Bug 1889496 - Part 2: Implement CSSStartingStyleRule interface. r=webidl,firefox-style-system-reviewers,layout-reviewers,emilio

Introduce CSSStartingStyleRule and add one extra parsing test for
@starting-style rule.

Differential Revision: https://phabricator.services.mozilla.com/D206564

dom/tests/mochitest/general/mochitest.toml

@@ -1,5 +1,8 @@
 [DEFAULT]
-prefs = ["dom.svg.pathSeg.enabled=false"]
+prefs = [
+  "dom.svg.pathSeg.enabled=false",
+  "layout.css.starting-style-at-rules.enabled=true",
+]
 support-files = [
   "497633.html",
   "fail.png",

dom/tests/mochitest/general/test_interfaces.js

@@ -328,6 +328,8 @@ let interfaceNamesInGlobalScope = [
   // IMPORTANT: Do not change this list without review from a DOM peer!
   { name: "CSSRuleList", insecureContext: true },
   // IMPORTANT: Do not change this list without review from a DOM peer!
+  { name: "CSSStartingStyleRule", insecureContext: true, nightly: true },
+  // IMPORTANT: Do not change this list without review from a DOM peer!
   { name: "CSSStyleDeclaration", insecureContext: true },
   // IMPORTANT: Do not change this list without review from a DOM peer!
   { name: "CSSStyleRule", insecureContext: true },

dom/webidl/CSSStartingStyleRule.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/.
+ *
+ * The origin of this IDL file is
+ * https://drafts.csswg.org/css-transitions-2/#the-cssstartingstylerule-interface
+ */
+
+[Exposed=Window, Pref="layout.css.starting-style-at-rules.enabled"]
+interface CSSStartingStyleRule : CSSGroupingRule {
+};

dom/webidl/moz.build

@@ -497,6 +497,7 @@ WEBIDL_FILES = [
     "CSSRule.webidl",
     "CSSRuleList.webidl",
     "CSSScopeRule.webidl",
+    "CSSStartingStyleRule.webidl",
     "CSSStyleDeclaration.webidl",
     "CSSStyleRule.webidl",
     "CSSStyleSheet.webidl",

layout/inspector/InspectorUtils.cpp

@@ -434,6 +434,7 @@ static uint32_t CollectAtRules(ServoCSSRuleList& aRuleList,
       case StyleCssRuleType::FontFeatureValues:
       case StyleCssRuleType::FontPaletteValues:
       case StyleCssRuleType::Scope:
+      case StyleCssRuleType::StartingStyle:
         break;
     }
 

layout/inspector/ServoStyleRuleMap.cpp

@@ -87,7 +87,8 @@ void ServoStyleRuleMap::RuleRemoved(StyleSheet& aStyleSheet,
     case StyleCssRuleType::LayerBlock:
     case StyleCssRuleType::Container:
     case StyleCssRuleType::Document:
-    case StyleCssRuleType::Scope: {
+    case StyleCssRuleType::Scope:
+    case StyleCssRuleType::StartingStyle: {
       // See the comment in SheetRemoved.
       mTable.Clear();
       break;
@@ -126,7 +127,8 @@ void ServoStyleRuleMap::FillTableFromRule(css::Rule& aRule) {
     case StyleCssRuleType::Supports:
     case StyleCssRuleType::Container:
     case StyleCssRuleType::Document:
-    case StyleCssRuleType::Scope: {
+    case StyleCssRuleType::Scope:
+    case StyleCssRuleType::StartingStyle: {
       auto& rule = static_cast<css::GroupRule&>(aRule);
       FillTableFromRuleList(*rule.CssRules());
       break;

