layout/style/ServoStyleSet.cpp
author Nika Layzell <nika@thelayzells.com>
Tue, 25 Sep 2018 17:34:53 +0200
changeset 507828 5e6dae0c1e5a4939ccd406f14607f7fafffd45a7
parent 507497 9ec6a81e695aef5d519d0e8a79927a9d6e915c03
child 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1448426 - Wrap windows.h to avoid problematic define statements, r=froydnj,glandium By default, windows.h exposes a large number of problematic define statements which are UpperCamelCase, such as a define from `CreateWindow` to `CreateWindow{A,W}`. As many of these names are generic (e.g. CreateFile, CreateWindow), they can mess up Gecko code that may legitimately have its own methods with the same names. The header also defines some traditional SCREAMING_SNAKE_CASE defines which can mess up our code by conflicting with local values. This patch adds a simple code generator which generates wrappers for these defines, and uses them to wrap the windows.h wrapper using the `stl_wrappers` mechanism, allowing us to use windows.h in more places. Differential Revision: https://phabricator.services.mozilla.com/D10932

/* -*- 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 "mozilla/ServoStyleSet.h"
#include "mozilla/ServoStyleSetInlines.h"

#include "gfxPlatformFontList.h"
#include "mozilla/AutoRestyleTimelineMarker.h"
#include "mozilla/DocumentStyleRootIterator.h"
#include "mozilla/EffectCompositor.h"
#include "mozilla/IntegerRange.h"
#include "mozilla/LookAndFeel.h"
#include "mozilla/ServoBindings.h"
#include "mozilla/RestyleManager.h"
#include "mozilla/ServoStyleRuleMap.h"
#include "mozilla/ServoTypes.h"
#include "mozilla/StyleAnimationValue.h"
#include "mozilla/css/Loader.h"
#include "mozilla/dom/AnonymousContent.h"
#include "mozilla/dom/ChildIterator.h"
#include "mozilla/dom/FontFaceSet.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/ElementInlines.h"
#include "nsCSSAnonBoxes.h"
#include "nsCSSFrameConstructor.h"
#include "nsCSSPseudoElements.h"
#include "nsDeviceContext.h"
#include "nsHTMLStyleSheet.h"
#include "nsIAnonymousContentCreator.h"
#include "nsIDocumentInlines.h"
#include "nsMediaFeatures.h"
#include "nsPrintfCString.h"
#include "nsSMILAnimationController.h"
#include "nsXBLPrototypeBinding.h"
#include "gfxUserFontSet.h"
#include "nsBindingManager.h"
#include "nsWindowSizes.h"
#include "GeckoProfiler.h"

using namespace mozilla;
using namespace mozilla::dom;

#ifdef DEBUG
bool
ServoStyleSet::IsCurrentThreadInServoTraversal()
{
  return sInServoTraversal && (NS_IsMainThread() || Servo_IsWorkerThread());
}
#endif

namespace mozilla {
ServoStyleSet* sInServoTraversal = nullptr;


// On construction, sets sInServoTraversal to the given ServoStyleSet.
// On destruction, clears sInServoTraversal and calls RunPostTraversalTasks.
class MOZ_RAII AutoSetInServoTraversal
{
public:
  explicit AutoSetInServoTraversal(ServoStyleSet* aSet)
    : mSet(aSet)
  {
    MOZ_ASSERT(!sInServoTraversal);
    MOZ_ASSERT(aSet);
    sInServoTraversal = aSet;
  }

  ~AutoSetInServoTraversal()
  {
    MOZ_ASSERT(sInServoTraversal);
    sInServoTraversal = nullptr;
    mSet->RunPostTraversalTasks();
  }

private:
  ServoStyleSet* mSet;
};

// Sets up for one or more calls to Servo_TraverseSubtree.
class MOZ_RAII AutoPrepareTraversal
{
public:
  explicit AutoPrepareTraversal(ServoStyleSet* aSet)
    // For markers for animations, we have already set the markers in
    // RestyleManager::PostRestyleEventForAnimations so that we don't need
    // to care about animation restyles here.
    : mTimelineMarker(aSet->mDocument->GetDocShell(), false)
    , mSetInServoTraversal(aSet)
  {
    MOZ_ASSERT(!aSet->StylistNeedsUpdate());
  }

private:
  AutoRestyleTimelineMarker mTimelineMarker;
  AutoSetInServoTraversal mSetInServoTraversal;
};

} // namespace mozilla

ServoStyleSet::ServoStyleSet()
  : mDocument(nullptr)
  , mAuthorStyleDisabled(false)
  , mStylistState(StylistState::NotDirty)
  , mUserFontSetUpdateGeneration(0)
  , mNeedsRestyleAfterEnsureUniqueInner(false)
{
}

ServoStyleSet::~ServoStyleSet()
{
  for (auto& sheetArray : mSheets) {
    for (auto& sheet : sheetArray) {
      sheet->DropStyleSet(this);
    }
  }
}

nsPresContext*
ServoStyleSet::GetPresContext()
{
  if (!mDocument) {
    return nullptr;
  }

  return mDocument->GetPresContext();
}

void
ServoStyleSet::Init(nsPresContext* aPresContext)
{
  mDocument = aPresContext->Document();
  MOZ_ASSERT(GetPresContext() == aPresContext);

  mRawSet.reset(Servo_StyleSet_Init(aPresContext));

  aPresContext->DeviceContext()->InitFontCache();

  // Now that we have an mRawSet, go ahead and notify about whatever stylesheets
  // we have so far.
  for (auto& sheetArray : mSheets) {
    for (auto& sheet : sheetArray) {
      // There's no guarantee this will create a list on the servo side whose
      // ordering matches the list that would have been created had all those
      // sheets been appended/prepended/etc after we had mRawSet. That's okay
      // because Servo only needs to maintain relative ordering within a sheet
      // type, which this preserves.

      MOZ_ASSERT(sheet->RawContents(),
                 "We should only append non-null raw sheets.");
      Servo_StyleSet_AppendStyleSheet(mRawSet.get(), sheet);
    }
  }

  // We added prefilled stylesheets into mRawSet, so the stylist is dirty.
  // The Stylist should be updated later when necessary.
  SetStylistStyleSheetsDirty();

  // We may have Shadow DOM style changes that we weren't notified about because
  // the document didn't have a shell, if the ShadowRoot was created in a
  // display: none iframe.
  //
  // Now that we got a shell, we may need to get them up-to-date.
  //
  // TODO(emilio, bug 1418159): This wouldn't be needed if the StyleSet was
  // owned by the document.
  SetStylistXBLStyleSheetsDirty();
}

template<typename Functor>
void
EnumerateShadowRoots(const nsIDocument& aDoc, const Functor& aCb)
{
  const nsIDocument::ShadowRootSet& shadowRoots = aDoc.ComposedShadowRoots();
  for (auto iter = shadowRoots.ConstIter(); !iter.Done(); iter.Next()) {
    ShadowRoot* root = iter.Get()->GetKey();
    MOZ_ASSERT(root);
    MOZ_DIAGNOSTIC_ASSERT(root->IsInComposedDoc());
    aCb(*root);
  }
}

void
ServoStyleSet::Shutdown()
{
  // Make sure we drop our cached styles before the presshell arena starts going
  // away.
  ClearNonInheritingComputedStyles();
  mRawSet = nullptr;
  mStyleRuleMap = nullptr;
}

void
ServoStyleSet::RecordShadowStyleChange(ShadowRoot& aShadowRoot)
{
  // TODO(emilio): We could keep track of the actual shadow roots that need
  // their styles recomputed.
  SetStylistXBLStyleSheetsDirty();

