Make CSSRule always keep a pointer to its parent stylesheet

even when the parentStylesheet IDL attribute returns null.

components/script/dom/cssfontfacerule.rs

@@ -22,17 +22,18 @@ pub struct CSSFontFaceRule {
 }
 
 impl CSSFontFaceRule {
-    fn new_inherited(parent: Option<&CSSStyleSheet>, fontfacerule: Arc<RwLock<FontFaceRule>>) -> CSSFontFaceRule {
+    fn new_inherited(parent_stylesheet: &CSSStyleSheet, fontfacerule: Arc<RwLock<FontFaceRule>>)
+                     -> CSSFontFaceRule {
         CSSFontFaceRule {
-            cssrule: CSSRule::new_inherited(parent),
+            cssrule: CSSRule::new_inherited(parent_stylesheet),
             fontfacerule: fontfacerule,
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, parent: Option<&CSSStyleSheet>,
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet,
                fontfacerule: Arc<RwLock<FontFaceRule>>) -> Root<CSSFontFaceRule> {
-        reflect_dom_object(box CSSFontFaceRule::new_inherited(parent, fontfacerule),
+        reflect_dom_object(box CSSFontFaceRule::new_inherited(parent_stylesheet, fontfacerule),
                            window,
                            CSSFontFaceRuleBinding::Wrap)
     }

components/script/dom/cssgroupingrule.rs

@@ -4,7 +4,6 @@
 
 use dom::bindings::codegen::Bindings::CSSGroupingRuleBinding;
 use dom::bindings::codegen::Bindings::CSSGroupingRuleBinding::CSSGroupingRuleMethods;
-use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleBinding::CSSRuleMethods;
 use dom::bindings::error::{ErrorResult, Fallible};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::{JS, MutNullableHeap, Root};
@@ -25,27 +24,26 @@ pub struct CSSGroupingRule {
 }
 
 impl CSSGroupingRule {
-    pub fn new_inherited(parent: Option<&CSSStyleSheet>,
+    pub fn new_inherited(parent_stylesheet: &CSSStyleSheet,
                          rules: StyleCssRules) -> CSSGroupingRule {
         CSSGroupingRule {
-            cssrule: CSSRule::new_inherited(parent),
+            cssrule: CSSRule::new_inherited(parent_stylesheet),
             rules: rules,
             rulelist: MutNullableHeap::new(None),
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, parent: Option<&CSSStyleSheet>, rules: StyleCssRules) -> Root<CSSGroupingRule> {
-        reflect_dom_object(box CSSGroupingRule::new_inherited(parent, rules),
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet, rules: StyleCssRules) -> Root<CSSGroupingRule> {
+        reflect_dom_object(box CSSGroupingRule::new_inherited(parent_stylesheet, rules),
                            window,
                            CSSGroupingRuleBinding::Wrap)
     }
 
     fn rulelist(&self) -> Root<CSSRuleList> {
-        let sheet = self.upcast::<CSSRule>().GetParentStyleSheet();
-        let sheet = sheet.as_ref().map(|s| &**s);
+        let parent_stylesheet = self.upcast::<CSSRule>().parent_stylesheet();
         self.rulelist.or_init(|| CSSRuleList::new(self.global().as_window(),
-                                                  sheet,
+                                                  parent_stylesheet,
                                                   RulesSource::Rules(self.rules.clone())))
     }
 }

components/script/dom/csskeyframerule.rs

@@ -22,17 +22,18 @@ pub struct CSSKeyframeRule {
 }
 
 impl CSSKeyframeRule {
-    fn new_inherited(parent: Option<&CSSStyleSheet>, keyframerule: Arc<RwLock<Keyframe>>) -> CSSKeyframeRule {
+    fn new_inherited(parent_stylesheet: &CSSStyleSheet, keyframerule: Arc<RwLock<Keyframe>>)
+                     -> CSSKeyframeRule {
         CSSKeyframeRule {
-            cssrule: CSSRule::new_inherited(parent),
+            cssrule: CSSRule::new_inherited(parent_stylesheet),
             keyframerule: keyframerule,
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, parent: Option<&CSSStyleSheet>,
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet,
                keyframerule: Arc<RwLock<Keyframe>>) -> Root<CSSKeyframeRule> {
-        reflect_dom_object(box CSSKeyframeRule::new_inherited(parent, keyframerule),
+        reflect_dom_object(box CSSKeyframeRule::new_inherited(parent_stylesheet, keyframerule),
                            window,
                            CSSKeyframeRuleBinding::Wrap)
     }

