Bug 1729330 - Add a simple CSSLayerRule implementation. r=smaug

The specifics of how this is going to work are still getting spec'd /
discussed in w3c/csswg-drafts#6576, but this
allows DevTools to work fine and the feature to be complete enough for
Nightly experimentation (with the other in-flight patches).

Otherwise devtools crashes when trying to inspect pages that use them.

Differential Revision: https://phabricator.services.mozilla.com/D124656

dom/base/nsAttrValue.cpp

@@ -1739,7 +1739,7 @@ bool nsAttrValue::ParseStyleAttribute(const nsAString& aString,
   auto data = MakeRefPtr<URLExtraData>(baseURI, referrerInfo, principal);
   RefPtr<DeclarationBlock> decl = DeclarationBlock::FromCssText(
       aString, data, ownerDoc->GetCompatibilityMode(), ownerDoc->CSSLoader(),
-      dom::CSSRule_Binding::STYLE_RULE);
+      StyleCssRuleType::Style);
   if (!decl) {
     return false;
   }

dom/svg/SVGElement.cpp

@@ -1217,7 +1217,7 @@ void MappedAttrParser::ParseMappedAttrValue(nsAtom* aMappedAttrName,
         mDecl->Raw(), propertyID, &value, false, data,
         ParsingMode::AllowUnitlessLength,
         mElement->OwnerDoc()->GetCompatibilityMode(), mLoader,
-        CSSRule_Binding::STYLE_RULE, {});
+        StyleCssRuleType::Style, {});
 
     // TODO(emilio): If we want to record these from CSSOM more generally, we
     // can pass the document use counters down the FFI call. For now manually

dom/webidl/CSSGroupingRule.webidl

@@ -10,7 +10,7 @@
 // https://drafts.csswg.org/cssom/#cssgroupingrule
 [Exposed=Window]
 interface CSSGroupingRule : CSSRule {
-  [SameObject] readonly attribute CSSRuleList cssRules;
+  [SameObject] readonly attribute CSSRuleList? cssRules;
   [Throws]
   unsigned long insertRule(UTF8String rule, optional unsigned long index = 0);
   [Throws]

dom/webidl/CSSLayerRule.webidl

@@ -0,0 +1,12 @@
+/* -*- Mode: IDL; 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/.
+ *
+ * This is just scaffolding waiting for
+ * https://github.com/w3c/csswg-drafts/issues/6576 to get resolved.
+ */
+
+[Exposed=Window, Pref="layout.css.cascade-layers.enabled"]
+interface CSSLayerRule : CSSGroupingRule {
+};

dom/webidl/CSSRule.webidl

@@ -25,7 +25,7 @@ interface CSSRule {
   // XXXbz Should we expose the constant anyway?
   // const unsigned short MARGIN_RULE = 9;
   const unsigned short NAMESPACE_RULE = 10;
-  readonly attribute unsigned short type;
+  [BinaryName="typeForBindings"] readonly attribute unsigned short type;
   attribute UTF8String cssText;
   readonly attribute CSSRule? parentRule;
   readonly attribute CSSStyleSheet? parentStyleSheet;

dom/webidl/moz.build

@@ -477,6 +477,7 @@ WEBIDL_FILES = [
     "CSSImportRule.webidl",
     "CSSKeyframeRule.webidl",
     "CSSKeyframesRule.webidl",
+    "CSSLayerRule.webidl",
     "CSSMediaRule.webidl",
     "CSSMozDocumentRule.webidl",
     "CSSNamespaceRule.webidl",

dom/xul/nsXULElement.cpp

@@ -1542,7 +1542,7 @@ nsresult nsXULPrototypeElement::SetAttrAt(uint32_t aPos,
     auto data = MakeRefPtr<URLExtraData>(aDocumentURI, referrerInfo, principal);
     RefPtr<DeclarationBlock> declaration = DeclarationBlock::FromCssText(
         aValue, data, eCompatibility_FullStandards, nullptr,
-        CSSRule_Binding::STYLE_RULE);
+        StyleCssRuleType::Style);
     if (declaration) {
       mAttributes[aPos].mValue.SetTo(declaration.forget(), &aValue);
 