  // FIXME(emilio): This should be done using stylesheet invalidation instead.
  if (nsPresContext* pc = GetPresContext()) {
    pc->RestyleManager()->PostRestyleEvent(
      aShadowRoot.Host(), eRestyle_Subtree, nsChangeHint(0));
  }
}

void
ServoStyleSet::InvalidateStyleForDocumentStateChanges(EventStates aStatesChanged)
{
  MOZ_ASSERT(mDocument);
  MOZ_ASSERT(!aStatesChanged.IsEmpty());

  nsPresContext* pc = GetPresContext();
  if (!pc) {
    return;
  }

  Element* root = mDocument->GetRootElement();
  if (!root) {
    return;
  }

  // TODO(emilio): It may be nicer to just invalidate stuff in a given subtree
  // for XBL sheets / Shadow DOM. Consider just enumerating bound content
  // instead and run invalidation individually, passing mRawSet for the UA /
  // User sheets.
  AutoTArray<RawServoAuthorStylesBorrowed, 20> nonDocumentStyles;

  EnumerateShadowRoots(*mDocument, [&](ShadowRoot& aShadowRoot) {
    if (auto* authorStyles = aShadowRoot.GetServoStyles()) {
      nonDocumentStyles.AppendElement(authorStyles);
    }
  });

  mDocument->BindingManager()->EnumerateBoundContentProtoBindings(
    [&](nsXBLPrototypeBinding* aProto) {
      if (auto* authorStyles = aProto->GetServoStyles()) {
        nonDocumentStyles.AppendElement(authorStyles);
      }
      return true;
    });

  Servo_InvalidateStyleForDocStateChanges(
    root, mRawSet.get(), &nonDocumentStyles, aStatesChanged.ServoValue());
}

static const MediaFeatureChangeReason kMediaFeaturesAffectingDefaultStyle =
  // Zoom changes change the meaning of em units.
  MediaFeatureChangeReason::ZoomChange |
  // Changes the meaning of em units, depending on which one is the actual
  // min-font-size.
  MediaFeatureChangeReason::MinFontSizeChange |
  // A resolution change changes the app-units-per-dev-pixels ratio, which some
  // structs (Border, Outline, Column) store for clamping. We should arguably
  // not do that, maybe doing it on layout directly, to try to avoid relying on
  // the pres context (bug 1418159).
  MediaFeatureChangeReason::ResolutionChange;

nsRestyleHint
ServoStyleSet::MediumFeaturesChanged(MediaFeatureChangeReason aReason)
{
  AutoTArray<RawServoAuthorStylesBorrowedMut, 20> nonDocumentStyles;

  EnumerateShadowRoots(*mDocument, [&](ShadowRoot& aShadowRoot) {
    if (auto* authorStyles = aShadowRoot.GetServoStyles()) {
      nonDocumentStyles.AppendElement(authorStyles);
    }
  });

  // FIXME(emilio): This is broken for XBL. See bug 1406875.
  mDocument->BindingManager()->EnumerateBoundContentProtoBindings(
    [&](nsXBLPrototypeBinding* aProto) {
      if (auto* authorStyles = aProto->GetServoStyles()) {
        nonDocumentStyles.AppendElement(authorStyles);
      }
      return true;
    });

  bool mayAffectDefaultStyle =
    bool(aReason & kMediaFeaturesAffectingDefaultStyle);

  const MediumFeaturesChangedResult result =
    Servo_StyleSet_MediumFeaturesChanged(
      mRawSet.get(), &nonDocumentStyles, mayAffectDefaultStyle);

  const bool rulesChanged =
    result.mAffectsDocumentRules || result.mAffectsNonDocumentRules;

  if (result.mAffectsDocumentRules) {
    SetStylistStyleSheetsDirty();
  }

  if (result.mAffectsNonDocumentRules) {
    SetStylistXBLStyleSheetsDirty();
  }

  if (rulesChanged) {
    return eRestyle_Subtree;
  }

  const bool viewportChanged =
    bool(aReason & MediaFeatureChangeReason::ViewportChange);
  if (result.mUsesViewportUnits && viewportChanged) {
    return eRestyle_ForceDescendants;
  }

  return nsRestyleHint(0);
}

MOZ_DEFINE_MALLOC_SIZE_OF(ServoStyleSetMallocSizeOf)
MOZ_DEFINE_MALLOC_ENCLOSING_SIZE_OF(ServoStyleSetMallocEnclosingSizeOf)

void
ServoStyleSet::AddSizeOfIncludingThis(nsWindowSizes& aSizes) const
{
  MallocSizeOf mallocSizeOf = aSizes.mState.mMallocSizeOf;

  aSizes.mLayoutStyleSetsOther += mallocSizeOf(this);

  if (mRawSet) {
    aSizes.mLayoutStyleSetsOther += mallocSizeOf(mRawSet.get());
    ServoStyleSetSizes sizes;
    // Measure mRawSet. We use ServoStyleSetMallocSizeOf rather than
    // aMallocSizeOf to distinguish in DMD's output the memory measured within
    // Servo code.
    Servo_StyleSet_AddSizeOfExcludingThis(ServoStyleSetMallocSizeOf,
                                          ServoStyleSetMallocEnclosingSizeOf,
                                          &sizes, mRawSet.get());

    // The StyleSet does not contain precomputed pseudos; they are in the UA
    // cache.
    MOZ_RELEASE_ASSERT(sizes.mPrecomputedPseudos == 0);

    aSizes.mLayoutStyleSetsStylistRuleTree += sizes.mRuleTree;
    aSizes.mLayoutStyleSetsStylistElementAndPseudosMaps +=
      sizes.mElementAndPseudosMaps;
    aSizes.mLayoutStyleSetsStylistInvalidationMap +=
      sizes.mInvalidationMap;
    aSizes.mLayoutStyleSetsStylistRevalidationSelectors +=
      sizes.mRevalidationSelectors;
    aSizes.mLayoutStyleSetsStylistOther += sizes.mOther;
  }

  if (mStyleRuleMap) {
    aSizes.mLayoutStyleSetsOther +=
      mStyleRuleMap->SizeOfIncludingThis(aSizes.mState.mMallocSizeOf);
  }

  // Measurement of the following members may be added later if DMD finds it is
  // worthwhile:
  // - mSheets
  // - mNonInheritingComputedStyles
  //
  // The following members are not measured:
  // - mDocument, because it a non-owning pointer
}

void
ServoStyleSet::SetAuthorStyleDisabled(bool aStyleDisabled)
{
  if (mAuthorStyleDisabled == aStyleDisabled) {
    return;
  }

  mAuthorStyleDisabled = aStyleDisabled;
  if (Element* root = mDocument->GetRootElement()) {
    if (nsPresContext* pc = GetPresContext()) {
      pc->RestyleManager()->PostRestyleEvent(root, eRestyle_Subtree, nsChangeHint(0));
    }
  }
  Servo_StyleSet_SetAuthorStyleDisabled(mRawSet.get(), mAuthorStyleDisabled);
  // XXX Workaround for the assertion in InvalidateStyleForDocumentStateChanges
  // which is called by nsIPresShell::SetAuthorStyleDisabled via nsIPresShell::
  // RestyleForCSSRuleChanges. It is not really necessary because we don't need
  // to rebuild stylist for this change. But we have bug around this, and we
  // may want to rethink how things should work. See bug 1437785.
  SetStylistStyleSheetsDirty();
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveStyleFor(Element* aElement,
                               LazyComputeBehavior aMayCompute)
{
  if (aMayCompute == LazyComputeBehavior::Allow) {
    PreTraverseSync();
    return ResolveStyleLazilyInternal(
        aElement, CSSPseudoElementType::NotPseudo);
  }

  return ResolveServoStyle(*aElement);
}

const ServoElementSnapshotTable&
ServoStyleSet::Snapshots()
{
  MOZ_ASSERT(GetPresContext(), "Styling a document without a shell?");
  return GetPresContext()->RestyleManager()->Snapshots();
}

void
ServoStyleSet::ResolveMappedAttrDeclarationBlocks()
{
  if (nsHTMLStyleSheet* sheet = mDocument->GetAttributeStyleSheet()) {
    sheet->CalculateMappedServoDeclarations();
  }

  mDocument->ResolveScheduledSVGPresAttrs();
}

void
ServoStyleSet::PreTraverseSync()
{
  // Get the Document's root element to ensure that the cache is valid before
  // calling into the (potentially-parallel) Servo traversal, where a cache hit
  // is necessary to avoid a data race when updating the cache.
  mozilla::Unused << mDocument->GetRootElement();