components/script/dom/csskeyframesrule.rs

@@ -5,7 +5,6 @@
 use cssparser::Parser;
 use dom::bindings::codegen::Bindings::CSSKeyframesRuleBinding;
 use dom::bindings::codegen::Bindings::CSSKeyframesRuleBinding::CSSKeyframesRuleMethods;
-use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleMethods;
 use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::{JS, MutNullableHeap, Root};
@@ -32,28 +31,28 @@ pub struct CSSKeyframesRule {
 }
 
 impl CSSKeyframesRule {
-    fn new_inherited(parent: Option<&CSSStyleSheet>, keyframesrule: Arc<RwLock<KeyframesRule>>) -> CSSKeyframesRule {
+    fn new_inherited(parent_stylesheet: &CSSStyleSheet, keyframesrule: Arc<RwLock<KeyframesRule>>)
+                     -> CSSKeyframesRule {
         CSSKeyframesRule {
-            cssrule: CSSRule::new_inherited(parent),
+            cssrule: CSSRule::new_inherited(parent_stylesheet),
             keyframesrule: keyframesrule,
             rulelist: MutNullableHeap::new(None),
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, parent: Option<&CSSStyleSheet>,
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet,
                keyframesrule: Arc<RwLock<KeyframesRule>>) -> Root<CSSKeyframesRule> {
-        reflect_dom_object(box CSSKeyframesRule::new_inherited(parent, keyframesrule),
+        reflect_dom_object(box CSSKeyframesRule::new_inherited(parent_stylesheet, keyframesrule),
                            window,
                            CSSKeyframesRuleBinding::Wrap)
     }
 
     fn rulelist(&self) -> Root<CSSRuleList> {
         self.rulelist.or_init(|| {
-            let sheet = self.upcast::<CSSRule>().GetParentStyleSheet();
-            let sheet = sheet.as_ref().map(|s| &**s);
+            let parent_stylesheet = &self.upcast::<CSSRule>().parent_stylesheet();
             CSSRuleList::new(self.global().as_window(),
-                             sheet,
+                             parent_stylesheet,
                              RulesSource::Keyframes(self.keyframesrule.clone()))
         })
     }

components/script/dom/cssmediarule.rs

@@ -23,18 +23,19 @@ pub struct CSSMediaRule {
 }
 
 impl CSSMediaRule {
-    fn new_inherited(parent: Option<&CSSStyleSheet>, mediarule: Arc<RwLock<MediaRule>>) -> CSSMediaRule {
+    fn new_inherited(parent_stylesheet: &CSSStyleSheet, mediarule: Arc<RwLock<MediaRule>>)
+                     -> CSSMediaRule {
         let list = mediarule.read().rules.clone();
         CSSMediaRule {
-            cssrule: CSSGroupingRule::new_inherited(parent, list),
+            cssrule: CSSGroupingRule::new_inherited(parent_stylesheet, list),
             mediarule: mediarule,
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, parent: Option<&CSSStyleSheet>,
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet,
                mediarule: Arc<RwLock<MediaRule>>) -> Root<CSSMediaRule> {
-        reflect_dom_object(box CSSMediaRule::new_inherited(parent, mediarule),
+        reflect_dom_object(box CSSMediaRule::new_inherited(parent_stylesheet, mediarule),
                            window,
                            CSSMediaRuleBinding::Wrap)
     }