layout/inspector/ServoStyleRuleMap.cpp

@@ -77,29 +77,29 @@ void ServoStyleRuleMap::RuleRemoved(StyleSheet& aStyleSheet,
   }
 
   switch (aStyleRule.Type()) {
-    case CSSRule_Binding::STYLE_RULE: {
+    case StyleCssRuleType::Style: {
       auto& rule = static_cast<CSSStyleRule&>(aStyleRule);
       mTable.Remove(rule.Raw());
       break;
     }
-    case CSSRule_Binding::IMPORT_RULE:
-    case CSSRule_Binding::MEDIA_RULE:
-    case CSSRule_Binding::SUPPORTS_RULE:
-    case CSSRule_Binding::DOCUMENT_RULE: {
+    case StyleCssRuleType::Import:
+    case StyleCssRuleType::Media:
+    case StyleCssRuleType::Supports:
+    case StyleCssRuleType::Layer:
+    case StyleCssRuleType::Document: {
       // See the comment in StyleSheetRemoved.
       mTable.Clear();
       break;
     }
-    case CSSRule_Binding::FONT_FACE_RULE:
-    case CSSRule_Binding::PAGE_RULE:
-    case CSSRule_Binding::KEYFRAMES_RULE:
-    case CSSRule_Binding::KEYFRAME_RULE:
-    case CSSRule_Binding::NAMESPACE_RULE:
-    case CSSRule_Binding::COUNTER_STYLE_RULE:
-    case CSSRule_Binding::FONT_FEATURE_VALUES_RULE:
+    case StyleCssRuleType::FontFace:
+    case StyleCssRuleType::Page:
+    case StyleCssRuleType::Keyframes:
+    case StyleCssRuleType::Keyframe:
+    case StyleCssRuleType::Namespace:
+    case StyleCssRuleType::CounterStyle:
+    case StyleCssRuleType::FontFeatureValues:
+    case StyleCssRuleType::Viewport:
       break;
-    default:
-      MOZ_ASSERT_UNREACHABLE("Unhandled rule");
   }
 }
 
@@ -112,25 +112,36 @@ size_t ServoStyleRuleMap::SizeOfIncludingThis(
 
 void ServoStyleRuleMap::FillTableFromRule(css::Rule& aRule) {
   switch (aRule.Type()) {
-    case CSSRule_Binding::STYLE_RULE: {
+    case StyleCssRuleType::Style: {
       auto& rule = static_cast<CSSStyleRule&>(aRule);
       mTable.InsertOrUpdate(rule.Raw(), &rule);
       break;
     }
-    case CSSRule_Binding::MEDIA_RULE:
-    case CSSRule_Binding::SUPPORTS_RULE:
-    case CSSRule_Binding::DOCUMENT_RULE: {
+    case StyleCssRuleType::Layer:
+    case StyleCssRuleType::Media:
+    case StyleCssRuleType::Supports:
+    case StyleCssRuleType::Document: {
       auto& rule = static_cast<css::GroupRule&>(aRule);
-      auto ruleList = static_cast<ServoCSSRuleList*>(rule.CssRules());
-      FillTableFromRuleList(*ruleList);
+      if (ServoCSSRuleList* ruleList = rule.GetCssRules()) {
+        FillTableFromRuleList(*ruleList);
+      }
       break;
     }
-    case CSSRule_Binding::IMPORT_RULE: {
+    case StyleCssRuleType::Import: {
       auto& rule = static_cast<CSSImportRule&>(aRule);
       MOZ_ASSERT(aRule.GetStyleSheet());
       FillTableFromStyleSheet(*rule.GetStyleSheet());
       break;
     }
+    case StyleCssRuleType::FontFace:
+    case StyleCssRuleType::Page:
+    case StyleCssRuleType::Keyframes:
+    case StyleCssRuleType::Keyframe:
+    case StyleCssRuleType::Namespace:
+    case StyleCssRuleType::CounterStyle:
+    case StyleCssRuleType::FontFeatureValues:
+    case StyleCssRuleType::Viewport:
+      break;
   }
 }
 

layout/style/CSSCounterStyleRule.cpp

@@ -27,8 +27,8 @@ void CSSCounterStyleRule::List(FILE* out, int32_t aIndent) const {
 }
 #endif
 
