Move all *MatchMethods to TElement.

MozReview-Commit-ID: 3V6JIlOVVhw

components/layout/query.rs

@@ -631,14 +631,14 @@ pub fn process_resolved_style_request<'a, N, C>(requested_node: N,
     where N: LayoutNode,
           C: StyleContext<'a>
 {
-    use style::traversal::ensure_node_styled;
+    use style::traversal::ensure_element_styled;
 
     // This node might have display: none, or it's style might be not up to
     // date, so we might need to do style recalc.
     //
     // FIXME(emilio): Is a bit shame we have to do this instead of in style.
     ensure_node_data_initialized(&requested_node);
-    ensure_node_styled(requested_node, style_context);
+    ensure_element_styled(requested_node.as_element().unwrap(), style_context);
 
     let layout_node = requested_node.to_threadsafe();
     let layout_node = match *pseudo {

components/layout/traversal.rs

@@ -99,8 +99,7 @@ impl<'lc, N> DomTraversalContext<N> for RecalcStyleAndConstructFlows<'lc>
             //
             // The bloom filter stuff is all going to be rewritten, so we just hackily duplicate
             // the bloom filter manipulation from recalc_style_at to maintain invariants.
-            let parent = node.parent_node();
+            let parent = node.parent_node().unwrap().as_element();
-            debug_assert!(parent.unwrap().is_element());
             let bf = take_thread_local_bloom_filter(parent, self.root, self.context.shared_context());
             put_thread_local_bloom_filter(bf, &node.to_unsafe(), self.context.shared_context());
 

components/script/layout_wrapper.rs

@@ -133,7 +133,6 @@ impl<'ln> NodeInfo for ServoLayoutNode<'ln> {
 impl<'ln> TNode for ServoLayoutNode<'ln> {
     type ConcreteElement = ServoLayoutElement<'ln>;
     type ConcreteDocument = ServoLayoutDocument<'ln>;
-    type ConcreteRestyleDamage = RestyleDamage;
     type ConcreteChildrenIterator = ServoChildrenIterator<'ln>;
 
     fn to_unsafe(&self) -> UnsafeNode {
@@ -470,6 +469,7 @@ impl<'le> PresentationalHintsSynthetizer for ServoLayoutElement<'le> {
 impl<'le> TElement for ServoLayoutElement<'le> {
     type ConcreteNode = ServoLayoutNode<'le>;
     type ConcreteDocument = ServoLayoutDocument<'le>;
+    type ConcreteRestyleDamage = RestyleDamage;
 
     fn as_node(&self) -> ServoLayoutNode<'le> {
         ServoLayoutNode::from_layout_js(self.element.upcast())

components/style/dom.rs

@@ -106,7 +106,6 @@ impl<T, I> Iterator for LayoutIterator<T> where T: Iterator<Item=I>, I: NodeInfo
 pub trait TNode : Sized + Copy + Clone + NodeInfo {
     type ConcreteElement: TElement<ConcreteNode = Self, ConcreteDocument = Self::ConcreteDocument>;
     type ConcreteDocument: TDocument<ConcreteNode = Self, ConcreteElement = Self::ConcreteElement>;
-    type ConcreteRestyleDamage: TRestyleDamage;
     type ConcreteChildrenIterator: Iterator<Item = Self>;
 
     fn to_unsafe(&self) -> UnsafeNode;
@@ -249,6 +248,7 @@ pub trait PresentationalHintsSynthetizer {
 pub trait TElement : PartialEq + Debug + Sized + Copy + Clone + ElementExt + PresentationalHintsSynthetizer {
     type ConcreteNode: TNode<ConcreteElement = Self, ConcreteDocument = Self::ConcreteDocument>;
     type ConcreteDocument: TDocument<ConcreteNode = Self::ConcreteNode, ConcreteElement = Self>;
+    type ConcreteRestyleDamage: TRestyleDamage;
 
     fn as_node(&self) -> Self::ConcreteNode;
 
@@ -260,7 +260,7 @@ pub trait TElement : PartialEq + Debug + Sized + Copy + Clone + ElementExt + Pre
     fn attr_equals(&self, namespace: &Namespace, attr: &Atom, value: &Atom) -> bool;
 
     /// Set the restyle damage field.
-    fn set_restyle_damage(self, damage: <Self::ConcreteNode as TNode>::ConcreteRestyleDamage);
+    fn set_restyle_damage(self, damage: Self::ConcreteRestyleDamage);
 