components/script/dom/cssnamespacerule.rs

@@ -23,17 +23,18 @@ pub struct CSSNamespaceRule {
 }
 
 impl CSSNamespaceRule {
-    fn new_inherited(parent: Option<&CSSStyleSheet>, namespacerule: Arc<RwLock<NamespaceRule>>) -> CSSNamespaceRule {
+    fn new_inherited(parent_stylesheet: &CSSStyleSheet, namespacerule: Arc<RwLock<NamespaceRule>>)
+                     -> CSSNamespaceRule {
         CSSNamespaceRule {
-            cssrule: CSSRule::new_inherited(parent),
+            cssrule: CSSRule::new_inherited(parent_stylesheet),
             namespacerule: namespacerule,
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, parent: Option<&CSSStyleSheet>,
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet,
                namespacerule: Arc<RwLock<NamespaceRule>>) -> Root<CSSNamespaceRule> {
-        reflect_dom_object(box CSSNamespaceRule::new_inherited(parent, namespacerule),
+        reflect_dom_object(box CSSNamespaceRule::new_inherited(parent_stylesheet, namespacerule),
                            window,
                            CSSNamespaceRuleBinding::Wrap)
     }

components/script/dom/cssrule.rs

@@ -5,7 +5,7 @@
 use dom::bindings::codegen::Bindings::CSSRuleBinding;
 use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleMethods;
 use dom::bindings::inheritance::Castable;
-use dom::bindings::js::{JS, MutNullableHeap, Root};
+use dom::bindings::js::{JS, Root};
 use dom::bindings::reflector::{Reflector, reflect_dom_object};
 use dom::bindings::str::DOMString;
 use dom::cssfontfacerule::CSSFontFaceRule;
@@ -17,27 +17,34 @@ use dom::cssstylerule::CSSStyleRule;
 use dom::cssstylesheet::CSSStyleSheet;
 use dom::cssviewportrule::CSSViewportRule;
 use dom::window::Window;
+use std::cell::Cell;
 use style::stylesheets::CssRule as StyleCssRule;
 
 
 #[dom_struct]
 pub struct CSSRule {
     reflector_: Reflector,
-    parent: MutNullableHeap<JS<CSSStyleSheet>>,
+    parent_stylesheet: JS<CSSStyleSheet>,
+
+    /// Whether the parentStyleSheet attribute should return null.
+    /// We keep parent_stylesheet in that case because insertRule needs it
+    /// for the stylesheet’s base URL and namespace prefixes.
+    parent_stylesheet_removed: Cell<bool>,
 }
 
 impl CSSRule {
     #[allow(unrooted_must_root)]
-    pub fn new_inherited(parent: Option<&CSSStyleSheet>) -> CSSRule {
+    pub fn new_inherited(parent_stylesheet: &CSSStyleSheet) -> CSSRule {
         CSSRule {
             reflector_: Reflector::new(),
-            parent: MutNullableHeap::new(parent),
+            parent_stylesheet: JS::from_ref(parent_stylesheet),
+            parent_stylesheet_removed: Cell::new(false),
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, parent: Option<&CSSStyleSheet>) -> Root<CSSRule> {
-        reflect_dom_object(box CSSRule::new_inherited(parent),
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet) -> Root<CSSRule> {
+        reflect_dom_object(box CSSRule::new_inherited(parent_stylesheet),
                            window,
                            CSSRuleBinding::Wrap)
     }
@@ -64,16 +71,16 @@ impl CSSRule {
 