layout/style/CSSStartingStyleRule.cpp

@@ -0,0 +1,47 @@
+/* -*- 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/CSSStartingStyleRule.h"
+#include "mozilla/dom/CSSStartingStyleRuleBinding.h"
+#include "mozilla/ServoBindings.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED_0(CSSStartingStyleRule,
+                                               css::GroupRule)
+
+// QueryInterface implementation for SupportsRule
+
+#ifdef DEBUG
+void CSSStartingStyleRule::List(FILE* out, int32_t aIndent) const {
+  nsAutoCString str;
+  for (int32_t i = 0; i < aIndent; i++) {
+    str.AppendLiteral("  ");
+  }
+  Servo_StartingStyleRule_Debug(mRawRule, &str);
+  fprintf_stderr(out, "%s\n", str.get());
+}
+#endif
+
+StyleCssRuleType CSSStartingStyleRule::Type() const {
+  return StyleCssRuleType::StartingStyle;
+}
+
+already_AddRefed<StyleLockedCssRules>
+CSSStartingStyleRule::GetOrCreateRawRules() {
+  return Servo_StartingStyleRule_GetRules(mRawRule).Consume();
+}
+
+void CSSStartingStyleRule::GetCssText(nsACString& aCssText) const {
+  Servo_StartingStyleRule_GetCssText(mRawRule.get(), &aCssText);
+}
+
+JSObject* CSSStartingStyleRule::WrapObject(JSContext* aCx,
+                                           JS::Handle<JSObject*> aGivenProto) {
+  return CSSStartingStyleRule_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+}  // namespace mozilla::dom

layout/style/CSSStartingStyleRule.h

@@ -0,0 +1,54 @@
+/* -*- 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 CSSStaringStyleRule_h___
+#define CSSStaringStyleRule_h___
+
+#include "mozilla/css/GroupRule.h"
+#include "mozilla/ServoBindingTypes.h"
+
+namespace mozilla::dom {
+
+class CSSStartingStyleRule final : public css::GroupRule {
+ public:
+  CSSStartingStyleRule(RefPtr<StyleStartingStyleRule> aRawRule,
+                       StyleSheet* aSheet, css::Rule* aParentRule,
+                       uint32_t aLine, uint32_t aColumn)
+      : css::GroupRule(aSheet, aParentRule, aLine, aColumn),
+        mRawRule(std::move(aRawRule)) {}
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+#ifdef DEBUG
+  void List(FILE* out = stdout, int32_t aIndent = 0) const final;
+#endif
+
+  StyleStartingStyleRule* Raw() const { return mRawRule; }
+  void SetRawAfterClone(RefPtr<StyleStartingStyleRule> aRaw) {
+    mRawRule = std::move(aRaw);
+    css::GroupRule::DidSetRawAfterClone();
+  }
+
+  already_AddRefed<StyleLockedCssRules> GetOrCreateRawRules() final;
+
+  // WebIDL interface
+  StyleCssRuleType Type() const final;
+  void GetCssText(nsACString& aCssText) const final;
+
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+  JSObject* WrapObject(JSContext*, JS::Handle<JSObject*>) override;
+
+ private:
+  ~CSSStartingStyleRule() = default;
+
+  RefPtr<StyleStartingStyleRule> mRawRule;
+};
+
+}  // namespace mozilla::dom
+
+#endif

layout/style/Rule.cpp

@@ -100,13 +100,15 @@ 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 || type == StyleCssRuleType::Scope);
+    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 ||
+               type == StyleCssRuleType::StartingStyle);
   }
 }
 #endif

layout/style/ServoBindingTypes.h

@@ -130,6 +130,7 @@ UNLOCKED_RULE_TYPE(Document)
 UNLOCKED_RULE_TYPE(FontFeatureValues)
 UNLOCKED_RULE_TYPE(FontPaletteValues)
 UNLOCKED_RULE_TYPE(Scope)
+UNLOCKED_RULE_TYPE(StartingStyle)
 
 SERVO_ARC_TYPE(AnimationValue, mozilla::StyleAnimationValue)
 SERVO_ARC_TYPE(ComputedStyle, mozilla::ComputedStyle)

layout/style/ServoBindings.h

@@ -88,6 +88,7 @@ BASIC_RULE_FUNCS_LOCKED(FontFace)
 BASIC_RULE_FUNCS_LOCKED(CounterStyle)
 GROUP_RULE_FUNCS_UNLOCKED(Container)
 GROUP_RULE_FUNCS_UNLOCKED(Scope)
+GROUP_RULE_FUNCS_UNLOCKED(StartingStyle)
 