-uint16_t CSSCounterStyleRule::Type() const {
-  return CSSRule_Binding::COUNTER_STYLE_RULE;
+StyleCssRuleType CSSCounterStyleRule::Type() const {
+  return StyleCssRuleType::CounterStyle;
 }
 
 void CSSCounterStyleRule::SetRawAfterClone(

layout/style/CSSCounterStyleRule.h

@@ -12,8 +12,7 @@
 
 struct RawServoCounterStyleRule;
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 class CSSCounterStyleRule final : public css::Rule {
  public:
@@ -41,7 +40,7 @@ class CSSCounterStyleRule final : public css::Rule {
 #endif
 
   // WebIDL interface
-  uint16_t Type() const override;
+  StyleCssRuleType Type() const override;
   void GetCssText(nsACString& aCssText) const override;
   void GetName(nsAString& aName);
   void SetName(const nsAString& aName);
@@ -59,7 +58,6 @@ class CSSCounterStyleRule final : public css::Rule {
   RefPtr<RawServoCounterStyleRule> mRawRule;
 };
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
 
 #endif  // mozilla_CSSCounterStyleRule_h

layout/style/CSSFontFaceRule.cpp

@@ -197,8 +197,8 @@ void CSSFontFaceRule::List(FILE* out, int32_t aIndent) const {
 }
 #endif
 
-uint16_t CSSFontFaceRule::Type() const {
-  return CSSRule_Binding::FONT_FACE_RULE;
+StyleCssRuleType CSSFontFaceRule::Type() const {
+  return StyleCssRuleType::FontFace;
 }
 
 void CSSFontFaceRule::SetRawAfterClone(RefPtr<RawServoFontFaceRule> aRaw) {

layout/style/CSSFontFaceRule.h

@@ -11,8 +11,7 @@
 #include "mozilla/css/Rule.h"
 #include "nsICSSDeclaration.h"
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 // A CSSFontFaceRuleDecl is always embeded in a CSSFontFaceRule.
 class CSSFontFaceRule;
@@ -68,7 +67,7 @@ class CSSFontFaceRule final : public css::Rule {
   void SetRawAfterClone(RefPtr<RawServoFontFaceRule>);
 
   // WebIDL interface
-  uint16_t Type() const final;
+  StyleCssRuleType Type() const final;
   void GetCssText(nsACString& aCssText) const final;
   nsICSSDeclaration* Style();
 
@@ -100,7 +99,6 @@ inline const CSSFontFaceRule* CSSFontFaceRuleDecl::ContainingRule() const {
       reinterpret_cast<const char*>(this) - offsetof(CSSFontFaceRule, mDecl));
 }
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
 
 #endif  // mozilla_CSSFontFaceRule_h

layout/style/CSSFontFeatureValuesRule.cpp

@@ -8,15 +8,18 @@
 #include "mozilla/dom/CSSFontFeatureValuesRuleBinding.h"
 #include "mozilla/ServoBindings.h"
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 size_t CSSFontFeatureValuesRule::SizeOfIncludingThis(
     MallocSizeOf aMallocSizeOf) const {
   // TODO Implement this!
   return aMallocSizeOf(this);
 }
 
+StyleCssRuleType CSSFontFeatureValuesRule::Type() const {
+  return StyleCssRuleType::FontFeatureValues;
+}
+
 #ifdef DEBUG
 void CSSFontFeatureValuesRule::List(FILE* out, int32_t aIndent) const {
   nsAutoCString str;
@@ -78,5 +81,4 @@ JSObject* CSSFontFeatureValuesRule::WrapObject(
   return CSSFontFeatureValuesRule_Binding::Wrap(aCx, this, aGivenProto);
 }
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom

layout/style/CSSFontFeatureValuesRule.h

@@ -12,8 +12,7 @@
 
 #include "nsICSSDeclaration.h"
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 class CSSFontFeatureValuesRule final : public css::Rule {
  public:
@@ -29,9 +28,7 @@ class CSSFontFeatureValuesRule final : public css::Rule {
   void SetRawAfterClone(RefPtr<RawServoFontFeatureValuesRule> aRaw);
 