     // Given a StyleCssRule, create a new instance of a derived class of
     // CSSRule based on which rule it is
-    pub fn new_specific(window: &Window, parent: Option<&CSSStyleSheet>,
+    pub fn new_specific(window: &Window, parent_stylesheet: &CSSStyleSheet,
                         rule: StyleCssRule) -> Root<CSSRule> {
         // be sure to update the match in as_specific when this is updated
         match rule {
-            StyleCssRule::Style(s) => Root::upcast(CSSStyleRule::new(window, parent, s)),
-            StyleCssRule::FontFace(s) => Root::upcast(CSSFontFaceRule::new(window, parent, s)),
-            StyleCssRule::Keyframes(s) => Root::upcast(CSSKeyframesRule::new(window, parent, s)),
-            StyleCssRule::Media(s) => Root::upcast(CSSMediaRule::new(window, parent, s)),
-            StyleCssRule::Namespace(s) => Root::upcast(CSSNamespaceRule::new(window, parent, s)),
-            StyleCssRule::Viewport(s) => Root::upcast(CSSViewportRule::new(window, parent, s)),
+            StyleCssRule::Style(s) => Root::upcast(CSSStyleRule::new(window, parent_stylesheet, s)),
+            StyleCssRule::FontFace(s) => Root::upcast(CSSFontFaceRule::new(window, parent_stylesheet, s)),
+            StyleCssRule::Keyframes(s) => Root::upcast(CSSKeyframesRule::new(window, parent_stylesheet, s)),
+            StyleCssRule::Media(s) => Root::upcast(CSSMediaRule::new(window, parent_stylesheet, s)),
+            StyleCssRule::Namespace(s) => Root::upcast(CSSNamespaceRule::new(window, parent_stylesheet, s)),
+            StyleCssRule::Viewport(s) => Root::upcast(CSSViewportRule::new(window, parent_stylesheet, s)),
         }
     }
 
@@ -85,12 +92,16 @@ impl CSSRule {
 
     /// Sets owner sheet to null (and does the same for all children)
     pub fn deparent(&self) {
-        self.parent.set(None);
+        self.parent_stylesheet_removed.set(true);
         // https://github.com/w3c/csswg-drafts/issues/722
         // Spec doesn't ask us to do this, but it makes sense
         // and browsers implement this behavior
         self.as_specific().deparent_children();
     }
+
+    pub fn parent_stylesheet(&self) -> &CSSStyleSheet {
+        &self.parent_stylesheet
+    }
 }
 
 impl CSSRuleMethods for CSSRule {
@@ -101,7 +112,11 @@ impl CSSRuleMethods for CSSRule {
 
     // https://drafts.csswg.org/cssom/#dom-cssrule-parentstylesheet
     fn GetParentStyleSheet(&self) -> Option<Root<CSSStyleSheet>> {
-        self.parent.get()
+        if self.parent_stylesheet_removed.get() {
+            None
+        } else {
+            Some(Root::from_ref(&*self.parent_stylesheet))
+        }
     }
 
     // https://drafts.csswg.org/cssom/#dom-cssrule-csstext
@@ -118,7 +133,7 @@ impl CSSRuleMethods for CSSRule {
 pub trait SpecificCSSRule {
     fn ty(&self) -> u16;
     fn get_css(&self) -> DOMString;
-    /// Remove CSSStyleSheet parent from all transitive children
+    /// Remove parentStylesheet from all transitive children
     fn deparent_children(&self) {
         // most CSSRules do nothing here
     }

components/script/dom/cssrulelist.rs

@@ -34,7 +34,7 @@ impl From<RulesMutateError> for Error {
 #[dom_struct]
 pub struct CSSRuleList {
     reflector_: Reflector,
-    sheet: MutNullableHeap<JS<CSSStyleSheet>>,
+    parent_stylesheet: JS<CSSStyleSheet>,
     #[ignore_heap_size_of = "Arc"]
     rules: RulesSource,
     dom_rules: DOMRefCell<Vec<MutNullableHeap<JS<CSSRule>>>>
@@ -47,7 +47,7 @@ pub enum RulesSource {
 
 impl CSSRuleList {
     #[allow(unrooted_must_root)]
-    pub fn new_inherited(sheet: Option<&CSSStyleSheet>, rules: RulesSource) -> CSSRuleList {
+    pub fn new_inherited(parent_stylesheet: &CSSStyleSheet, rules: RulesSource) -> CSSRuleList {
         let dom_rules = match rules {
             RulesSource::Rules(ref rules) => {
                 rules.0.read().iter().map(|_| MutNullableHeap::new(None)).collect()
@@ -59,16 +59,16 @@ impl CSSRuleList {
 
