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/* -*- 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 */
#ifndef mozilla_StyleSheet_h
#define mozilla_StyleSheet_h
#include "mozilla/Assertions.h"
#include "mozilla/css/SheetParsingMode.h"
#include "mozilla/dom/CSSStyleSheetBinding.h"
#include "mozilla/dom/SRIMetadata.h"
#include "mozilla/CORSMode.h"
#include "mozilla/MozPromise.h"
#include "mozilla/RefPtr.h"
#include "mozilla/ServoBindingTypes.h"
#include "mozilla/ServoTypes.h"
#include "mozilla/StaticPrefs_network.h"
#include "mozilla/StyleSheetInfo.h"
#include "nsICSSLoaderObserver.h"
#include "nsIPrincipal.h"
#include "nsWrapperCache.h"
#include "nsStringFwd.h"
#include "nsProxyRelease.h"
class nsIGlobalObject;
class nsINode;
class nsIPrincipal;
struct StyleLockedCssRules;
class nsIReferrerInfo;
namespace mozilla {
class ServoCSSRuleList;
class ServoStyleSet;
using StyleSheetParsePromise = MozPromise</* Dummy */ bool,
/* Dummy */ bool,
/* IsExclusive = */ true>;
enum class StyleRuleChangeKind : uint32_t;
namespace css {
class GroupRule;
class Loader;
class LoaderReusableStyleSheets;
class Rule;
class SheetLoadData;
using SheetLoadDataHolder = nsMainThreadPtrHolder<SheetLoadData>;
} // namespace css
namespace dom {
class CSSImportRule;
class CSSRuleList;
class DocumentOrShadowRoot;
class MediaList;
class ShadowRoot;
struct CSSStyleSheetInit;
} // namespace dom
enum class StyleSheetState : uint8_t {
// Whether the sheet is disabled. Sheets can be made disabled via CSSOM, or
// via alternate links and such.
Disabled = 1 << 0,
// Whether the sheet is complete. The sheet is complete if it's finished
// loading. See StyleSheet::SetComplete.
Complete = 1 << 1,
// Whether we've forced a unique inner. StyleSheet objects share an 'inner'
// StyleSheetInfo object if they share URL, CORS mode, etc.
// See the Loader's `mCompleteSheets` and `mLoadingSheets`.
ForcedUniqueInner = 1 << 2,
// Whether this stylesheet has suffered any modification to the rules via
ModifiedRules = 1 << 3,
// Same flag, but devtools clears it in some specific situations.
// Used to control whether devtools shows the rule in its authored form or
// not.
ModifiedRulesForDevtools = 1 << 4,
// Whether modifications to the sheet are currently disallowed.
// This flag is set during the async Replace() function to ensure
// that the sheet is not modified until the promise is resolved.
ModificationDisallowed = 1 << 5,
class StyleSheet final : public nsICSSLoaderObserver, public nsWrapperCache {
StyleSheet(const StyleSheet& aCopy, StyleSheet* aParentSheetToUse,
dom::DocumentOrShadowRoot* aDocOrShadowRootToUse,
dom::Document* aConstructorDocToUse);
virtual ~StyleSheet();
using State = StyleSheetState;
StyleSheet(css::SheetParsingMode aParsingMode, CORSMode aCORSMode,
const dom::SRIMetadata& aIntegrity);
static already_AddRefed<StyleSheet> Constructor(const dom::GlobalObject&,
const dom::CSSStyleSheetInit&,
already_AddRefed<StyleSheet> CreateEmptyChildSheet(
already_AddRefed<dom::MediaList> aMediaList) const;
bool HasRules() const;
// Parses a stylesheet. The load data argument corresponds to the
// SheetLoadData for this stylesheet.
// NOTE: ParseSheet can run synchronously or asynchronously
// based on the result of `AllowParallelParse`
RefPtr<StyleSheetParsePromise> ParseSheet(
css::Loader&, const nsACString& aBytes,
const RefPtr<css::SheetLoadDataHolder>& aLoadData);
// Common code that needs to be called after servo finishes parsing. This is
// shared between the parallel and sequential paths.
void FinishAsyncParse(already_AddRefed<StyleStylesheetContents>,
// Similar to `ParseSheet`, but guarantees that
// parsing will be performed synchronously.