  ResolveMappedAttrDeclarationBlocks();

  nsMediaFeatures::InitSystemMetrics();

  LookAndFeel::NativeInit();

  nsPresContext* presContext = GetPresContext();
  MOZ_ASSERT(presContext,
             "For now, we don't call into here without a pres context");
  if (gfxUserFontSet* userFontSet = mDocument->GetUserFontSet()) {
    // Ensure that the @font-face data is not stale
    uint64_t generation = userFontSet->GetGeneration();
    if (generation != mUserFontSetUpdateGeneration) {
      mDocument->GetFonts()->CacheFontLoadability();
      presContext->DeviceContext()->UpdateFontCacheUserFonts(userFontSet);
      mUserFontSetUpdateGeneration = generation;
    }
  }

  MOZ_ASSERT(!StylistNeedsUpdate());
  presContext->CacheAllLangs();
}

void
ServoStyleSet::PreTraverse(ServoTraversalFlags aFlags, Element* aRoot)
{
  PreTraverseSync();

  // Process animation stuff that we should avoid doing during the parallel
  // traversal.
  nsSMILAnimationController* smilController =
    mDocument->HasAnimationController()
    ? mDocument->GetAnimationController()
    : nullptr;

  MOZ_ASSERT(GetPresContext());
  if (aRoot) {
    GetPresContext()->EffectCompositor()->PreTraverseInSubtree(aFlags, aRoot);
    if (smilController) {
      smilController->PreTraverseInSubtree(aRoot);
    }
  } else {
    GetPresContext()->EffectCompositor()->PreTraverse(aFlags);
    if (smilController) {
      smilController->PreTraverse();
    }
  }
}

static inline already_AddRefed<ComputedStyle>
ResolveStyleForTextOrFirstLetterContinuation(
    RawServoStyleSetBorrowed aStyleSet,
    ComputedStyle& aParent,
    nsAtom* aAnonBox)
{
  MOZ_ASSERT(aAnonBox == nsCSSAnonBoxes::mozText() ||
             aAnonBox == nsCSSAnonBoxes::firstLetterContinuation());
  auto inheritTarget = aAnonBox == nsCSSAnonBoxes::mozText()
    ? InheritTarget::Text
    : InheritTarget::FirstLetterContinuation;

  RefPtr<ComputedStyle> style =
    aParent.GetCachedInheritingAnonBoxStyle(aAnonBox);
  if (!style) {
    style = Servo_ComputedValues_Inherit(aStyleSet,
                                         aAnonBox,
                                         &aParent,
                                         inheritTarget).Consume();
    MOZ_ASSERT(style);
    aParent.SetCachedInheritedAnonBoxStyle(aAnonBox, style);
  }

  return style.forget();
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveStyleForText(nsIContent* aTextNode,
                                   ComputedStyle* aParentContext)
{
  MOZ_ASSERT(aTextNode && aTextNode->IsText());
  MOZ_ASSERT(aTextNode->GetParent());
  MOZ_ASSERT(aParentContext);

  return ResolveStyleForTextOrFirstLetterContinuation(
      mRawSet.get(), *aParentContext, nsCSSAnonBoxes::mozText());
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveStyleForFirstLetterContinuation(ComputedStyle* aParentContext)
{
  MOZ_ASSERT(aParentContext);

  return ResolveStyleForTextOrFirstLetterContinuation(
      mRawSet.get(), *aParentContext, nsCSSAnonBoxes::firstLetterContinuation());
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveStyleForPlaceholder()
{
  RefPtr<ComputedStyle>& cache =
    mNonInheritingComputedStyles[nsCSSAnonBoxes::NonInheriting::oofPlaceholder];
  if (cache) {
    RefPtr<ComputedStyle> retval = cache;
    return retval.forget();
  }

  RefPtr<ComputedStyle> computedValues =
    Servo_ComputedValues_Inherit(mRawSet.get(),
                                 nsCSSAnonBoxes::oofPlaceholder(),
                                 nullptr,
                                 InheritTarget::PlaceholderFrame)
                                 .Consume();
  MOZ_ASSERT(computedValues);

  cache = computedValues;
  return computedValues.forget();
}

static inline bool
LazyPseudoIsCacheable(CSSPseudoElementType aType,
                      const Element& aOriginatingElement,
                      ComputedStyle* aParentContext)
{
  return aParentContext &&
         !nsCSSPseudoElements::IsEagerlyCascadedInServo(aType) &&
         aOriginatingElement.HasServoData() &&
         !Servo_Element_IsPrimaryStyleReusedViaRuleNode(&aOriginatingElement);
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolvePseudoElementStyle(Element* aOriginatingElement,
                                         CSSPseudoElementType aType,
                                         ComputedStyle* aParentContext,
                                         Element* aPseudoElement)
{
  // Runs from frame construction, this should have clean styles already, except
  // with non-lazy FC...
  UpdateStylistIfNeeded();
  MOZ_ASSERT(aType < CSSPseudoElementType::Count);

  RefPtr<ComputedStyle> computedValues;

  if (aPseudoElement) {
    MOZ_ASSERT(aType == aPseudoElement->GetPseudoElementType());
    computedValues =
      Servo_ResolveStyle(aPseudoElement, mRawSet.get()).Consume();
  } else {
    bool cacheable =
      LazyPseudoIsCacheable(aType, *aOriginatingElement, aParentContext);
    computedValues =
      cacheable ? aParentContext->GetCachedLazyPseudoStyle(aType) : nullptr;

    if (!computedValues) {
      computedValues = Servo_ResolvePseudoStyle(aOriginatingElement,
                                                aType,
                                                /* is_probe = */ false,
                                                aParentContext,
                                                mRawSet.get()).Consume();
      if (cacheable) {
        aParentContext->SetCachedLazyPseudoStyle(computedValues);
      }
    }
  }

  MOZ_ASSERT(computedValues);
  return computedValues.forget();
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveStyleLazily(Element* aElement,
                                  CSSPseudoElementType aPseudoType,
                                  StyleRuleInclusion aRuleInclusion)
{
  PreTraverseSync();

  return ResolveStyleLazilyInternal(aElement, aPseudoType,
                                    aRuleInclusion);
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveInheritingAnonymousBoxStyle(nsAtom* aPseudoTag,
                                                  ComputedStyle* aParentContext)
{
  MOZ_ASSERT(nsCSSAnonBoxes::IsAnonBox(aPseudoTag) &&
             !nsCSSAnonBoxes::IsNonInheritingAnonBox(aPseudoTag));
  MOZ_ASSERT_IF(aParentContext, !StylistNeedsUpdate());

  UpdateStylistIfNeeded();