     /// XXX: It's a bit unfortunate we need to pass the current computed values
     /// as an argument here, but otherwise Servo would crash due to double
@@ -268,8 +268,7 @@ pub trait TElement : PartialEq + Debug + Sized + Copy + Clone + ElementExt + Pre
     fn existing_style_for_restyle_damage<'a>(&'a self,
                                              current_computed_values: Option<&'a Arc<ComputedValues>>,
                                              pseudo: Option<&PseudoElement>)
-        -> Option<&'a <<Self::ConcreteNode as TNode>::ConcreteRestyleDamage as TRestyleDamage>
+        -> Option<&'a <Self::ConcreteRestyleDamage as TRestyleDamage> ::PreExistingComputedValues>;
-                      ::PreExistingComputedValues>;
 
     /// Properly marks nodes as dirty in response to restyle hints.
     fn note_restyle_hint<C: DomTraversalContext<Self::ConcreteNode>>(&self, hint: RestyleHint) {

components/style/gecko/wrapper.rs

@@ -160,7 +160,6 @@ impl<'ln> NodeInfo for GeckoNode<'ln> {
 impl<'ln> TNode for GeckoNode<'ln> {
     type ConcreteDocument = GeckoDocument<'ln>;
     type ConcreteElement = GeckoElement<'ln>;
-    type ConcreteRestyleDamage = GeckoRestyleDamage;
     type ConcreteChildrenIterator = GeckoChildrenIterator<'ln>;
 
     fn to_unsafe(&self) -> UnsafeNode {
@@ -399,6 +398,7 @@ lazy_static! {
 impl<'le> TElement for GeckoElement<'le> {
     type ConcreteNode = GeckoNode<'le>;
     type ConcreteDocument = GeckoDocument<'le>;
+    type ConcreteRestyleDamage = GeckoRestyleDamage;
 
     fn as_node(&self) -> Self::ConcreteNode {
         unsafe { GeckoNode(&*(self.0 as *const _ as *const RawGeckoNode)) }

components/style/matching.rs

@@ -12,12 +12,12 @@ use cache::{LRUCache, SimpleHashCache};
 use cascade_info::CascadeInfo;
 use context::{SharedStyleContext, StyleContext};
 use data::{NodeStyles, PseudoStyles};
-use dom::{NodeInfo, TElement, TNode, TRestyleDamage, UnsafeNode};
+use dom::{TElement, TNode, TRestyleDamage, UnsafeNode};
 use properties::{CascadeFlags, ComputedValues, SHAREABLE, cascade};
 use properties::longhands::display::computed_value as display;
 use selector_impl::{PseudoElement, TheSelectorImpl};
 use selector_matching::{ApplicableDeclarationBlock, Stylist};
-use selectors::{Element, MatchAttr};
+use selectors::MatchAttr;
 use selectors::bloom::BloomFilter;
 use selectors::matching::{AFFECTED_BY_PSEUDO_ELEMENTS, MatchingReason, StyleRelations};
 use sink::ForgetfulSink;
@@ -497,7 +497,7 @@ struct CascadeBooleans {
     animate: bool,
 }
 
-trait PrivateMatchMethods: TNode {
+trait PrivateMatchMethods: TElement {
     /// Actually cascades style for a node or a pseudo-element of a node.
     ///
     /// Note that animations only apply to nodes or ::before or ::after
@@ -521,7 +521,7 @@ trait PrivateMatchMethods: TNode {
         // and the cache would not be effective anyway.
         // This also works around the test failures at
         // https://github.com/servo/servo/pull/13459#issuecomment-250717584
-        let has_style_attribute = self.as_element().map_or(false, |e| e.style_attribute().is_some());
+        let has_style_attribute = self.style_attribute().is_some();
         cacheable = cacheable && !has_style_attribute;
 
         let mut cascade_info = CascadeInfo::new();
@@ -556,7 +556,7 @@ trait PrivateMatchMethods: TNode {
                         cascade_flags)
             }
         };
-        cascade_info.finish(self);
+        cascade_info.finish(&self.as_node());
 
         cacheable = cacheable && is_cacheable;
 
