Merge normal and important declarations in style rules.

Have a single Vec instead of two. Fix #3426

components/script/dom/cssstyledeclaration.rs

@@ -92,7 +92,7 @@ impl CSSStyleDeclarationMethods for CSSStyleDeclaration {
     fn Length(&self) -> u32 {
         let elem = self.owner.upcast::<Element>();
         let len = match *elem.style_attribute().borrow() {
-            Some(ref declarations) => declarations.normal.len() + declarations.important.len(),
+            Some(ref declarations) => declarations.declarations.len(),
             None => 0,
         };
         len as u32
@@ -103,19 +103,15 @@ impl CSSStyleDeclarationMethods for CSSStyleDeclaration {
         let index = index as usize;
         let elem = self.owner.upcast::<Element>();
         let style_attribute = elem.style_attribute().borrow();
-        let result = style_attribute.as_ref().and_then(|declarations| {
-            if index > declarations.normal.len() {
-                declarations.important
-                            .get(index - declarations.normal.len())
-                            .map(|decl| format!("{:?} !important", decl))
-            } else {
-                declarations.normal
-                            .get(index)
-                            .map(|decl| format!("{:?}", decl))
+        style_attribute.as_ref().and_then(|declarations| {
+            declarations.declarations.get(index)
+        }).map(|&(ref declaration, importance)| {
+            let mut css = declaration.to_css_string();
+            if importance.important() {
+                css += " !important";
             }
-        });
-
-        result.map_or(DOMString::new(), DOMString::from)
+            DOMString::from(css)
+        }).unwrap_or_else(DOMString::new)
     }
 
     // https://dev.w3.org/csswg/cssom/#dom-cssstyledeclaration-getpropertyvalue
@@ -151,11 +147,11 @@ impl CSSStyleDeclarationMethods for CSSStyleDeclaration {
             // Step 2.3
             // Work around closures not being Clone
             #[derive(Clone)]
-            struct Map<'a, 'b: 'a>(slice::Iter<'a, Ref<'b, PropertyDeclaration>>);
+            struct Map<'a, 'b: 'a>(slice::Iter<'a, Ref<'b, (PropertyDeclaration, Importance)>>);
             impl<'a, 'b> Iterator for Map<'a, 'b> {
                 type Item = &'a PropertyDeclaration;
                 fn next(&mut self) -> Option<Self::Item> {
-                    self.0.next().map(|r| &**r)
+                    self.0.next().map(|r| &r.0)
                 }
             }
 
@@ -167,7 +163,7 @@ impl CSSStyleDeclarationMethods for CSSStyleDeclaration {
 
         // Step 3 & 4
         match owner.get_inline_style_declaration(&property) {
-            Some(declaration) => DOMString::from(declaration.value()),
+            Some(declaration) => DOMString::from(declaration.0.value()),
             None => DOMString::new(),
         }
     }
@@ -188,8 +184,10 @@ impl CSSStyleDeclarationMethods for CSSStyleDeclaration {
             }
         // Step 3
         } else {
-            if self.owner.get_important_inline_style_declaration(&property).is_some() {
-                return DOMString::from("important");
+            if let Some(decl) = self.owner.get_inline_style_declaration(&property) {
+                if decl.1.important() {
+                    return DOMString::from("important");
+                }
             }
         }
 
@@ -366,7 +364,7 @@ impl CSSStyleDeclarationMethods for CSSStyleDeclaration {
         // Step 3
         let decl_block = parse_style_attribute(&value, &window.get_url(), window.css_error_reporter(),
                                                ParserContextExtraData::default());
-        *element.style_attribute().borrow_mut() = if decl_block.normal.is_empty() && decl_block.important.is_empty() {
+        *element.style_attribute().borrow_mut() = if decl_block.declarations.is_empty() {
             None // Step 2
         } else {
             Some(decl_block)