// NOTE: ParseSheet can still run synchronously.
// This is not a strict alternative.
// The load data may be null sometimes.
void ParseSheetSync(
css::Loader* aLoader, const nsACString& aBytes,
css::SheetLoadData* aLoadData,
css::LoaderReusableStyleSheets* aReusableSheets = nullptr);
void ReparseSheet(const nsACString& aInput, ErrorResult& aRv);
const StyleStylesheetContents* RawContents() const {
return Inner().mContents;
const StyleUseCounters* GetStyleUseCounters() const {
return Inner().mUseCounters.get();
URLExtraData* URLData() const { return Inner().mURLData; }
// nsICSSLoaderObserver interface
NS_IMETHOD StyleSheetLoaded(StyleSheet* aSheet, bool aWasDeferred,
nsresult aStatus) final;
// Internal GetCssRules methods which do not have security check and
// completeness check.
ServoCSSRuleList* GetCssRulesInternal();
// Returns the stylesheet's Servo origin as a StyleOrigin value.
StyleOrigin GetOrigin() const;
void SetOwningNode(nsINode* aOwningNode) { mOwningNode = aOwningNode; }
css::SheetParsingMode ParsingMode() const { return mParsingMode; }
dom::CSSStyleSheetParsingMode ParsingModeDOM();
* Whether the sheet is complete.
bool IsComplete() const { return bool(mState & State::Complete); }
void SetComplete();
void SetEnabled(bool aEnabled) { SetDisabled(!aEnabled); }
// Whether the sheet is for an inline <style> element.
bool IsInline() const { return !GetOriginalURI(); }
nsIURI* GetSheetURI() const { return Inner().mSheetURI; }
* Get the URI this sheet was originally loaded from, if any. Can return null.
nsIURI* GetOriginalURI() const { return Inner().mOriginalSheetURI; }
nsIURI* GetBaseURI() const { return Inner().mBaseURI; }
* SetURIs must be called on all sheets before parsing into them.
* SetURIs may only be called while the sheet is 1) incomplete and 2)
* has no rules in it.
* FIXME(emilio): Can we pass this down when constructing the sheet instead?
inline void SetURIs(nsIURI* aSheetURI, nsIURI* aOriginalSheetURI,
nsIURI* aBaseURI);
* Whether the sheet is applicable. A sheet that is not applicable
* should never be inserted into a style set. A sheet may not be
* applicable for a variety of reasons including being disabled and
* being incomplete.
bool IsApplicable() const { return !Disabled() && IsComplete(); }
already_AddRefed<StyleSheet> Clone(
StyleSheet* aCloneParent,
dom::DocumentOrShadowRoot* aCloneDocumentOrShadowRoot) const;
* Creates a clone of the adopted style sheet as though it were constructed
* by aConstructorDocument. This should only be used for printing.
already_AddRefed<StyleSheet> CloneAdoptedSheet(
dom::Document& aConstructorDocument) const;
bool HasForcedUniqueInner() const {
return bool(mState & State::ForcedUniqueInner);
bool HasModifiedRules() const { return bool(mState & State::ModifiedRules); }
bool HasModifiedRulesForDevtools() const {
return bool(mState & State::ModifiedRulesForDevtools);
bool HasUniqueInner() const { return Inner().mSheets.Length() == 1; }
void AssertHasUniqueInner() const { MOZ_ASSERT(HasUniqueInner()); }
void EnsureUniqueInner();
// Returns the DocumentOrShadowRoot* that owns us, if any.
// TODO(emilio): Maybe rename to GetOwner*() or such? Might be
// confusing with nsINode::OwnerDoc and such.
dom::DocumentOrShadowRoot* GetAssociatedDocumentOrShadowRoot() const;
// Whether this stylesheet is kept alive by the associated or constructor
// document somehow, and thus at least has the same lifetime as
// GetAssociatedDocument().
dom::Document* GetKeptAliveByDocument() const;
// If this is a constructed style sheet, return mConstructorDocument.
// Otherwise return the document we're associated to,
// via mDocumentOrShadowRoot.