  RefPtr<ComputedStyle> style = nullptr;

  if (aParentContext) {
    style = aParentContext->GetCachedInheritingAnonBoxStyle(aPseudoTag);
  }

  if (!style) {
    style =
      Servo_ComputedValues_GetForAnonymousBox(aParentContext,
                                              aPseudoTag,
                                              mRawSet.get()).Consume();
    MOZ_ASSERT(style);
    if (aParentContext) {
      aParentContext->SetCachedInheritedAnonBoxStyle(aPseudoTag, style);
    }
  }

  return style.forget();
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveNonInheritingAnonymousBoxStyle(nsAtom* aPseudoTag)
{
  MOZ_ASSERT(nsCSSAnonBoxes::IsAnonBox(aPseudoTag) &&
             nsCSSAnonBoxes::IsNonInheritingAnonBox(aPseudoTag));
  MOZ_ASSERT(aPseudoTag != nsCSSAnonBoxes::pageContent(),
             "If nsCSSAnonBoxes::pageContent() ends up non-inheriting, check "
             "whether we need to do anything to move the "
             "@page handling from ResolveInheritingAnonymousBoxStyle to "
             "ResolveNonInheritingAnonymousBoxStyle");

  nsCSSAnonBoxes::NonInheriting type =
    nsCSSAnonBoxes::NonInheritingTypeForPseudoTag(aPseudoTag);
  RefPtr<ComputedStyle>& cache = mNonInheritingComputedStyles[type];
  if (cache) {
    RefPtr<ComputedStyle> retval = cache;
    return retval.forget();
  }

  UpdateStylistIfNeeded();

  // We always want to skip parent-based display fixup here.  It never makes
  // sense for non-inheriting anonymous boxes.  (Static assertions in
  // nsCSSAnonBoxes.cpp ensure that all non-inheriting non-anonymous boxes
  // are indeed annotated as skipping this fixup.)
  MOZ_ASSERT(!nsCSSAnonBoxes::IsNonInheritingAnonBox(nsCSSAnonBoxes::viewport()),
             "viewport needs fixup to handle blockifying it");
  RefPtr<ComputedStyle> computedValues =
    Servo_ComputedValues_GetForAnonymousBox(nullptr,
                                            aPseudoTag,
                                            mRawSet.get()).Consume();
#ifdef DEBUG
  if (!computedValues) {
    nsString pseudo;
    aPseudoTag->ToString(pseudo);
    NS_ERROR(nsPrintfCString("stylo: could not get anon-box: %s",
             NS_ConvertUTF16toUTF8(pseudo).get()).get());
    MOZ_CRASH();
  }
#endif

  cache = computedValues;
  return computedValues.forget();
}

#ifdef MOZ_XUL
already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveXULTreePseudoStyle(dom::Element* aParentElement,
                                         nsCSSAnonBoxPseudoStaticAtom* aPseudoTag,
                                         ComputedStyle* aParentContext,
                                         const AtomArray& aInputWord)
{
  MOZ_ASSERT(nsCSSAnonBoxes::IsTreePseudoElement(aPseudoTag));
  MOZ_ASSERT(aParentContext);
  MOZ_ASSERT(!StylistNeedsUpdate());

  return Servo_ComputedValues_ResolveXULTreePseudoStyle(
      aParentElement,
      aPseudoTag,
      aParentContext,
      &aInputWord,
      mRawSet.get()
  ).Consume();
}
#endif

// manage the set of style sheets in the style set
nsresult
ServoStyleSet::AppendStyleSheet(SheetType aType, StyleSheet* aSheet)
{
  MOZ_ASSERT(aSheet);
  MOZ_ASSERT(aSheet->IsApplicable());
  MOZ_ASSERT(IsCSSSheetType(aType));
  MOZ_ASSERT(aSheet->RawContents(), "Raw sheet should be in place before insertion.");

  RemoveSheetOfType(aType, aSheet);
  AppendSheetOfType(aType, aSheet);

  if (mRawSet) {
    // Maintain a mirrored list of sheets on the servo side.
    // Servo will remove aSheet from its original position as part of the call
    // to Servo_StyleSet_AppendStyleSheet.
    Servo_StyleSet_AppendStyleSheet(mRawSet.get(), aSheet);
    SetStylistStyleSheetsDirty();
  }

  if (mStyleRuleMap) {
    mStyleRuleMap->SheetAdded(*aSheet);
  }

  return NS_OK;
}

nsresult
ServoStyleSet::PrependStyleSheet(SheetType aType, StyleSheet* aSheet)
{
  MOZ_ASSERT(aSheet);
  MOZ_ASSERT(aSheet->IsApplicable());
  MOZ_ASSERT(IsCSSSheetType(aType));
  MOZ_ASSERT(aSheet->RawContents(),
             "Raw sheet should be in place before insertion.");

  RemoveSheetOfType(aType, aSheet);
  PrependSheetOfType(aType, aSheet);

  if (mRawSet) {
    // Maintain a mirrored list of sheets on the servo side.
    // Servo will remove aSheet from its original position as part of the call
    // to Servo_StyleSet_PrependStyleSheet.
    Servo_StyleSet_PrependStyleSheet(mRawSet.get(), aSheet);
    SetStylistStyleSheetsDirty();
  }

  if (mStyleRuleMap) {
    mStyleRuleMap->SheetAdded(*aSheet);
  }

  return NS_OK;
}

nsresult
ServoStyleSet::RemoveStyleSheet(SheetType aType, StyleSheet* aSheet)
{
  MOZ_ASSERT(aSheet);
  MOZ_ASSERT(IsCSSSheetType(aType));

  RemoveSheetOfType(aType, aSheet);
  if (mRawSet) {
    // Maintain a mirrored list of sheets on the servo side.
    Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), aSheet);
    SetStylistStyleSheetsDirty();
  }

  if (mStyleRuleMap) {
    mStyleRuleMap->SheetRemoved(*aSheet);
  }

  return NS_OK;
}

nsresult
ServoStyleSet::ReplaceSheets(SheetType aType,
                             const nsTArray<RefPtr<StyleSheet>>& aNewSheets)
{
  // Gecko uses a two-dimensional array keyed by sheet type, whereas Servo
  // stores a flattened list. This makes ReplaceSheets a pretty clunky thing
  // to express. If the need ever arises, we can easily make this more efficent,
  // probably by aligning the representations better between engines.

  SetStylistStyleSheetsDirty();

  // Remove all the existing sheets first.
  for (const auto& sheet : mSheets[aType]) {
    sheet->DropStyleSet(this);
    if (mRawSet) {
      Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), sheet);
    }
  }
  mSheets[aType].Clear();

  // Add in all the new sheets.
  for (auto& sheet : aNewSheets) {
    AppendSheetOfType(aType, sheet);
    if (mRawSet) {
      MOZ_ASSERT(sheet->RawContents(), "Raw sheet should be in place before replacement.");
      Servo_StyleSet_AppendStyleSheet(mRawSet.get(), sheet);
    }
  }

  // Just don't bother calling SheetRemoved / SheetAdded, and recreate the rule
  // map when needed.
  mStyleRuleMap = nullptr;
  return NS_OK;
}

nsresult
ServoStyleSet::InsertStyleSheetBefore(SheetType aType,
                                      StyleSheet* aNewSheet,
                                      StyleSheet* aReferenceSheet)
{
  MOZ_ASSERT(aNewSheet);
  MOZ_ASSERT(aReferenceSheet);
  MOZ_ASSERT(aNewSheet->IsApplicable());
  MOZ_ASSERT(aNewSheet != aReferenceSheet, "Can't place sheet before itself.");
  MOZ_ASSERT(aNewSheet->RawContents(), "Raw sheet should be in place before insertion.");
  MOZ_ASSERT(aReferenceSheet->RawContents(), "Reference sheet should have a raw sheet.");

