;
  15
  16 nsAutoRollup::nsAutoRollup() {
  17   // remember if sLastRollup was null, and only clear it upon destruction
  18   // if so. This prevents recursive usage of nsAutoRollup from clearing
  19   // sLastRollup when it shouldn't.
  20   mWasClear = !sLastRollup;
  21   sCount++;
  22 }
  23
  24 nsAutoRollup::nsAutoRollup(nsIContent* aRollup) {
  25   MOZ_ASSERT(!sLastRollup);
  26   mWasClear = true;
  27   sCount++;
  28   SetLastRollup(aRollup);
  29 }
  30
  31 nsAutoRollup::~nsAutoRollup() {
  32   if (sLastRollup && mWasClear) {
  33     sLastRollup = nullptr;
  34   }
  35   sCount--;
  36 }
  37
  38 /*static*/
  39 void nsAutoRollup::SetLastRollup(nsIContent* aLastRollup) {
  40   // There must be at least one nsAutoRollup on the stack.
  41   MOZ_ASSERT(sCount);
  42
  43   sLastRollup = aLastRollup;
  44 }
  45
  46 /*static*/
  47 nsIContent* nsAutoRollup::GetLastRollup() { return sLastRollup.get(); }
  48
  49 }  // namespace widget
  50 }  // namespace mozilla