components/script/dom/element.rs

@@ -80,7 +80,6 @@ use std::cell::{Cell, Ref};
 use std::convert::TryFrom;
 use std::default::Default;
 use std::fmt;
-use std::mem;
 use std::sync::Arc;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use string_cache::{Atom, Namespace, QualName};
@@ -329,7 +328,9 @@ impl LayoutElementHelpers for LayoutJS<Element> {
     {
         #[inline]
         fn from_declaration(rule: PropertyDeclaration) -> DeclarationBlock {
-            DeclarationBlock::from_declarations(Arc::new(vec![rule]))
+            DeclarationBlock::from_declarations(
+                Arc::new(vec![(rule, Importance::Normal)]),
+                Importance::Normal)
         }
 
         let bgcolor = if let Some(this) = self.downcast::<HTMLBodyElement>() {
@@ -761,20 +762,11 @@ impl Element {
         fn remove(element: &Element, property: &str) {
             let mut inline_declarations = element.style_attribute.borrow_mut();
             if let &mut Some(ref mut declarations) = &mut *inline_declarations {
-                let index = declarations.normal
+                let index = declarations.declarations
                                         .iter()
-                                        .position(|decl| decl.matches(property));
+                                        .position(|&(ref decl, _)| decl.matches(property));
                 if let Some(index) = index {
-                    Arc::make_mut(&mut declarations.normal).remove(index);
-                    return;
-                }
-
-                let index = declarations.important
-                                        .iter()
-                                        .position(|decl| decl.matches(property));
-                if let Some(index) = index {
-                    Arc::make_mut(&mut declarations.important).remove(index);
-                    return;
+                    Arc::make_mut(&mut declarations.declarations).remove(index);
                 }
             }
         }
@@ -786,47 +778,29 @@ impl Element {
     pub fn update_inline_style(&self,
                                declarations: Vec<PropertyDeclaration>,
                                importance: Importance) {
-        fn update(element: &Element, mut declarations: Vec<PropertyDeclaration>,
+        fn update(element: &Element, declarations: Vec<PropertyDeclaration>,
                   importance: Importance) {
             let mut inline_declarations = element.style_attribute().borrow_mut();
             if let &mut Some(ref mut existing_declarations) = &mut *inline_declarations {
-                let existing_declarations = if importance.important() {
-                    &mut existing_declarations.important
-                } else {
-                    &mut existing_declarations.normal
-                };
-
                 // Usually, the reference count will be 1 here. But transitions could make it greater
                 // than that.
-                let existing_declarations = Arc::make_mut(existing_declarations);
+                let existing_declarations = Arc::make_mut(&mut existing_declarations.declarations);
 
-                for mut incoming_declaration in declarations {
-                    let mut replaced = false;
+                'outer: for incoming_declaration in declarations {
                     for existing_declaration in &mut *existing_declarations {
-                        if existing_declaration.name() == incoming_declaration.name() {
-                            mem::swap(existing_declaration, &mut incoming_declaration);
-                            replaced = true;
-                            break;
+                        if existing_declaration.0.name() == incoming_declaration.name() {
+                            *existing_declaration = (incoming_declaration, importance);
+                            continue 'outer;
                         }
                     }
-
-                    if !replaced {
-                        existing_declarations.push(incoming_declaration);
-                    }
+                    existing_declarations.push((incoming_declaration, importance));
                 }
 
                 return;
             }
 
-            let (important, normal) = if importance.important() {
-                (declarations, vec![])
-            } else {
-                (vec![], declarations)
-            };
-
             *inline_declarations = Some(PropertyDeclarationBlock {
-                important: Arc::new(important),
-                normal: Arc::new(normal),
+                declarations: Arc::new(declarations.into_iter().map(|d| (d, importance)).collect()),
             });
         }
 