  // Servo will remove aNewSheet from its original position as part of the
  // call to Servo_StyleSet_InsertStyleSheetBefore.
  RemoveSheetOfType(aType, aNewSheet);
  InsertSheetOfType(aType, aNewSheet, aReferenceSheet);

  if (mRawSet) {
    // Maintain a mirrored list of sheets on the servo side.
    Servo_StyleSet_InsertStyleSheetBefore(
        mRawSet.get(), aNewSheet, aReferenceSheet);
    SetStylistStyleSheetsDirty();
  }

  if (mStyleRuleMap) {
    mStyleRuleMap->SheetAdded(*aNewSheet);
  }

  return NS_OK;
}

int32_t
ServoStyleSet::SheetCount(SheetType aType) const
{
  MOZ_ASSERT(IsCSSSheetType(aType));
  return mSheets[aType].Length();
}

StyleSheet*
ServoStyleSet::StyleSheetAt(SheetType aType, int32_t aIndex) const
{
  MOZ_ASSERT(IsCSSSheetType(aType));
  return mSheets[aType][aIndex];
}

void
ServoStyleSet::AppendAllNonDocumentAuthorSheets(nsTArray<StyleSheet*>& aArray) const
{
  if (mDocument) {
    mDocument->BindingManager()->AppendAllSheets(aArray);
    EnumerateShadowRoots(*mDocument, [&](ShadowRoot& aShadowRoot) {
      for (auto index : IntegerRange(aShadowRoot.SheetCount())) {
        aArray.AppendElement(aShadowRoot.SheetAt(index));
      }
    });
  }
}

nsresult
ServoStyleSet::RemoveDocStyleSheet(StyleSheet* aSheet)
{
  return RemoveStyleSheet(SheetType::Doc, aSheet);
}

nsresult
ServoStyleSet::AddDocStyleSheet(StyleSheet* aSheet, nsIDocument* aDocument)
{
  MOZ_ASSERT(aSheet->IsApplicable());
  MOZ_ASSERT(aSheet->RawContents(), "Raw sheet should be in place by this point.");

  RefPtr<StyleSheet> strong(aSheet);

  RemoveSheetOfType(SheetType::Doc, aSheet);

  size_t index =
    aDocument->FindDocStyleSheetInsertionPoint(mSheets[SheetType::Doc], *aSheet);

  if (index < mSheets[SheetType::Doc].Length()) {
    // This case is insert before.
    StyleSheet *beforeSheet = mSheets[SheetType::Doc][index];
    InsertSheetOfType(SheetType::Doc, aSheet, beforeSheet);

    if (mRawSet) {
      // Maintain a mirrored list of sheets on the servo side.
      Servo_StyleSet_InsertStyleSheetBefore(mRawSet.get(), aSheet, beforeSheet);
      SetStylistStyleSheetsDirty();
    }
  } else {
    // This case is append.
    AppendSheetOfType(SheetType::Doc, aSheet);

    if (mRawSet) {
      // Maintain a mirrored list of sheets on the servo side.
      Servo_StyleSet_AppendStyleSheet(mRawSet.get(), aSheet);
      SetStylistStyleSheetsDirty();
    }
  }

  if (mStyleRuleMap) {
    mStyleRuleMap->SheetAdded(*aSheet);
  }

  return NS_OK;
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ProbePseudoElementStyle(const Element& aOriginatingElement,
                                       CSSPseudoElementType aType,
                                       ComputedStyle* aParentContext)
{
  // Runs from frame construction, this should have clean styles already, except
  // with non-lazy FC...
  UpdateStylistIfNeeded();

  // NB: We ignore aParentContext, because in some cases
  // (first-line/first-letter on anonymous box blocks) Gecko passes something
  // nonsensical there.  In all other cases we want to inherit directly from
  // aOriginatingElement's styles anyway.
  MOZ_ASSERT(aType < CSSPseudoElementType::Count);

  bool cacheable =
    LazyPseudoIsCacheable(aType, aOriginatingElement, aParentContext);

  RefPtr<ComputedStyle> computedValues =
    cacheable ? aParentContext->GetCachedLazyPseudoStyle(aType) : nullptr;
  if (!computedValues) {
    computedValues = Servo_ResolvePseudoStyle(&aOriginatingElement,
                                              aType,
                                              /* is_probe = */ true,
                                              nullptr,
                                              mRawSet.get()).Consume();
    if (!computedValues) {
      return nullptr;
    }

    if (cacheable) {
      // NB: We don't need to worry about the before/after handling below
      // because those are eager and thus not |cacheable| anyway.
      aParentContext->SetCachedLazyPseudoStyle(computedValues);
    }
  }

  // For :before and :after pseudo-elements, having display: none or no
  // 'content' property is equivalent to not having the pseudo-element
  // at all.
  bool isBeforeOrAfter = aType == CSSPseudoElementType::before ||
                         aType == CSSPseudoElementType::after;
  if (isBeforeOrAfter) {
    const nsStyleDisplay* display = computedValues->ComputedData()->GetStyleDisplay();
    const nsStyleContent* content = computedValues->ComputedData()->GetStyleContent();
    if (display->mDisplay == StyleDisplay::None ||
        content->ContentCount() == 0) {
      return nullptr;
    }
  }

  return computedValues.forget();
}

bool
ServoStyleSet::StyleDocument(ServoTraversalFlags aFlags)
{
  MOZ_ASSERT(GetPresContext(), "Styling a document without a shell?");

  if (!mDocument->GetServoRestyleRoot()) {
    return false;
  }

  PreTraverse(aFlags);
  AutoPrepareTraversal guard(this);
  const SnapshotTable& snapshots = Snapshots();

  // Restyle the document from the root element and each of the document level
  // NAC subtree roots.
  bool postTraversalRequired = false;

  Element* rootElement = mDocument->GetRootElement();
  MOZ_ASSERT_IF(rootElement, rootElement->HasServoData());

  if (ShouldTraverseInParallel()) {
    aFlags |= ServoTraversalFlags::ParallelTraversal;
  }

  // Do the first traversal.
  DocumentStyleRootIterator iter(mDocument->GetServoRestyleRoot());
  while (Element* root = iter.GetNextStyleRoot()) {
    MOZ_ASSERT(MayTraverseFrom(root));

    Element* parent = root->GetFlattenedTreeParentElementForStyle();
    MOZ_ASSERT_IF(parent,
                  !parent->HasAnyOfFlags(Element::kAllServoDescendantBits));

    postTraversalRequired |=
      Servo_TraverseSubtree(root, mRawSet.get(), &snapshots, aFlags);
    postTraversalRequired |=
      root->HasAnyOfFlags(Element::kAllServoDescendantBits | NODE_NEEDS_FRAME);

    if (parent) {
      MOZ_ASSERT(root == mDocument->GetServoRestyleRoot());
      if (parent->HasDirtyDescendantsForServo()) {
        // If any style invalidation was triggered in our siblings, then we may
        // need to post-traverse them, even if the root wasn't restyled after
        // all.
        uint32_t existingBits = mDocument->GetServoRestyleRootDirtyBits();
        // We need to propagate the existing bits to the parent.
        parent->SetFlags(existingBits);
        mDocument->SetServoRestyleRoot(
            parent,
            existingBits | ELEMENT_HAS_DIRTY_DESCENDANTS_FOR_SERVO);
        postTraversalRequired = true;
      }
    }
  }