// Non-null iff GetAssociatedDocumentOrShadowRoot is non-null.
dom::Document* GetAssociatedDocument() const;
void SetAssociatedDocumentOrShadowRoot(dom::DocumentOrShadowRoot*);
void ClearAssociatedDocumentOrShadowRoot() {
nsINode* GetOwnerNode() const { return mOwningNode; }
nsINode* GetOwnerNodeOfOutermostSheet() const {
return OutermostSheet().GetOwnerNode();
StyleSheet* GetParentSheet() const { return mParentSheet; }
void AddReferencingRule(dom::CSSImportRule& aRule) {
void RemoveReferencingRule(dom::CSSImportRule& aRule) {
// Note that when exposed to script, this should always have a <= 1 length.
// CSSImportRule::GetStyleSheetForBindings takes care of that.
dom::CSSImportRule* GetOwnerRule() const {
return mReferencingRules.SafeElementAt(0);
void AppendStyleSheet(StyleSheet&);
// Append a stylesheet to the child list without calling WillDirty.
void AppendStyleSheetSilently(StyleSheet&);
const nsTArray<RefPtr<StyleSheet>>& ChildSheets() const {
#ifdef DEBUG
for (StyleSheet* child : Inner().mChildren) {
MOZ_ASSERT(child->GetParentSheet()->mInner == mInner);
return Inner().mChildren;
// Principal() never returns a null pointer.
nsIPrincipal* Principal() const { return Inner().mPrincipal; }
* SetPrincipal should be called on all sheets before parsing into them.
* This can only be called once with a non-null principal.
* Calling this with a null pointer is allowed and is treated as a no-op.
* FIXME(emilio): Can we get this at construction time instead?
void SetPrincipal(nsIPrincipal* aPrincipal) {
StyleSheetInfo& info = Inner();
MOZ_ASSERT_IF(info.mPrincipalSet, info.mPrincipal == aPrincipal);
if (aPrincipal) {
info.mPrincipal = aPrincipal;
#ifdef DEBUG
info.mPrincipalSet = true;
void SetTitle(const nsAString& aTitle) { mTitle = aTitle; }
void SetMedia(already_AddRefed<dom::MediaList> aMedia);
// Get this style sheet's CORS mode
CORSMode GetCORSMode() const { return Inner().mCORSMode; }
// Get this style sheet's ReferrerInfo
nsIReferrerInfo* GetReferrerInfo() const { return Inner().mReferrerInfo; }
// Set this style sheet's ReferrerInfo
void SetReferrerInfo(nsIReferrerInfo* aReferrerInfo) {
Inner().mReferrerInfo = aReferrerInfo;
// Get this style sheet's integrity metadata
void GetIntegrity(dom::SRIMetadata& aResult) const {
aResult = Inner().mIntegrity;
size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const;
#if defined(DEBUG) || defined(MOZ_LAYOUT_DEBUGGER)
void List(FILE* aOut = stdout, int32_t aIndex = 0);
// WebIDL StyleSheet API
void GetType(nsAString& aType);
void GetHref(nsAString& aHref, ErrorResult& aRv);
// GetOwnerNode is defined above.
StyleSheet* GetParentStyleSheet() const { return GetParentSheet(); }
void GetTitle(nsAString& aTitle);
dom::MediaList* Media();
bool Disabled() const { return bool(mState & State::Disabled); }
void SetDisabled(bool aDisabled);
void GetSourceMapURL(nsACString&);
void SetSourceMapURL(nsCString&&);
void GetSourceURL(nsACString& aSourceURL);
// WebIDL CSSStyleSheet API
// Can't be inline because we can't include ImportRule here. And can't be
// called GetOwnerRule because that would be ambiguous with the ImportRule
// version.
css::Rule* GetDOMOwnerRule() const;
dom::CSSRuleList* GetCssRules(nsIPrincipal& aSubjectPrincipal, ErrorResult&);
uint32_t InsertRule(const nsACString& aRule, uint32_t aIndex,
nsIPrincipal& aSubjectPrincipal, ErrorResult& aRv);
void DeleteRule(uint32_t aIndex, nsIPrincipal& aSubjectPrincipal,
ErrorResult& aRv);
int32_t AddRule(const nsACString& aSelector, const nsACString& aBlock,
const dom::Optional<uint32_t>& aIndex,
nsIPrincipal& aSubjectPrincipal, ErrorResult& aRv);
already_AddRefed<dom::Promise> Replace(const nsACString& aText, ErrorResult&);
void ReplaceSync(const nsACString& aText, ErrorResult&);
bool ModificationDisallowed() const {
return bool(mState & State::ModificationDisallowed);
// Called before and after the asynchronous Replace() function
// to disable/re-enable modification while there is a pending promise.
