Bug 1882581: Implement @scope parsing. r=firefox-style-system-revie…

…wers,saschanaz,emilio

Differential Revision: https://phabricator.services.mozilla.com/D203153

dom/webidl/CSSScopeRule.webidl

@@ -0,0 +1,14 @@
+/* -*- 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/.
+ *
+ * The origin of this IDL file is
+ * https://drafts.csswg.org/css-cascade-6/#the-cssscoperule-interface
+ */
+
+[Exposed=Window, Pref="layout.css.at-scope.enabled"]
+interface CSSScopeRule : CSSGroupingRule {
+  readonly attribute UTF8String? start;
+  readonly attribute UTF8String? end;
+};

dom/webidl/moz.build

@@ -492,6 +492,7 @@ WEBIDL_FILES = [
     "CSSPseudoElement.webidl",
     "CSSRule.webidl",
     "CSSRuleList.webidl",
+    "CSSScopeRule.webidl",
     "CSSStyleDeclaration.webidl",
     "CSSStyleRule.webidl",
     "CSSStyleSheet.webidl",

layout/inspector/InspectorUtils.cpp

@@ -433,6 +433,7 @@ static uint32_t CollectAtRules(ServoCSSRuleList& aRuleList,
       case StyleCssRuleType::CounterStyle:
       case StyleCssRuleType::FontFeatureValues:
       case StyleCssRuleType::FontPaletteValues:
+      case StyleCssRuleType::Scope:
         break;
     }
 

layout/inspector/ServoStyleRuleMap.cpp

@@ -86,7 +86,8 @@ void ServoStyleRuleMap::RuleRemoved(StyleSheet& aStyleSheet,
     case StyleCssRuleType::Supports:
     case StyleCssRuleType::LayerBlock:
     case StyleCssRuleType::Container:
-    case StyleCssRuleType::Document: {
+    case StyleCssRuleType::Document:
+    case StyleCssRuleType::Scope: {
       // See the comment in SheetRemoved.
       mTable.Clear();
       break;
@@ -124,7 +125,8 @@ void ServoStyleRuleMap::FillTableFromRule(css::Rule& aRule) {
     case StyleCssRuleType::Media:
     case StyleCssRuleType::Supports:
     case StyleCssRuleType::Container:
-    case StyleCssRuleType::Document: {
+    case StyleCssRuleType::Document:
+    case StyleCssRuleType::Scope: {
       auto& rule = static_cast<css::GroupRule&>(aRule);
       FillTableFromRuleList(*rule.CssRules());
       break;

layout/style/CSSScopeRule.cpp

@@ -0,0 +1,66 @@
+/* -*- 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/dom/CSSScopeRule.h"
+#include "mozilla/dom/CSSScopeRuleBinding.h"
+#include "mozilla/ServoBindings.h"
+
+namespace mozilla::dom {
+
+CSSScopeRule::CSSScopeRule(RefPtr<StyleScopeRule> aRawRule, StyleSheet* aSheet,
+                           css::Rule* aParentRule, uint32_t aLine,
+                           uint32_t aColumn)
+    : css::GroupRule(aSheet, aParentRule, aLine, aColumn),
+      mRawRule(std::move(aRawRule)) {}
+
+NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED_0(CSSScopeRule, css::GroupRule)
+
+// QueryInterface implementation for SupportsRule
+
+#ifdef DEBUG
+void CSSScopeRule::List(FILE* out, int32_t aIndent) const {
+  nsAutoCString str;
+  for (int32_t i = 0; i < aIndent; i++) {
+    str.AppendLiteral("  ");
+  }
+  Servo_ScopeRule_Debug(mRawRule, &str);
+  fprintf_stderr(out, "%s\n", str.get());
+}
+#endif
+
+StyleCssRuleType CSSScopeRule::Type() const { return StyleCssRuleType::Scope; }
+
+already_AddRefed<StyleLockedCssRules> CSSScopeRule::GetOrCreateRawRules() {
+  return Servo_ScopeRule_GetRules(mRawRule).Consume();
+}
+
+void CSSScopeRule::SetRawAfterClone(RefPtr<StyleScopeRule> aRaw) {
+  mRawRule = std::move(aRaw);
+  css::GroupRule::DidSetRawAfterClone();
+}
+
+void CSSScopeRule::GetCssText(nsACString& aCssText) const {
+  Servo_ScopeRule_GetCssText(mRawRule.get(), &aCssText);
+}
+
+void CSSScopeRule::GetStart(nsACString& aStart) const {
+  Servo_ScopeRule_GetStart(mRawRule.get(), &aStart);
+}
+
+void CSSScopeRule::GetEnd(nsACString& aEnd) const {
+  Servo_ScopeRule_GetEnd(mRawRule.get(), &aEnd);
+}
+
+size_t CSSScopeRule::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const {
+  return aMallocSizeOf(this);
+}
+
+JSObject* CSSScopeRule::WrapObject(JSContext* aCx,
+                                   JS::Handle<JSObject*> aGivenProto) {
+  return CSSScopeRule_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+}  // namespace mozilla::dom