@@ -564,7 +564,7 @@ trait PrivateMatchMethods: TNode {
 
         if booleans.animate {
             let new_animations_sender = &context.local_context().new_animations_sender;
-            let this_opaque = self.opaque();
+            let this_opaque = self.as_node().opaque();
             // Trigger any present animations if necessary.
             let mut animations_started = animation::maybe_start_animations(
                 &shared_context,
@@ -579,7 +579,7 @@ trait PrivateMatchMethods: TNode {
                     animation::start_transitions_if_applicable(
                         new_animations_sender,
                         this_opaque,
-                        self.to_unsafe(),
+                        self.as_node().to_unsafe(),
                         &**style,
                         &mut this_style,
                         &shared_context.timer);
@@ -601,7 +601,7 @@ trait PrivateMatchMethods: TNode {
                                      context: &SharedStyleContext,
                                      style: &mut Arc<ComputedValues>) -> bool {
         // Finish any expired transitions.
-        let this_opaque = self.opaque();
+        let this_opaque = self.as_node().opaque();
         let had_animations_to_expire =
             animation::complete_expired_transitions(this_opaque, style, context);
 
@@ -636,18 +636,11 @@ trait PrivateMatchMethods: TNode {
 
         had_animations_to_expire || had_running_animations
     }
-}
 
-impl<N: TNode> PrivateMatchMethods for N {}
-
-trait PrivateElementMatchMethods: TElement {
     fn share_style_with_candidate_if_possible(&self,
-                                              parent_node: Self::ConcreteNode,
                                               shared_context: &SharedStyleContext,
                                               candidate: &mut StyleSharingCandidate)
                                               -> Result<Arc<ComputedValues>, CacheMiss> {
-        debug_assert!(parent_node.is_element());
-
         let candidate_element = unsafe {
             Self::ConcreteNode::from_unsafe(&candidate.node).as_element().unwrap()
         };
@@ -657,9 +650,9 @@ trait PrivateElementMatchMethods: TElement {
     }
 }
 
-impl<E: TElement> PrivateElementMatchMethods for E {}
+impl<E: TElement> PrivateMatchMethods for E {}
 
-pub trait ElementMatchMethods : TElement {
+pub trait MatchMethods : TElement {
     fn match_element(&self,
                      stylist: &Stylist,
                      parent_bf: Option<&BloomFilter>,
@@ -703,9 +696,8 @@ pub trait ElementMatchMethods : TElement {
     unsafe fn share_style_if_possible(&self,
                                       style_sharing_candidate_cache:
                                         &mut StyleSharingCandidateCache,
-                                      shared_context: &SharedStyleContext,
+                                      shared_context: &SharedStyleContext)
-                                      parent: Option<Self::ConcreteNode>)
+                                      -> StyleSharingResult<Self::ConcreteRestyleDamage> {
-                                      -> StyleSharingResult<<Self::ConcreteNode as TNode>::ConcreteRestyleDamage> {
         if opts::get().disable_share_style_cache {
             return StyleSharingResult::CannotShare
         }
@@ -718,16 +710,9 @@ pub trait ElementMatchMethods : TElement {
             return StyleSharingResult::CannotShare
         }
 
-        let parent = match parent {
-            Some(parent) if parent.is_element() => parent,
-            _ => return StyleSharingResult::CannotShare,
-        };
-
         let mut should_clear_cache = false;
         for (i, &mut (ref mut candidate, ())) in style_sharing_candidate_cache.iter_mut().enumerate() {
-            let sharing_result = self.share_style_with_candidate_if_possible(parent,
+            let sharing_result = self.share_style_with_candidate_if_possible(shared_context, candidate);
-                                                                             shared_context,
-                                                                             candidate);
             match sharing_result {
                 Ok(shared_style) => {
                     // Yay, cache hit. Share the style.
@@ -741,12 +726,10 @@ pub trait ElementMatchMethods : TElement {
                     let damage =
                         match self.existing_style_for_restyle_damage(data.previous_styles().map(|x| &x.primary), None) {
                             Some(ref source) => {
-                                <<Self as TElement>::ConcreteNode as TNode>
+                                Self::ConcreteRestyleDamage::compute(source, &shared_style)
-                                ::ConcreteRestyleDamage::compute(source, &shared_style)
                             }
                             None => {
-                                <<Self as TElement>::ConcreteNode as TNode>
+                                Self::ConcreteRestyleDamage::rebuild_and_reflow()
-                                ::ConcreteRestyleDamage::rebuild_and_reflow()
                             }
                         };
 