void SetModificationDisallowed(bool aDisallowed) {
if (aDisallowed) {
mState |= State::ModificationDisallowed;
// Sheet will be re-set to complete when its rules are replaced
mState &= ~State::Complete;
if (!Disabled()) {
} else {
mState &= ~State::ModificationDisallowed;
// True if the sheet was created through the Constructable StyleSheets API
bool IsConstructed() const { return !!mConstructorDocument; }
// True if any of this sheet's ancestors were created through the
// Constructable StyleSheets API
bool SelfOrAncestorIsConstructed() const {
return OutermostSheet().IsConstructed();
// Ture if the sheet's constructor document matches the given document
bool ConstructorDocumentMatches(const dom::Document& aDocument) const {
return mConstructorDocument == &aDocument;
// Add a document or shadow root to the list of adopters.
// Adopters will be notified when styles are changed.
void AddAdopter(dom::DocumentOrShadowRoot& aAdopter) {
// Remove a document or shadow root from the list of adopters.
void RemoveAdopter(dom::DocumentOrShadowRoot& aAdopter) {
// Cannot assert IsConstructed() because this can run after unlink.
const nsTArray<dom::DocumentOrShadowRoot*>& SelfOrAncestorAdopters() const {
return OutermostSheet().mAdopters;
// WebIDL miscellaneous bits
inline dom::ParentObject GetParentObject() const;
JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) final;
// Changes to sheets should be after a WillDirty call.
void WillDirty();
// Called when a rule changes from CSSOM.
// FIXME(emilio): This shouldn't allow null, but MediaList doesn't know about
// its owning media rule, plus it's used for the stylesheet media itself.
void RuleChanged(css::Rule*, StyleRuleChangeKind);
void AddStyleSet(ServoStyleSet* aStyleSet);
void DropStyleSet(ServoStyleSet* aStyleSet);
nsresult DeleteRuleFromGroup(css::GroupRule* aGroup, uint32_t aIndex);
nsresult InsertRuleIntoGroup(const nsACString& aRule, css::GroupRule* aGroup,
uint32_t aIndex);
// Find the ID of the owner inner window.
uint64_t FindOwningWindowInnerID() const;
// Copy the contents of this style sheet into the shared memory buffer managed
// by aBuilder. Returns the pointer into the buffer that the sheet contents
// were stored at. (The returned pointer is to an Arc<Locked<Rules>> value,
// or null, with a filled in aErrorMessage, on failure.)
const StyleLockedCssRules* ToShared(StyleSharedMemoryBuilder* aBuilder,
nsCString& aErrorMessage);
// Sets the contents of this style sheet to the specified aSharedRules
// pointer, which must be a pointer somewhere in the aSharedMemory buffer
// as previously returned by a ToShared() call.
void SetSharedContents(const StyleLockedCssRules* aSharedRules);
// Whether this style sheet should not allow any modifications.
// This is true for any User Agent sheets once they are complete.
bool IsReadOnly() const;
// Removes a stylesheet from its parent sheet child list, if any.
void RemoveFromParent();
// Resolves mReplacePromise with this sheet.
void MaybeResolveReplacePromise();
// Rejects mReplacePromise with a NetworkError.
void MaybeRejectReplacePromise();
// Gets the relevant global if exists.
nsISupports* GetRelevantGlobal() const;
// Blocks/Unblocks resolution of parse promise
void BlockParsePromise() {
uint32_t count =
void UnblockParsePromise() {
uint32_t count = --mAsyncParseBlockers;
if (!count && !mParsePromise.IsEmpty()) {
mParsePromise.Resolve(true, __func__);
void SetModifiedRules() {
mState |= State::ModifiedRules | State::ModifiedRulesForDevtools;
const StyleSheet& OutermostSheet() const {
const auto* current = this;
while (current->mParentSheet) {
"Shouldn't be set on child sheets");
"Shouldn't be set on child sheets");
current = current->mParentSheet;
return *current;
StyleSheetInfo& Inner() {
return *mInner;
const StyleSheetInfo& Inner() const {
return *mInner;
// Check if the rules are available for read and write.