layout/style/CSSScopeRule.h

@@ -0,0 +1,49 @@
+/* -*- 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/. */
+
+#ifndef CSSScopeRule_h___
+#define CSSScopeRule_h___
+
+#include "mozilla/css/GroupRule.h"
+#include "mozilla/ServoBindingTypes.h"
+
+namespace mozilla::dom {
+
+class CSSScopeRule final : public css::GroupRule {
+ public:
+  CSSScopeRule(RefPtr<StyleScopeRule> aRawRule, StyleSheet* aSheet,
+               css::Rule* aParentRule, uint32_t aLine, uint32_t aColumn);
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+#ifdef DEBUG
+  void List(FILE* out = stdout, int32_t aIndent = 0) const final;
+#endif
+
+  StyleScopeRule* Raw() const { return mRawRule; }
+  void SetRawAfterClone(RefPtr<StyleScopeRule>);
+
+  already_AddRefed<StyleLockedCssRules> GetOrCreateRawRules() final;
+
+  // WebIDL interface
+  StyleCssRuleType Type() const final;
+  void GetCssText(nsACString& aCssText) const final;
+
+  void GetStart(nsACString& aStart) const;
+  void GetEnd(nsACString& aEnd) const;
+
+  size_t SizeOfIncludingThis(MallocSizeOf) const override;
+  JSObject* WrapObject(JSContext*, JS::Handle<JSObject*>) override;
+
+ private:
+  ~CSSScopeRule() = default;
+
+  RefPtr<StyleScopeRule> mRawRule;
+};
+
+}  // namespace mozilla::dom
+
+#endif

layout/style/Rule.cpp

@@ -100,13 +100,13 @@ void Rule::AssertParentRuleType() {
   // this->Type() here since it's virtual.
   if (mParentRule) {
     auto type = mParentRule->Type();
-    MOZ_ASSERT(type == StyleCssRuleType::Media ||
-               type == StyleCssRuleType::Style ||
-               type == StyleCssRuleType::Document ||
-               type == StyleCssRuleType::Supports ||
-               type == StyleCssRuleType::Keyframes ||
-               type == StyleCssRuleType::LayerBlock ||
-               type == StyleCssRuleType::Container);
+    MOZ_ASSERT(
+        type == StyleCssRuleType::Media || type == StyleCssRuleType::Style ||
+        type == StyleCssRuleType::Document ||
+        type == StyleCssRuleType::Supports ||
+        type == StyleCssRuleType::Keyframes ||
+        type == StyleCssRuleType::LayerBlock ||
+        type == StyleCssRuleType::Container || type == StyleCssRuleType::Scope);
   }
 }
 #endif

layout/style/ServoBindingTypes.h

@@ -129,6 +129,7 @@ UNLOCKED_RULE_TYPE(Supports)
 UNLOCKED_RULE_TYPE(Document)
 UNLOCKED_RULE_TYPE(FontFeatureValues)
 UNLOCKED_RULE_TYPE(FontPaletteValues)
+UNLOCKED_RULE_TYPE(Scope)
 