@@ -788,11 +771,7 @@ pub trait ElementMatchMethods : TElement {
 
         StyleSharingResult::CannotShare
     }
-}
 
-impl<E: TElement> ElementMatchMethods for E {}
-
-pub trait MatchMethods : TNode {
     // The below two functions are copy+paste because I can't figure out how to
     // write a function which takes a generic function. I don't think it can
     // be done.
@@ -816,29 +795,23 @@ pub trait MatchMethods : TNode {
     /// Therefore, each node must have its matching selectors inserted _after_
     /// its own selector matching and _before_ its children start.
     fn insert_into_bloom_filter(&self, bf: &mut BloomFilter) {
-        // Only elements are interesting.
+        bf.insert(&*self.get_local_name());
-        if let Some(element) = self.as_element() {
+        bf.insert(&*self.get_namespace());
-            bf.insert(&*element.get_local_name());
+        self.get_id().map(|id| bf.insert(&id));
-            bf.insert(&*element.get_namespace());
-            element.get_id().map(|id| bf.insert(&id));
 
         // TODO: case-sensitivity depends on the document type and quirks mode
-            element.each_class(|class| bf.insert(class));
+        self.each_class(|class| bf.insert(class));
-        }
     }
 
     /// After all the children are done css selector matching, this must be
     /// called to reset the bloom filter after an `insert`.
     fn remove_from_bloom_filter(&self, bf: &mut BloomFilter) {
-        // Only elements are interesting.
+        bf.remove(&*self.get_local_name());
-        if let Some(element) = self.as_element() {
+        bf.remove(&*self.get_namespace());
-            bf.remove(&*element.get_local_name());
+        self.get_id().map(|id| bf.remove(&id));
-            bf.remove(&*element.get_namespace());
-            element.get_id().map(|id| bf.remove(&id));
 
         // TODO: case-sensitivity depends on the document type and quirks mode
-            element.each_class(|class| bf.remove(class));
+        self.each_class(|class| bf.remove(class));
-        }
     }
 
     fn compute_restyle_damage(&self,
@@ -847,7 +820,7 @@ pub trait MatchMethods : TNode {
                               pseudo: Option<&PseudoElement>)
                               -> Self::ConcreteRestyleDamage
     {
-        match self.as_element().unwrap().existing_style_for_restyle_damage(old_style, pseudo) {
+        match self.existing_style_for_restyle_damage(old_style, pseudo) {
             Some(ref source) => {
                 Self::ConcreteRestyleDamage::compute(source,
                                                      new_style)
@@ -890,23 +863,12 @@ pub trait MatchMethods : TNode {
         where Ctx: StyleContext<'a>
     {
         // Get our parent's style.
-        let parent_data = parent.as_ref().map(|x| x.borrow_data().unwrap());
+        let parent_as_node = parent.map(|x| x.as_node());
+        let parent_data = parent_as_node.as_ref().map(|x| x.borrow_data().unwrap());
         let parent_style = parent_data.as_ref().map(|x| &x.current_styles().primary);
 
-        // In the case we're styling a text node, we don't need to compute the
+        let node = self.as_node();
-        // restyle damage, since it's a subset of the restyle damage of the
+        let mut data = node.begin_styling();
-        // parent.
-        //
-        // In Gecko, we're done, we don't need anything else from text nodes.
-        //
-        // In Servo, this is also true, since text nodes generate UnscannedText
-        // fragments, which aren't repairable by incremental layout.
-        if self.is_text_node() {
-            self.style_text_node(ComputedValues::style_for_child_text_node(parent_style.clone().unwrap()));
-            return RestyleResult::Continue;
-        }
-
-        let mut data = self.begin_styling();
         let mut new_styles;
 
         let mut applicable_declarations_cache =
@@ -944,8 +906,8 @@ pub trait MatchMethods : TNode {
                                                         context, applicable_declarations,
                                                         &mut applicable_declarations_cache);
 
-            self.set_can_be_fragmented(parent.map_or(false, |p| {
+            self.as_node().set_can_be_fragmented(parent.map_or(false, |p| {
-                p.can_be_fragmented() ||
+                p.as_node().can_be_fragmented() ||
                 parent_style.unwrap().is_multicol()
             }));
 