   // WebIDL interfaces
-  uint16_t Type() const final {
-    return CSSRule_Binding::FONT_FEATURE_VALUES_RULE;
-  }
+  StyleCssRuleType Type() const final;
 
   void GetCssText(nsACString& aCssText) const override;
   void GetFontFamily(nsACString& aFamily);
@@ -55,7 +52,6 @@ class CSSFontFeatureValuesRule final : public css::Rule {
   RefPtr<RawServoFontFeatureValuesRule> mRawRule;
 };
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
 
 #endif  // mozilla_dom_CSSFontFeatureValuesRule_h

layout/style/CSSImportRule.cpp

@@ -73,6 +73,10 @@ void CSSImportRule::List(FILE* out, int32_t aIndent) const {
 }
 #endif
 
+StyleCssRuleType CSSImportRule::Type() const {
+  return StyleCssRuleType::Import;
+}
+
 void CSSImportRule::SetRawAfterClone(RefPtr<RawServoImportRule> aRaw) {
   mRawRule = std::move(aRaw);
   if (mChildSheet) {

layout/style/CSSImportRule.h

@@ -32,7 +32,7 @@ class CSSImportRule final : public css::Rule {
   size_t SizeOfIncludingThis(MallocSizeOf) const override;
 
   // WebIDL interface
-  uint16_t Type() const final { return CSSRule_Binding::IMPORT_RULE; }
+  StyleCssRuleType Type() const final;
   void GetCssText(nsACString& aCssText) const override;
   void GetHref(nsAString& aHref) const;
   dom::MediaList* GetMedia();

layout/style/CSSKeyframeRule.cpp

@@ -10,8 +10,7 @@
 #include "mozilla/dom/CSSKeyframeRuleBinding.h"
 #include "nsDOMCSSDeclaration.h"
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 // -------------------------------------------
 // CSSKeyframeDeclaration
@@ -62,7 +61,7 @@ class CSSKeyframeDeclaration : public nsDOMCSSDeclaration {
   }
   ParsingEnvironment GetParsingEnvironment(
       nsIPrincipal* aSubjectPrincipal) const final {
-    return GetParsingEnvironmentForRule(mRule, CSSRule_Binding::KEYFRAME_RULE);
+    return GetParsingEnvironmentForRule(mRule, StyleCssRuleType::Keyframe);
   }
   Document* DocToUpdate() final { return nullptr; }
 
@@ -142,6 +141,10 @@ bool CSSKeyframeRule::IsCCLeaf() const {
   return Rule::IsCCLeaf() && !mDeclaration;
 }
 
+StyleCssRuleType CSSKeyframeRule::Type() const {
+  return StyleCssRuleType::Keyframe;
+}
+
 void CSSKeyframeRule::SetRawAfterClone(RefPtr<RawServoKeyframe> aRaw) {
   mRaw = std::move(aRaw);
 
@@ -214,5 +217,4 @@ JSObject* CSSKeyframeRule::WrapObject(JSContext* aCx,
   return CSSKeyframeRule_Binding::Wrap(aCx, this, aGivenProto);
 }
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom

layout/style/CSSKeyframeRule.h

@@ -11,10 +11,8 @@
 #include "mozilla/ServoBindingTypes.h"
 
 class nsICSSDeclaration;
-class DeclarationBlock;
 
-namespace mozilla {
-namespace dom {
+namespace mozilla::dom {
 
 class CSSKeyframeDeclaration;
 
@@ -35,7 +33,7 @@ class CSSKeyframeRule final : public css::Rule {
   void SetRawAfterClone(RefPtr<RawServoKeyframe>);
 
   // WebIDL interface
-  uint16_t Type() const final { return CSSRule_Binding::KEYFRAME_RULE; }
+  StyleCssRuleType Type() const final;
   void GetCssText(nsACString& aCssText) const final;
   void GetKeyText(nsACString& aKey);
   void SetKeyText(const nsACString& aKey);
@@ -58,7 +56,6 @@ class CSSKeyframeRule final : public css::Rule {
   RefPtr<CSSKeyframeDeclaration> mDeclaration;
 };
 
-}  // namespace dom
-}  // namespace mozilla
+}  // namespace mozilla::dom
 
 #endif  // mozilla_dom_CSSKeyframeRule_h