  // If there are still animation restyles needed, trigger a second traversal to
  // update CSS animations or transitions' styles.
  //
  // Note that we need to check the style root again, because doing another
  // PreTraverse on the EffectCompositor might alter the style root. But we
  // don't need to worry about NAC, since document-level NAC shouldn't have
  // animations.
  //
  // We don't need to do this for SMIL since SMIL only updates its animation
  // values once at the begin of a tick. As a result, even if the previous
  // traversal caused, for example, the font-size to change, the SMIL style
  // won't be updated until the next tick anyway.
  if (GetPresContext()->EffectCompositor()->PreTraverse(aFlags)) {
    nsINode* styleRoot = mDocument->GetServoRestyleRoot();
    Element* root = styleRoot->IsElement() ? styleRoot->AsElement() : rootElement;

    postTraversalRequired |=
      Servo_TraverseSubtree(root, mRawSet.get(), &snapshots, aFlags);
    postTraversalRequired |=
      root->HasAnyOfFlags(Element::kAllServoDescendantBits | NODE_NEEDS_FRAME);
  }

  return postTraversalRequired;
}

void
ServoStyleSet::StyleNewSubtree(Element* aRoot)
{
  MOZ_ASSERT(GetPresContext());
  MOZ_ASSERT(!aRoot->HasServoData());
  MOZ_ASSERT(aRoot->GetFlattenedTreeParentNodeForStyle(),
             "Not in the flat tree? Fishy!");
  PreTraverseSync();
  AutoPrepareTraversal guard(this);

  // Do the traversal. The snapshots will not be used.
  const SnapshotTable& snapshots = Snapshots();
  auto flags = ServoTraversalFlags::Empty;
  if (ShouldTraverseInParallel()) {
    flags |= ServoTraversalFlags::ParallelTraversal;
  }

  DebugOnly<bool> postTraversalRequired =
    Servo_TraverseSubtree(aRoot, mRawSet.get(), &snapshots, flags);
  MOZ_ASSERT(!postTraversalRequired);

  // Annoyingly, the newly-styled content may have animations that need
  // starting, which requires traversing them again. Mark the elements
  // that need animation processing, then do a forgetful traversal to
  // update the styles and clear the animation bits.
  if (GetPresContext()->EffectCompositor()->PreTraverseInSubtree(flags, aRoot)) {
    postTraversalRequired =
      Servo_TraverseSubtree(aRoot, mRawSet.get(), &snapshots,
                            ServoTraversalFlags::AnimationOnly |
                            ServoTraversalFlags::Forgetful |
                            ServoTraversalFlags::ClearAnimationOnlyDirtyDescendants);
    MOZ_ASSERT(!postTraversalRequired);
  }
}

void
ServoStyleSet::MarkOriginsDirty(OriginFlags aChangedOrigins)
{
  if (MOZ_UNLIKELY(!mRawSet)) {
    return;
  }

  SetStylistStyleSheetsDirty();
  Servo_StyleSet_NoteStyleSheetsChanged(mRawSet.get(), aChangedOrigins);
}

void
ServoStyleSet::SetStylistStyleSheetsDirty()
{
  // Note that there's another hidden mutator of mStylistState for XBL style
  // sets in MediumFeaturesChanged...
  //
  // We really need to stop using a full-blown StyleSet there...
  mStylistState |= StylistState::StyleSheetsDirty;

  // We need to invalidate cached style in getComputedStyle for undisplayed
  // elements, since we don't know if any of the style sheet change that we
  // do would affect undisplayed elements.
  if (nsPresContext* presContext = GetPresContext()) {
    // XBL sheets don't have a pres context, but invalidating the restyle
    // generation in that case is handled by SetXBLStyleSheetsDirty in the
    // "master" stylist.
    presContext->RestyleManager()->IncrementUndisplayedRestyleGeneration();
  }
}

void
ServoStyleSet::SetStylistXBLStyleSheetsDirty()
{
  mStylistState |= StylistState::XBLStyleSheetsDirty;

  // We need to invalidate cached style in getComputedStyle for undisplayed
  // elements, since we don't know if any of the style sheet change that we
  // do would affect undisplayed elements.
  MOZ_ASSERT(GetPresContext());
  GetPresContext()->RestyleManager()->IncrementUndisplayedRestyleGeneration();
}

void
ServoStyleSet::RuleAdded(StyleSheet& aSheet, css::Rule& aRule)
{
  if (mStyleRuleMap) {
    mStyleRuleMap->RuleAdded(aSheet, aRule);
  }

  // FIXME(emilio): Could be more granular based on aRule.
  MarkOriginsDirty(aSheet.GetOrigin());
}

void
ServoStyleSet::RuleRemoved(StyleSheet& aSheet, css::Rule& aRule)
{
  if (mStyleRuleMap) {
    mStyleRuleMap->RuleRemoved(aSheet, aRule);
  }

  // FIXME(emilio): Could be more granular based on aRule.
  MarkOriginsDirty(aSheet.GetOrigin());
}

void
ServoStyleSet::RuleChanged(StyleSheet& aSheet, css::Rule* aRule)
{
  // FIXME(emilio): Could be more granular based on aRule.
  MarkOriginsDirty(aSheet.GetOrigin());
}

#ifdef DEBUG
void
ServoStyleSet::AssertTreeIsClean()
{
  DocumentStyleRootIterator iter(mDocument);
  while (Element* root = iter.GetNextStyleRoot()) {
    Servo_AssertTreeIsClean(root);
  }
}
#endif

bool
ServoStyleSet::GetKeyframesForName(const Element& aElement,
                                   const ComputedStyle& aStyle,
                                   nsAtom* aName,
                                   const nsTimingFunction& aTimingFunction,
                                   nsTArray<Keyframe>& aKeyframes)
{
  MOZ_ASSERT(!StylistNeedsUpdate());
  return Servo_StyleSet_GetKeyframesForName(mRawSet.get(),
                                            &aElement,
                                            &aStyle,
                                            aName,
                                            &aTimingFunction,
                                            &aKeyframes);
}

nsTArray<ComputedKeyframeValues>
ServoStyleSet::GetComputedKeyframeValuesFor(
  const nsTArray<Keyframe>& aKeyframes,
  Element* aElement,
  const mozilla::ComputedStyle* aStyle)
{
  nsTArray<ComputedKeyframeValues> result(aKeyframes.Length());

  // Construct each nsTArray<PropertyStyleAnimationValuePair> here.
  result.AppendElements(aKeyframes.Length());

  Servo_GetComputedKeyframeValues(&aKeyframes,
                                  aElement,
                                  aStyle,
                                  mRawSet.get(),
                                  &result);
  return result;
}

void
ServoStyleSet::GetAnimationValues(
  RawServoDeclarationBlock* aDeclarations,
  Element* aElement,
  const ComputedStyle* aComputedStyle,
  nsTArray<RefPtr<RawServoAnimationValue>>& aAnimationValues)
{
  // Servo_GetAnimationValues below won't handle ignoring existing element
  // data for bfcached documents. (See comment in ResolveStyleLazily
  // about these bfcache issues.)
  Servo_GetAnimationValues(aDeclarations,
                           aElement,
                           aComputedStyle,
                           mRawSet.get(),
                           &aAnimationValues);
}

already_AddRefed<ComputedStyle>
ServoStyleSet::GetBaseContextForElement(
  Element* aElement,
  const ComputedStyle* aStyle)
{
  return Servo_StyleSet_GetBaseComputedValuesForElement(mRawSet.get(),
                                                        aElement,
                                                        aStyle,
                                                        &Snapshots()).Consume();
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveServoStyleByAddingAnimation(
  Element* aElement,
  const ComputedStyle* aStyle,
  RawServoAnimationValue* aAnimationValue)
{
  return Servo_StyleSet_GetComputedValuesByAddingAnimation(
    mRawSet.get(),
    aElement,
    aStyle,
    &Snapshots(),
    aAnimationValue).Consume();
}

already_AddRefed<RawServoAnimationValue>
ServoStyleSet::ComputeAnimationValue(
  Element* aElement,
  RawServoDeclarationBlock* aDeclarations,
  const mozilla::ComputedStyle* aStyle)
{
  return Servo_AnimationValue_Compute(aElement,
                                      aDeclarations,
                                      aStyle,
                                      mRawSet.get()).Consume();
}

bool
ServoStyleSet::EnsureUniqueInnerOnCSSSheets()
{
  using SheetOwner = Variant<ServoStyleSet*, nsXBLPrototypeBinding*, ShadowRoot*>;