         CSSRuleList {
             reflector_: Reflector::new(),
-            sheet: MutNullableHeap::new(sheet),
+            parent_stylesheet: JS::from_ref(parent_stylesheet),
             rules: rules,
             dom_rules: DOMRefCell::new(dom_rules),
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, sheet: Option<&CSSStyleSheet>,
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet,
                rules: RulesSource) -> Root<CSSRuleList> {
-        reflect_dom_object(box CSSRuleList::new_inherited(sheet, rules),
+        reflect_dom_object(box CSSRuleList::new_inherited(parent_stylesheet, rules),
                            window,
                            CSSRuleListBinding::Wrap)
     }
@@ -89,9 +89,8 @@ impl CSSRuleList {
 
         let new_rule = css_rules.insert_rule(rule, doc.url().clone(), index, nested)?;
 
-        let sheet = self.sheet.get();
-        let sheet = sheet.as_ref().map(|sheet| &**sheet);
-        let dom_rule = CSSRule::new_specific(&window, sheet, new_rule);
+        let parent_stylesheet = &*self.parent_stylesheet;
+        let dom_rule = CSSRule::new_specific(&window, parent_stylesheet, new_rule);
         self.dom_rules.borrow_mut().insert(index, MutNullableHeap::new(Some(&*dom_rule)));
         Ok((idx))
     }
@@ -129,17 +128,16 @@ impl CSSRuleList {
     pub fn item(&self, idx: u32) -> Option<Root<CSSRule>> {
         self.dom_rules.borrow().get(idx as usize).map(|rule| {
             rule.or_init(|| {
-                let sheet = self.sheet.get();
-                let sheet = sheet.as_ref().map(|sheet| &**sheet);
+                let parent_stylesheet = &self.parent_stylesheet;
                 match self.rules {
                     RulesSource::Rules(ref rules) => {
                         CSSRule::new_specific(self.global().as_window(),
-                                             sheet,
+                                             parent_stylesheet,
                                              rules.0.read()[idx as usize].clone())
                     }
                     RulesSource::Keyframes(ref rules) => {
                         Root::upcast(CSSKeyframeRule::new(self.global().as_window(),
-                                                          sheet,
+                                                          parent_stylesheet,
                                                           rules.read()
                                                                 .keyframes[idx as usize]
                                                                 .clone()))

components/script/dom/cssstylerule.rs

@@ -22,17 +22,18 @@ pub struct CSSStyleRule {
 }
 
 impl CSSStyleRule {
-    fn new_inherited(parent: Option<&CSSStyleSheet>, stylerule: Arc<RwLock<StyleRule>>) -> CSSStyleRule {
+    fn new_inherited(parent_stylesheet: &CSSStyleSheet, stylerule: Arc<RwLock<StyleRule>>)
+                     -> CSSStyleRule {
         CSSStyleRule {
-            cssrule: CSSRule::new_inherited(parent),
+            cssrule: CSSRule::new_inherited(parent_stylesheet),
             stylerule: stylerule,
         }
     }
 
     #[allow(unrooted_must_root)]
-    pub fn new(window: &Window, parent: Option<&CSSStyleSheet>,
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet,
                stylerule: Arc<RwLock<StyleRule>>) -> Root<CSSStyleRule> {
-        reflect_dom_object(box CSSStyleRule::new_inherited(parent, stylerule),
+        reflect_dom_object(box CSSStyleRule::new_inherited(parent_stylesheet, stylerule),
                            window,
                            CSSStyleRuleBinding::Wrap)
     }

components/script/dom/cssstylesheet.rs

@@ -53,7 +53,7 @@ impl CSSStyleSheet {
 
     fn rulelist(&self) -> Root<CSSRuleList> {
         self.rulelist.or_init(|| CSSRuleList::new(self.global().as_window(),
-                                                  Some(self),
+                                                  self,
                                                   RulesSource::Rules(self.style_stylesheet
                                                                          .rules.clone())))
     }