@@ -836,30 +810,18 @@ impl Element {
 
     pub fn set_inline_style_property_priority(&self,
                                               properties: &[&str],
-                                              importance: Importance) {
+                                              new_importance: Importance) {
         {
             let mut inline_declarations = self.style_attribute().borrow_mut();
             if let &mut Some(ref mut declarations) = &mut *inline_declarations {
-              let (from, to) = if importance == Importance::Important {
-                  (&mut declarations.normal, &mut declarations.important)
-              } else {
-                  (&mut declarations.important, &mut declarations.normal)
-              };
-
-              // Usually, the reference counts of `from` and `to` will be 1 here. But transitions
-              // could make them greater than that.
-              let from = Arc::make_mut(from);
-              let to = Arc::make_mut(to);
-              let mut new_from = Vec::new();
-              for declaration in from.drain(..) {
-                  let name = declaration.name();
-                  if properties.iter().any(|p| name == **p) {
-                      to.push(declaration)
-                  } else {
-                      new_from.push(declaration)
-                  }
-              }
-              mem::replace(from, new_from);
+                // Usually, the reference counts of `from` and `to` will be 1 here. But transitions
+                // could make them greater than that.
+                let declarations = Arc::make_mut(&mut declarations.declarations);
+                for &mut (ref declaration, ref mut importance) in declarations {
+                    if properties.iter().any(|p| declaration.name() == **p) {
+                        *importance = new_importance
+                    }
+                }
             }
         }
 
@@ -868,25 +830,12 @@ impl Element {
 
     pub fn get_inline_style_declaration(&self,
                                         property: &Atom)
-                                        -> Option<Ref<PropertyDeclaration>> {
-        ref_filter_map(self.style_attribute.borrow(), |inline_declarations| {
-            inline_declarations.as_ref().and_then(|declarations| {
-                declarations.normal
-                            .iter()
-                            .chain(declarations.important.iter())
-                            .find(|decl| decl.matches(&property))
-            })
-        })
-    }
-
-    pub fn get_important_inline_style_declaration(&self,
-                                                  property: &Atom)
-                                                  -> Option<Ref<PropertyDeclaration>> {
+                                        -> Option<Ref<(PropertyDeclaration, Importance)>> {
         ref_filter_map(self.style_attribute.borrow(), |inline_declarations| {
             inline_declarations.as_ref().and_then(|declarations| {
-                declarations.important
+                declarations.declarations
                             .iter()
-                            .find(|decl| decl.matches(&property))
+                            .find(|&&(ref decl, _)| decl.matches(&property))
             })
         })
     }

components/style/animation.rs

@@ -15,7 +15,7 @@ use properties::longhands::animation_iteration_count::computed_value::AnimationI
 use properties::longhands::animation_play_state::computed_value::AnimationPlayState;
 use properties::longhands::transition_timing_function::computed_value::StartEnd;
 use properties::longhands::transition_timing_function::computed_value::TransitionTimingFunction;
-use properties::{self, ComputedValues};
+use properties::{self, ComputedValues, Importance};
 use selector_matching::DeclarationBlock;
 use std::sync::Arc;
 use std::sync::mpsc::Sender;
@@ -385,7 +385,8 @@ fn compute_style_for_animation_step(context: &SharedStyleContext,
         KeyframesStepValue::ComputedValues => style_from_cascade.clone(),
         KeyframesStepValue::Declarations(ref declarations) => {
             let declaration_block = DeclarationBlock {
-                declarations: declarations.clone(),
+                mixed_declarations: declarations.clone(),
+                importance: Importance::Normal,
                 source_order: 0,
                 specificity: ::std::u32::MAX,
             };

components/style/keyframes.rs

@@ -5,9 +5,9 @@
 use cssparser::{AtRuleParser, Parser, QualifiedRuleParser, RuleListParser};
 use cssparser::{DeclarationListParser, DeclarationParser};
 use parser::{ParserContext, log_css_error};
-use properties::PropertyDeclaration;
 use properties::PropertyDeclarationParseResult;
 use properties::animated_properties::TransitionProperty;
+use properties::{PropertyDeclaration, Importance};
 use std::sync::Arc;
 
 /// A number from 1 to 100, indicating the percentage of the animation where
@@ -72,7 +72,12 @@ impl KeyframeSelector {
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub struct Keyframe {
     pub selector: KeyframeSelector,
-    pub declarations: Arc<Vec<PropertyDeclaration>>,
+
+    /// `!important` is not allowed in keyframe declarations,
+    /// so the second value of these tuples is always `Importance::Normal`.
+    /// But including them enables `compute_style_for_animation_step` to create a `DeclarationBlock`
+    /// by cloning an `Arc<_>` (incrementing a reference count) rather than re-creating a `Vec<_>`.
+    pub declarations: Arc<Vec<(PropertyDeclaration, Importance)>>,
 }
 