  AutoTArray<Pair<StyleSheet*, SheetOwner>, 32> queue;
  for (auto& entryArray : mSheets) {
    for (auto& sheet : entryArray) {
      StyleSheet* downcasted = sheet;
      queue.AppendElement(MakePair(downcasted, SheetOwner { this }));
    }
  }

  EnumerateShadowRoots(*mDocument, [&](ShadowRoot& aShadowRoot) {
    for (auto index : IntegerRange(aShadowRoot.SheetCount())) {
      queue.AppendElement(
        MakePair(aShadowRoot.SheetAt(index), SheetOwner { &aShadowRoot }));
    }
  });

  mDocument->BindingManager()->EnumerateBoundContentProtoBindings(
      [&](nsXBLPrototypeBinding* aProto) {
        AutoTArray<StyleSheet*, 3> sheets;
        aProto->AppendStyleSheetsTo(sheets);
        for (auto* sheet : sheets) {
          queue.AppendElement(MakePair(sheet, SheetOwner { aProto }));
        }
        return true;
      });

  bool anyNonDocStyleChanged = false;
  while (!queue.IsEmpty()) {
    uint32_t idx = queue.Length() - 1;
    auto* sheet = queue[idx].first();
    SheetOwner owner = queue[idx].second();
    queue.RemoveElementAt(idx);

    if (!sheet->HasUniqueInner()) {
      RawServoAuthorStyles* authorStyles = nullptr;
      if (owner.is<ShadowRoot*>()) {
        authorStyles = owner.as<ShadowRoot*>()->GetServoStyles();
      } else if (owner.is<nsXBLPrototypeBinding*>()) {
        authorStyles = owner.as<nsXBLPrototypeBinding*>()->GetServoStyles();
      }

      if (authorStyles) {
        Servo_AuthorStyles_ForceDirty(authorStyles);
        mNeedsRestyleAfterEnsureUniqueInner = true;
        anyNonDocStyleChanged = true;
      }
    }

    // Only call EnsureUniqueInner for complete sheets. If we do call it on
    // incomplete sheets, we'll cause problems when the sheet is actually
    // loaded. We don't care about incomplete sheets here anyway, because this
    // method is only invoked by nsPresContext::EnsureSafeToHandOutCSSRules.
    // The CSSRule objects we are handing out won't contain any rules derived
    // from incomplete sheets (because they aren't yet applied in styling).
    if (sheet->IsComplete()) {
      sheet->EnsureUniqueInner();
    }

    // Enqueue all the sheet's children.
    AutoTArray<StyleSheet*, 3> children;
    sheet->AppendAllChildSheets(children);
    for (auto* sheet : children) {
      queue.AppendElement(MakePair(sheet, owner));
    }
  }

  if (anyNonDocStyleChanged) {
    SetStylistXBLStyleSheetsDirty();
  }

  if (mNeedsRestyleAfterEnsureUniqueInner) {
    // TODO(emilio): We could make this faster if needed tracking the specific
    // origins and all that, but the only caller of this doesn't seem to really
    // care about perf.
    MarkOriginsDirty(OriginFlags::All);
  }
  bool res = mNeedsRestyleAfterEnsureUniqueInner;
  mNeedsRestyleAfterEnsureUniqueInner = false;
  return res;
}

void
ServoStyleSet::ClearCachedStyleData()
{
  ClearNonInheritingComputedStyles();
  Servo_StyleSet_RebuildCachedData(mRawSet.get());
}

void
ServoStyleSet::CompatibilityModeChanged()
{
  Servo_StyleSet_CompatModeChanged(mRawSet.get());
  SetStylistStyleSheetsDirty();
}

void
ServoStyleSet::ClearNonInheritingComputedStyles()
{
  for (RefPtr<ComputedStyle>& ptr : mNonInheritingComputedStyles) {
    ptr = nullptr;
  }
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveStyleLazilyInternal(Element* aElement,
                                          CSSPseudoElementType aPseudoType,
                                          StyleRuleInclusion aRuleInclusion)
{
  MOZ_ASSERT(GetPresContext(),
             "For now, no style resolution without a pres context");
  GetPresContext()->EffectCompositor()->PreTraverse(aElement, aPseudoType);
  MOZ_ASSERT(!StylistNeedsUpdate());

  AutoSetInServoTraversal guard(this);

  /**
   * NB: This is needed because we process animations and transitions on the
   * pseudo-elements themselves, not on the parent's EagerPseudoStyles.
   *
   * That means that that style doesn't account for animations, and we can't do
   * that easily from the traversal without doing wasted work.
   *
   * As such, we just lie here a bit, which is the entrypoint of
   * getComputedStyle, the only API where this can be observed, to look at the
   * style of the pseudo-element if it exists instead.
   */
  Element* elementForStyleResolution = aElement;
  CSSPseudoElementType pseudoTypeForStyleResolution = aPseudoType;
  if (aPseudoType == CSSPseudoElementType::before) {
    if (Element* pseudo = nsLayoutUtils::GetBeforePseudo(aElement)) {
      elementForStyleResolution = pseudo;
      pseudoTypeForStyleResolution = CSSPseudoElementType::NotPseudo;
    }
  } else if (aPseudoType == CSSPseudoElementType::after) {
    if (Element* pseudo = nsLayoutUtils::GetAfterPseudo(aElement)) {
      elementForStyleResolution = pseudo;
      pseudoTypeForStyleResolution = CSSPseudoElementType::NotPseudo;
    }
  }

  RefPtr<ComputedStyle> computedValues =
    Servo_ResolveStyleLazily(elementForStyleResolution,
                             pseudoTypeForStyleResolution,
                             aRuleInclusion,
                             &Snapshots(),
                             mRawSet.get()).Consume();

  if (GetPresContext()->EffectCompositor()->PreTraverse(aElement, aPseudoType)) {
    computedValues =
      Servo_ResolveStyleLazily(elementForStyleResolution,
                               pseudoTypeForStyleResolution,
                               aRuleInclusion,
                               &Snapshots(),
                               mRawSet.get()).Consume();
  }

  MOZ_DIAGNOSTIC_ASSERT(computedValues->PresContextForFrame() == GetPresContext() ||
                        aElement->OwnerDoc()->GetBFCacheEntry());

  return computedValues.forget();
}

bool
ServoStyleSet::AppendFontFaceRules(nsTArray<nsFontFaceRuleContainer>& aArray)
{
  // TODO(emilio): Can we make this so this asserts instead?
  UpdateStylistIfNeeded();
  Servo_StyleSet_GetFontFaceRules(mRawSet.get(), &aArray);
  return true;
}

const RawServoCounterStyleRule*
ServoStyleSet::CounterStyleRuleForName(nsAtom* aName)
{
  MOZ_ASSERT(!StylistNeedsUpdate());
  return Servo_StyleSet_GetCounterStyleRule(mRawSet.get(), aName);
}

already_AddRefed<gfxFontFeatureValueSet>
ServoStyleSet::BuildFontFeatureValueSet()
{
  MOZ_ASSERT(!StylistNeedsUpdate());
  RefPtr<gfxFontFeatureValueSet> set =
    Servo_StyleSet_BuildFontFeatureValueSet(mRawSet.get());
  return set.forget();
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ResolveForDeclarations(
  const ComputedStyle* aParentOrNull,
  RawServoDeclarationBlockBorrowed aDeclarations)
{
  // No need to update the stylist, we're only cascading aDeclarations.
  return Servo_StyleSet_ResolveForDeclarations(mRawSet.get(),
                                               aParentOrNull,
                                               aDeclarations).Consume();
}

void
ServoStyleSet::UpdateStylist()
{
  MOZ_ASSERT(StylistNeedsUpdate());

  if (mStylistState & StylistState::StyleSheetsDirty) {
    // There's no need to compute invalidations and such for an XBL styleset,
    // since they are loaded and unloaded synchronously, and they don't have to
    // deal with dynamic content changes.
    Element* root = mDocument->GetRootElement();
    const ServoElementSnapshotTable* snapshots = nullptr;
    if (nsPresContext* pc = GetPresContext()) {
      snapshots = &pc->RestyleManager()->Snapshots();
    }
    Servo_StyleSet_FlushStyleSheets(mRawSet.get(), root, snapshots);
  }

  if (MOZ_UNLIKELY(mStylistState & StylistState::XBLStyleSheetsDirty)) {
    MOZ_ASSERT(GetPresContext(), "How did they get dirty?");