 SERVO_ARC_TYPE(AnimationValue, mozilla::StyleAnimationValue)
 SERVO_ARC_TYPE(ComputedStyle, mozilla::ComputedStyle)

layout/style/ServoBindings.h

@@ -87,6 +87,7 @@ BASIC_RULE_FUNCS_UNLOCKED(FontPaletteValues)
 BASIC_RULE_FUNCS_LOCKED(FontFace)
 BASIC_RULE_FUNCS_LOCKED(CounterStyle)
 GROUP_RULE_FUNCS_UNLOCKED(Container)
+GROUP_RULE_FUNCS_UNLOCKED(Scope)
 
 #undef GROUP_RULE_FUNCS_LOCKED
 #undef GROUP_RULE_FUNCS_UNLOCKED

layout/style/ServoCSSRuleList.cpp

@@ -24,6 +24,7 @@
 #include "mozilla/dom/CSSPropertyRule.h"
 #include "mozilla/dom/CSSStyleRule.h"
 #include "mozilla/dom/CSSSupportsRule.h"
+#include "mozilla/dom/CSSScopeRule.h"
 #include "mozilla/IntegerRange.h"
 #include "mozilla/ServoBindings.h"
 #include "mozilla/StyleSheet.h"
@@ -98,6 +99,7 @@ css::Rule* ServoCSSRuleList::GetRule(uint32_t aIndex) {
       CASE_RULE_UNLOCKED(LayerBlock, LayerBlock)
       CASE_RULE_UNLOCKED(LayerStatement, LayerStatement)
       CASE_RULE_UNLOCKED(Container, Container)
+      CASE_RULE_UNLOCKED(Scope, Scope)
 #undef CASE_RULE_LOCKED
 #undef CASE_RULE_UNLOCKED
 #undef CASE_RULE_WITH_PREFIX
@@ -276,6 +278,7 @@ void ServoCSSRuleList::SetRawContents(RefPtr<StyleLockedCssRules> aNewRules,
       RULE_CASE_UNLOCKED(LayerBlock, LayerBlock)
       RULE_CASE_UNLOCKED(LayerStatement, LayerStatement)
       RULE_CASE_UNLOCKED(Container, Container)
+      RULE_CASE_UNLOCKED(Scope, Scope)
       case StyleCssRuleType::Keyframe:
         MOZ_ASSERT_UNREACHABLE("keyframe rule cannot be here");
         break;

layout/style/ServoStyleConstsInlines.h

@@ -53,6 +53,7 @@ template struct StyleStrong<StyleFontPaletteValuesRule>;
 template struct StyleStrong<StyleLockedFontFaceRule>;
 template struct StyleStrong<StyleLockedCounterStyleRule>;
 template struct StyleStrong<StyleContainerRule>;
+template struct StyleStrong<StyleScopeRule>;
 
 template <typename T>
 inline void StyleOwnedSlice<T>::Clear() {

layout/style/ServoStyleSet.cpp

@@ -41,6 +41,7 @@
 #include "mozilla/dom/CSSNamespaceRule.h"
 #include "mozilla/dom/CSSPageRule.h"
 #include "mozilla/dom/CSSPropertyRule.h"
+#include "mozilla/dom/CSSScopeRule.h"
 #include "mozilla/dom/CSSSupportsRule.h"
 #include "mozilla/dom/FontFaceSet.h"
 #include "mozilla/dom/Element.h"
@@ -1002,6 +1003,7 @@ void ServoStyleSet::RuleChangedInternal(StyleSheet& aSheet, css::Rule& aRule,
     CASE_FOR(LayerBlock, LayerBlock)
     CASE_FOR(LayerStatement, LayerStatement)
     CASE_FOR(Container, Container)
+    CASE_FOR(Scope, Scope)
     // @namespace can only be inserted / removed when there are only other
     // @namespace and @import rules, and can't be mutated.
     case StyleCssRuleType::Namespace:

layout/style/moz.build

@@ -143,6 +143,7 @@ EXPORTS.mozilla.dom += [
     "CSSPageRule.h",
     "CSSPropertyRule.h",
     "CSSRuleList.h",
+    "CSSScopeRule.h",
     "CSSStyleRule.h",
     "CSSSupportsRule.h",
     "CSSValue.h",
@@ -194,6 +195,7 @@ UNIFIED_SOURCES += [
     "CSSPageRule.cpp",
     "CSSPropertyRule.cpp",
     "CSSRuleList.cpp",
+    "CSSScopeRule.cpp",
     "CSSStyleRule.cpp",
     "CSSSupportsRule.cpp",
     "DeclarationBlock.cpp",

modules/libpref/init/StaticPrefList.yaml

@@ -8752,6 +8752,13 @@
   mirror: always
   rust: true
 
+# Whether @scope rule is enabled
+- name: layout.css.at-scope.enabled
+  type: RelaxedAtomicBool
+  value: false
+  mirror: always
+  rust: true
+
 # Dictates whether or not the prefers contrast media query will be
 # usable.
 #   true: prefers-contrast will toggle based on OS and browser settings.

servo/components/selectors/parser.rs

@@ -469,6 +469,23 @@ impl<Impl: SelectorImpl> SelectorList<Impl> {
         )
     }
 
+    pub fn parse_forgiving<'i, 't, P>(
+        parser: &P,
+        input: &mut CssParser<'i, 't>,
+        parse_relative: ParseRelative,
+    ) -> Result<Self, ParseError<'i, P::Error>>
+    where
+        P: Parser<'i, Impl = Impl>,
+    {
+        Self::parse_with_state(
+            parser,
+            input,
+            SelectorParsingState::empty(),
+            ForgivingParsing::Yes,
+            parse_relative,
+        )
+    }
+
     #[inline]
     fn parse_with_state<'i, 't, P>(
         parser: &P,

servo/components/style/gecko/arc_types.rs

@@ -16,7 +16,7 @@ use crate::stylesheets::keyframes_rule::Keyframe;
 use crate::stylesheets::{
     ContainerRule, CounterStyleRule, CssRules, DocumentRule, FontFaceRule, FontFeatureValuesRule,
     FontPaletteValuesRule, ImportRule, KeyframesRule, LayerBlockRule, LayerStatementRule,
-    MediaRule, NamespaceRule, PageRule, PropertyRule, StyleRule, StylesheetContents, SupportsRule,
+    MediaRule, NamespaceRule, PageRule, PropertyRule, ScopeRule, StyleRule, StylesheetContents, SupportsRule,
 };
 use servo_arc::Arc;
 
@@ -169,3 +169,8 @@ impl_simple_arc_ffi!(
     Servo_AnimationValue_AddRef,
     Servo_AnimationValue_Release
 );
+impl_simple_arc_ffi!(
+    ScopeRule,
+    Servo_ScopeRule_AddRef,
+    Servo_ScopeRule_Release
+);

servo/components/style/invalidation/stylesheets.rs

@@ -646,6 +646,11 @@ impl StylesheetInvalidationSet {
                 debug!(" > Found unsupported rule, marking the whole subtree invalid.");
                 self.invalidate_fully();
             },
+            Scope(..) => {
+                // Addition/removal of @scope requires re-evaluation of scope proximity to properly
+                // figure out the styling order.
+                self.invalidate_fully();
+            },
         }
     }
 }