 #undef GROUP_RULE_FUNCS_LOCKED
 #undef GROUP_RULE_FUNCS_UNLOCKED

layout/style/ServoCSSRuleList.cpp

@@ -22,9 +22,10 @@
 #include "mozilla/dom/CSSNamespaceRule.h"
 #include "mozilla/dom/CSSPageRule.h"
 #include "mozilla/dom/CSSPropertyRule.h"
+#include "mozilla/dom/CSSScopeRule.h"
+#include "mozilla/dom/CSSStartingStyleRule.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"
@@ -100,15 +101,13 @@ css::Rule* ServoCSSRuleList::GetRule(uint32_t aIndex) {
       CASE_RULE_UNLOCKED(LayerStatement, LayerStatement)
       CASE_RULE_UNLOCKED(Container, Container)
       CASE_RULE_UNLOCKED(Scope, Scope)
+      CASE_RULE_UNLOCKED(StartingStyle, StartingStyle)
 #undef CASE_RULE_LOCKED
 #undef CASE_RULE_UNLOCKED
 #undef CASE_RULE_WITH_PREFIX
       case StyleCssRuleType::Keyframe:
         MOZ_ASSERT_UNREACHABLE("keyframe rule cannot be here");
         return nullptr;
-      case StyleCssRuleType::StartingStyle:
-        // TODO: Implement this in the following patch.
-        return nullptr;
       case StyleCssRuleType::Margin:
         // Margin rules not implemented yet, see bug 1864737
         return nullptr;
@@ -291,9 +290,7 @@ void ServoCSSRuleList::SetRawContents(RefPtr<StyleLockedCssRules> aNewRules,
       RULE_CASE_UNLOCKED(LayerStatement, LayerStatement)
       RULE_CASE_UNLOCKED(Container, Container)
       RULE_CASE_UNLOCKED(Scope, Scope)
-      case StyleCssRuleType::StartingStyle:
-        // TODO: Implement this in the following patch.
-        break;
+      RULE_CASE_UNLOCKED(StartingStyle, StartingStyle)
       case StyleCssRuleType::Keyframe:
         MOZ_ASSERT_UNREACHABLE("keyframe rule cannot be here");
         break;

layout/style/ServoStyleConstsInlines.h

@@ -54,6 +54,7 @@ template struct StyleStrong<StyleLockedFontFaceRule>;
 template struct StyleStrong<StyleLockedCounterStyleRule>;
 template struct StyleStrong<StyleContainerRule>;
 template struct StyleStrong<StyleScopeRule>;
+template struct StyleStrong<StyleStartingStyleRule>;
 
 template <typename T>
 inline void StyleOwnedSlice<T>::Clear() {

layout/style/ServoStyleSet.cpp

@@ -43,6 +43,7 @@
 #include "mozilla/dom/CSSPropertyRule.h"
 #include "mozilla/dom/CSSScopeRule.h"
 #include "mozilla/dom/CSSSupportsRule.h"
+#include "mozilla/dom/CSSStartingStyleRule.h"
 #include "mozilla/dom/FontFaceSet.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/ElementInlines.h"
@@ -1004,9 +1005,7 @@ void ServoStyleSet::RuleChangedInternal(StyleSheet& aSheet, css::Rule& aRule,
     CASE_FOR(LayerStatement, LayerStatement)
     CASE_FOR(Container, Container)
     CASE_FOR(Scope, Scope)
-    case StyleCssRuleType::StartingStyle:
-      // TODO: Implement this in the following patch.
-      break;
+    CASE_FOR(StartingStyle, StartingStyle)
     // @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

@@ -145,6 +145,7 @@ EXPORTS.mozilla.dom += [
     "CSSPropertyRule.h",
     "CSSRuleList.h",
     "CSSScopeRule.h",
+    "CSSStartingStyleRule.h",
     "CSSStyleRule.h",
     "CSSSupportsRule.h",
     "CSSValue.h",
@@ -197,6 +198,7 @@ UNIFIED_SOURCES += [
     "CSSPropertyRule.cpp",
     "CSSRuleList.cpp",
     "CSSScopeRule.cpp",
+    "CSSStartingStyleRule.cpp",
     "CSSStyleRule.cpp",
     "CSSSupportsRule.cpp",
     "DeclarationBlock.cpp",

servo/components/style/gecko/arc_types.rs

@@ -16,7 +16,8 @@ use crate::stylesheets::keyframes_rule::Keyframe;
 use crate::stylesheets::{
     ContainerRule, CounterStyleRule, CssRules, DocumentRule, FontFaceRule, FontFeatureValuesRule,
     FontPaletteValuesRule, ImportRule, KeyframesRule, LayerBlockRule, LayerStatementRule,
-    MediaRule, NamespaceRule, PageRule, PropertyRule, ScopeRule, StyleRule, StylesheetContents, SupportsRule,
+    MediaRule, NamespaceRule, PageRule, PropertyRule, ScopeRule, StartingStyleRule, StyleRule,
+    StylesheetContents, SupportsRule,
 };
 use servo_arc::Arc;
 