    EnumerateShadowRoots(*mDocument, [&](ShadowRoot& aShadowRoot) {
      if (auto* authorStyles = aShadowRoot.GetServoStyles()) {
        Servo_AuthorStyles_Flush(authorStyles, mRawSet.get());
      }
    });

    mDocument->BindingManager()->EnumerateBoundContentProtoBindings(
      [&](nsXBLPrototypeBinding* aProto) {
        if (auto* authorStyles = aProto->GetServoStyles()) {
          Servo_AuthorStyles_Flush(authorStyles, mRawSet.get());
        }
        return true;
      });
  }

  mStylistState = StylistState::NotDirty;
}

void
ServoStyleSet::MaybeGCRuleTree()
{
  MOZ_ASSERT(NS_IsMainThread());
  Servo_MaybeGCRuleTree(mRawSet.get());
}

/* static */ bool
ServoStyleSet::MayTraverseFrom(const Element* aElement)
{
  MOZ_ASSERT(aElement->IsInComposedDoc());
  nsINode* parent = aElement->GetFlattenedTreeParentNodeForStyle();
  if (!parent) {
    return false;
  }

  if (!parent->IsElement()) {
    MOZ_ASSERT(parent->IsDocument());
    return true;
  }

  if (!parent->AsElement()->HasServoData()) {
    return false;
  }

  return !Servo_Element_IsDisplayNone(parent->AsElement());
}

bool
ServoStyleSet::ShouldTraverseInParallel() const
{
  MOZ_ASSERT(mDocument->GetShell(), "Styling a document without a shell?");
  if (!mDocument->GetShell()->IsActive()) {
    return false;
  }
#ifdef MOZ_GECKO_PROFILER
  if (profiler_feature_active(ProfilerFeature::SequentialStyle)) {
    return false;
  }
#endif
  return true;
}

void
ServoStyleSet::PrependSheetOfType(SheetType aType, StyleSheet* aSheet)
{
  aSheet->AddStyleSet(this);
  mSheets[aType].InsertElementAt(0, aSheet);
}

void
ServoStyleSet::AppendSheetOfType(SheetType aType, StyleSheet* aSheet)
{
  aSheet->AddStyleSet(this);
  mSheets[aType].AppendElement(aSheet);
}

void
ServoStyleSet::InsertSheetOfType(SheetType aType,
                                 StyleSheet* aSheet,
                                 StyleSheet* aBeforeSheet)
{
  for (uint32_t i = 0; i < mSheets[aType].Length(); ++i) {
    if (mSheets[aType][i] == aBeforeSheet) {
      aSheet->AddStyleSet(this);
      mSheets[aType].InsertElementAt(i, aSheet);
      return;
    }
  }
}

void
ServoStyleSet::RemoveSheetOfType(SheetType aType, StyleSheet* aSheet)
{
  for (uint32_t i = 0; i < mSheets[aType].Length(); ++i) {
    if (mSheets[aType][i] == aSheet) {
      aSheet->DropStyleSet(this);
      mSheets[aType].RemoveElementAt(i);
    }
  }
}

void
ServoStyleSet::RunPostTraversalTasks()
{
  MOZ_ASSERT(!IsInServoTraversal());

  if (mPostTraversalTasks.IsEmpty()) {
    return;
  }

  nsTArray<PostTraversalTask> tasks;
  tasks.SwapElements(mPostTraversalTasks);

  for (auto& task : tasks) {
    task.Run();
  }
}

ServoStyleRuleMap*
ServoStyleSet::StyleRuleMap()
{
  if (!mStyleRuleMap) {
    mStyleRuleMap = MakeUnique<ServoStyleRuleMap>();
  }
  mStyleRuleMap->EnsureTable(*this);
  return mStyleRuleMap.get();
}

bool
ServoStyleSet::MightHaveAttributeDependency(const Element& aElement,
                                            nsAtom* aAttribute) const
{
  return Servo_StyleSet_MightHaveAttributeDependency(
      mRawSet.get(), &aElement, aAttribute);
}

bool
ServoStyleSet::HasStateDependency(const Element& aElement,
                                  EventStates aState) const
{
  return Servo_StyleSet_HasStateDependency(
      mRawSet.get(), &aElement, aState.ServoValue());
}

bool
ServoStyleSet::HasDocumentStateDependency(EventStates aState) const
{
  return Servo_StyleSet_HasDocumentStateDependency(
      mRawSet.get(), aState.ServoValue());
}

already_AddRefed<ComputedStyle>
ServoStyleSet::ReparentComputedStyle(ComputedStyle* aComputedStyle,
                                     ComputedStyle* aNewParent,
                                     ComputedStyle* aNewParentIgnoringFirstLine,
                                     ComputedStyle* aNewLayoutParent,
                                     Element* aElement)
{
  return Servo_ReparentStyle(aComputedStyle, aNewParent,
                             aNewParentIgnoringFirstLine, aNewLayoutParent,
                             aElement, mRawSet.get()).Consume();
}

NS_IMPL_ISUPPORTS(UACacheReporter, nsIMemoryReporter)

MOZ_DEFINE_MALLOC_SIZE_OF(ServoUACacheMallocSizeOf)
MOZ_DEFINE_MALLOC_ENCLOSING_SIZE_OF(ServoUACacheMallocEnclosingSizeOf)

NS_IMETHODIMP
UACacheReporter::CollectReports(nsIHandleReportCallback* aHandleReport,
                                nsISupports* aData, bool aAnonymize)
{
  ServoStyleSetSizes sizes;
  Servo_UACache_AddSizeOf(ServoUACacheMallocSizeOf,
                          ServoUACacheMallocEnclosingSizeOf, &sizes);

#define REPORT(_path, _amount, _desc) \
  do { \
    size_t __amount = _amount;  /* evaluate _amount only once */ \
    if (__amount > 0) { \
      MOZ_COLLECT_REPORT(_path, KIND_HEAP, UNITS_BYTES, __amount, _desc); \
    } \
  } while (0)

  // The UA cache does not contain the rule tree; that's in the StyleSet.
  MOZ_RELEASE_ASSERT(sizes.mRuleTree == 0);

  REPORT("explicit/layout/servo-ua-cache/precomputed-pseudos",
         sizes.mPrecomputedPseudos,
         "Memory used by precomputed pseudo-element declarations within the "
         "UA cache.");

  REPORT("explicit/layout/servo-ua-cache/element-and-pseudos-maps",
         sizes.mElementAndPseudosMaps,
         "Memory used by element and pseudos maps within the UA cache.");

  REPORT("explicit/layout/servo-ua-cache/invalidation-map",
         sizes.mInvalidationMap,
         "Memory used by invalidation maps within the UA cache.");

  REPORT("explicit/layout/servo-ua-cache/revalidation-selectors",
         sizes.mRevalidationSelectors,
         "Memory used by selectors for cache revalidation within the UA "
         "cache.");

  REPORT("explicit/layout/servo-ua-cache/other",
         sizes.mOther,
         "Memory used by other data within the UA cache");

  return NS_OK;
}