 /// A keyframes step value. This can be a synthetised keyframes animation, that
@@ -82,7 +87,8 @@ pub struct Keyframe {
 #[derive(Debug, Clone, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 pub enum KeyframesStepValue {
-    Declarations(Arc<Vec<PropertyDeclaration>>),
+    /// See `Keyframe::declarations`’s docs about the presence of `Importance`.
+    Declarations(Arc<Vec<(PropertyDeclaration, Importance)>>),
     ComputedValues,
 }
 
@@ -108,7 +114,7 @@ impl KeyframesStep {
            value: KeyframesStepValue) -> Self {
         let declared_timing_function = match value {
             KeyframesStepValue::Declarations(ref declarations) => {
-                declarations.iter().any(|prop_decl| {
+                declarations.iter().any(|&(ref prop_decl, _)| {
                     match *prop_decl {
                         PropertyDeclaration::AnimationTimingFunction(..) => true,
                         _ => false,
@@ -148,8 +154,8 @@ fn get_animated_properties(keyframe: &Keyframe) -> Vec<TransitionProperty> {
     let mut ret = vec![];
     // NB: declarations are already deduplicated, so we don't have to check for
     // it here.
-    for declaration in keyframe.declarations.iter() {
-        if let Some(property) = TransitionProperty::from_declaration(&declaration) {
+    for &(ref declaration, _) in keyframe.declarations.iter() {
+        if let Some(property) = TransitionProperty::from_declaration(declaration) {
             ret.push(property);
         }
     }
@@ -247,7 +253,7 @@ impl<'a> QualifiedRuleParser for KeyframeListParser<'a> {
         let mut iter = DeclarationListParser::new(input, parser);
         while let Some(declaration) = iter.next() {
             match declaration {
-                Ok(d) => declarations.extend(d),
+                Ok(d) => declarations.extend(d.into_iter().map(|d| (d, Importance::Normal))),
                 Err(range) => {
                     let pos = range.start;
                     let message = format!("Unsupported keyframe property declaration: '{}'",

components/style/matching.rs

@@ -14,7 +14,7 @@ use context::{StyleContext, SharedStyleContext};
 use data::PrivateStyleData;
 use dom::{TElement, TNode, TRestyleDamage, UnsafeNode};
 use properties::longhands::display::computed_value as display;
-use properties::{ComputedValues, PropertyDeclaration, cascade};
+use properties::{ComputedValues, cascade};
 use selector_impl::{TheSelectorImpl, PseudoElement};
 use selector_matching::{DeclarationBlock, Stylist};
 use selectors::bloom::BloomFilter;
@@ -118,15 +118,11 @@ impl<'a> ApplicableDeclarationsCacheQuery<'a> {
 
 impl<'a> PartialEq for ApplicableDeclarationsCacheQuery<'a> {
     fn eq(&self, other: &ApplicableDeclarationsCacheQuery<'a>) -> bool {
-        if self.declarations.len() != other.declarations.len() {
-            return false
-        }
-        for (this, other) in self.declarations.iter().zip(other.declarations) {
-            if !arc_ptr_eq(&this.declarations, &other.declarations) {
-                return false
-            }
-        }
-        true
+        self.declarations.len() == other.declarations.len() &&
+        self.declarations.iter().zip(other.declarations).all(|(this, other)| {
+            arc_ptr_eq(&this.mixed_declarations, &other.mixed_declarations) &&
+            this.importance == other.importance
+        })
     }
 }
 impl<'a> Eq for ApplicableDeclarationsCacheQuery<'a> {}
@@ -143,8 +139,9 @@ impl<'a> Hash for ApplicableDeclarationsCacheQuery<'a> {
         for declaration in self.declarations {
             // Each declaration contians an Arc, which is a stable
             // pointer; we use that for hashing and equality.
-            let ptr = &*declaration.declarations as *const Vec<PropertyDeclaration>;
+            let ptr: *const Vec<_> = &*declaration.mixed_declarations;
             ptr.hash(state);
+            declaration.importance.hash(state);
         }
     }
 }