// It does the security check as well as whether the rules have been
// completely loaded. aRv will have an exception set if this function
// returns false.
bool AreRulesAvailable(nsIPrincipal& aSubjectPrincipal, ErrorResult& aRv);
void SetURLExtraData();
// Internal methods which do not have security check and completeness check.
uint32_t InsertRuleInternal(const nsACString& aRule, uint32_t aIndex,
void DeleteRuleInternal(uint32_t aIndex, ErrorResult&);
nsresult InsertRuleIntoGroupInternal(const nsACString& aRule,
css::GroupRule* aGroup, uint32_t aIndex);
// Take the recently cloned sheets from the `@import` rules, and reparent them
// correctly to `aPrimarySheet`.
void FixUpAfterInnerClone();
// aFromClone says whether this comes from a clone of the stylesheet (and thus
// we should also fix up the wrappers for the individual rules in the rule
// lists).
void FixUpRuleListAfterContentsChangeIfNeeded(bool aFromClone = false);
void DropRuleList();
// Called when a rule is removed from the sheet from CSSOM.
void RuleAdded(css::Rule&);
// Called when a rule is added to the sheet from CSSOM.
void RuleRemoved(css::Rule&);
// Called when a stylesheet is cloned.
void StyleSheetCloned(StyleSheet&);
// Notifies that the applicable state changed.
// aApplicable is the value that we expect to get from IsApplicable().
// assertion will fail if the expectation does not match reality.
void ApplicableStateChanged(bool aApplicable);
void LastRelease();
// Return success if the subject principal subsumes the principal of our
// inner, error otherwise. This will also succeed if access is allowed by
// CORS. In that case, it will set the principal of the inner to the
// subject principal.
void SubjectSubsumesInnerPrincipal(nsIPrincipal& aSubjectPrincipal,
ErrorResult& aRv);
// Drop our reference to mMedia
void DropMedia();
// Set our relevant global if needed.
void UpdateRelevantGlobal();
// Unlink our inner, if needed, for cycle collection.
void UnlinkInner();
// Traverse our inner, if needed, for cycle collection
void TraverseInner(nsCycleCollectionTraversalCallback&);
// Return whether the given @import rule has pending child sheet.
static bool RuleHasPendingChildSheet(css::Rule* aRule);
StyleSheet* mParentSheet; // weak ref
// A pointer to the sheet's relevant global object. This is populated when the
// sheet gets an associated document and is complete.
// This is required for the sheet to be able to create a promise.
nsCOMPtr<nsIGlobalObject> mRelevantGlobal;
RefPtr<dom::Document> mConstructorDocument;
// Will be set in the Replace() function and resolved/rejected by the
// sheet once its rules have been replaced and the sheet is complete again.
RefPtr<dom::Promise> mReplacePromise;
nsString mTitle;
// weak ref; parents maintain this for their children
dom::DocumentOrShadowRoot* mDocumentOrShadowRoot;
nsINode* mOwningNode = nullptr; // weak ref
nsTArray<dom::CSSImportRule*> mReferencingRules; // weak ref
RefPtr<dom::MediaList> mMedia;
// mParsingMode controls access to nonstandard style constructs that
// are not safe for use on the public Web but necessary in UA sheets
// and/or useful in user sheets.
// FIXME(emilio): Given we store the parsed contents in the Inner, this should
// probably also move there.
css::SheetParsingMode mParsingMode;
State mState;
Atomic<uint32_t, ReleaseAcquire> mAsyncParseBlockers{0};
// Core information we get from parsed sheets, which are shared amongst
// StyleSheet clones.
// Always nonnull until LastRelease().
StyleSheetInfo* mInner;
nsTArray<ServoStyleSet*> mStyleSets;
RefPtr<ServoCSSRuleList> mRuleList;
MozPromiseHolder<StyleSheetParsePromise> mParsePromise;
nsTArray<dom::DocumentOrShadowRoot*> mAdopters;
// Make StyleSheetInfo and subclasses into friends so they can use
// ChildSheetListBuilder.
friend struct StyleSheetInfo;
} // namespace mozilla
#endif // mozilla_StyleSheet_h