@@ -174,3 +175,8 @@ impl_simple_arc_ffi!(
     Servo_ScopeRule_AddRef,
     Servo_ScopeRule_Release
 );
+impl_simple_arc_ffi!(
+    StartingStyleRule,
+    Servo_StartingStyleRule_AddRef,
+    Servo_StartingStyleRule_Release
+);

servo/ports/geckolib/glue.rs

@@ -138,7 +138,7 @@ use style::stylesheets::{
     CssRules, CssRulesHelpers, DocumentRule, FontFaceRule, FontFeatureValuesRule,
     FontPaletteValuesRule, ImportRule, KeyframesRule, LayerBlockRule, LayerStatementRule,
     MediaRule, NamespaceRule, Origin, OriginSet, PagePseudoClassFlags, PageRule, PropertyRule,
-    SanitizationData, SanitizationKind, StyleRule, StylesheetContents,
+    SanitizationData, SanitizationKind, StartingStyleRule, StyleRule, StylesheetContents,
     StylesheetLoader as StyleStylesheetLoader, SupportsRule, UrlExtraData, ScopeRule,
 };
 use style::stylist::{add_size_of_ua_cache, AuthorStylesEnabled, RuleInclusion, Stylist};
@@ -2499,6 +2499,14 @@ impl_group_rule_funcs! { (Scope, ScopeRule, ScopeRule),
     changed: Servo_StyleSet_ScopeRuleChanged,
 }
 
+impl_group_rule_funcs! { (StartingStyle, StartingStyleRule, StartingStyleRule),
+    get_rules: Servo_StartingStyleRule_GetRules,
+    getter: Servo_CssRules_GetStartingStyleRuleAt,
+    debug: Servo_StartingStyleRule_Debug,
+    to_css: Servo_StartingStyleRule_GetCssText,
+    changed: Servo_StyleSet_StartingStyleRuleChanged,
+}
+
 #[no_mangle]
 pub extern "C" fn Servo_StyleRule_GetStyle(
     rule: &LockedStyleRule,

testing/web-platform/meta/css/css-transitions/idlharness-2.html.ini

@@ -1,24 +0,0 @@
-[idlharness-2.html]
-  [CSSStartingStyleRule interface: existence and properties of interface object]
-    expected: FAIL
-
-  [CSSStartingStyleRule interface object length]
-    expected: FAIL
-
-  [CSSStartingStyleRule interface object name]
-    expected: FAIL
-
-  [CSSStartingStyleRule interface: existence and properties of interface prototype object]
-    expected: FAIL
-
-  [CSSStartingStyleRule interface: existence and properties of interface prototype object's "constructor" property]
-    expected: FAIL
-
-  [CSSStartingStyleRule interface: existence and properties of interface prototype object's @@unscopables property]
-    expected: FAIL
-
-  [CSSStartingStyleRule must be primary interface of sheet.cssRules[0\]]
-    expected: FAIL
-
-  [Stringification of sheet.cssRules[0\]]
-    expected: FAIL

testing/web-platform/tests/css/css-transitions/parsing/starting-style-parsing.html

@@ -0,0 +1,38 @@
+<!doctype html>
+<title>@starting-style: parsing</title>
+<link rel="help" href="https://drafts.csswg.org/css-transitions-2/#at-ruledef-starting-style">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<main id=main></main>
+<script>
+  function test_valid(actual, expected) {
+    if (expected === undefined)
+      expected = actual;
+    test(t => {
+      t.add_cleanup(() => main.replaceChildren());
+      let style = document.createElement('style');
+      style.textContent = `${actual}{}`;
+      main.append(style);
+      assert_equals(style.sheet.rules.length, 1);
+      let rule = style.sheet.rules[0];
+      assert_equals(rule.cssText, `${expected} {\n}`);
+    }, `${actual} is valid`);
+  }
+
+  function test_invalid(actual) {
+    test(t => {
+      t.add_cleanup(() => main.replaceChildren());
+      let style = document.createElement('style');
+      style.textContent = `${actual}{}`;
+      main.append(style);
+      assert_equals(style.sheet.rules.length, 0);
+    }, `${actual} is not valid`);
+  }
+
+  test_valid('@starting-style');
+
+  test_invalid('@starting-style div');
+  test_invalid('@starting-style ()');
+  test_invalid('@starting-style ( {}');
+  test_invalid('@starting-style }');
+</script>