@@ -955,7 +917,7 @@ pub trait MatchMethods : TNode {
         data.finish_styling(new_styles);
         // Drop the mutable borrow early, since Servo's set_restyle_damage also borrows.
         mem::drop(data);
-        self.as_element().unwrap().set_restyle_damage(damage);
+        self.set_restyle_damage(damage);
 
         restyle_result
     }
@@ -1006,7 +968,7 @@ pub trait MatchMethods : TNode {
         let no_damage = Self::ConcreteRestyleDamage::empty();
 
         debug_assert!(new_pseudos.is_empty());
-        <Self::ConcreteElement as MatchAttr>::Impl::each_eagerly_cascaded_pseudo_element(|pseudo| {
+        <Self as MatchAttr>::Impl::each_eagerly_cascaded_pseudo_element(|pseudo| {
             let applicable_declarations_for_this_pseudo =
                 applicable_declarations.per_pseudo.get(&pseudo).unwrap();
 
@@ -1018,8 +980,7 @@ pub trait MatchMethods : TNode {
 
             if has_declarations {
                 // We have declarations, so we need to cascade. Compute parameters.
-                let animate = <Self::ConcreteElement as MatchAttr>::Impl
+                let animate = <Self as MatchAttr>::Impl::pseudo_is_before_or_after(&pseudo);
-                                ::pseudo_is_before_or_after(&pseudo);
                 let cacheable = if animate && old_pseudo_style.is_some() {
                     // Update animations before the cascade. This may modify
                     // the value of old_pseudo_style.
@@ -1064,4 +1025,4 @@ pub trait MatchMethods : TNode {
     }
 }
 
-impl<N: TNode> MatchMethods for N {}
+impl<E: TElement> MatchMethods for E {}

components/style/traversal.rs

@@ -8,7 +8,7 @@ use atomic_refcell::AtomicRefCell;
 use context::{LocalStyleContext, SharedStyleContext, StyleContext};
 use data::NodeData;
 use dom::{NodeInfo, OpaqueNode, StylingMode, TElement, TNode, UnsafeNode};
-use matching::{ApplicableDeclarations, ElementMatchMethods, MatchMethods, StyleSharingResult};
+use matching::{ApplicableDeclarations, MatchMethods, StyleSharingResult};
 use selectors::bloom::BloomFilter;
 use selectors::matching::StyleRelations;
 use std::cell::RefCell;
@@ -62,13 +62,13 @@ thread_local!(
 ///
 /// If one does not exist, a new one will be made for you. If it is out of date,
 /// it will be cleared and reused.
-pub fn take_thread_local_bloom_filter<N>(parent_node: Option<N>,
+pub fn take_thread_local_bloom_filter<E>(parent_element: Option<E>,
                                          root: OpaqueNode,
                                          context: &SharedStyleContext)
                                          -> Box<BloomFilter>
-                                         where N: TNode {
+                                         where E: TElement {
     STYLE_BLOOM.with(|style_bloom| {
-        match (parent_node, style_bloom.borrow_mut().take()) {
+        match (parent_element, style_bloom.borrow_mut().take()) {
             // Root node. Needs new bloom filter.
             (None,     _  ) => {
                 debug!("[{}] No parent, but new bloom filter!", tid());
@@ -82,7 +82,7 @@ pub fn take_thread_local_bloom_filter<N>(parent_node: Option<N>,
             }
             // Found cached bloom filter.
             (Some(parent), Some((mut bloom_filter, old_node, old_generation))) => {
-                if old_node == parent.to_unsafe() &&
+                if old_node == parent.as_node().to_unsafe() &&
                     old_generation == context.generation {
                     // Hey, the cached parent is our parent! We can reuse the bloom filter.
                     debug!("[{}] Parent matches (={}). Reusing bloom filter.", tid(), old_node.0);
@@ -108,17 +108,17 @@ pub fn put_thread_local_bloom_filter(bf: Box<BloomFilter>, unsafe_node: &UnsafeN
 }
 
 /// "Ancestors" in this context is inclusive of ourselves.
-fn insert_ancestors_into_bloom_filter<N>(bf: &mut Box<BloomFilter>,
+fn insert_ancestors_into_bloom_filter<E>(bf: &mut Box<BloomFilter>,
-                                         mut n: N,
+                                         mut el: E,
                                          root: OpaqueNode)
-                                         where N: TNode {
+                                         where E: TElement {
     debug!("[{}] Inserting ancestors.", tid());
     let mut ancestors = 0;
     loop {
         ancestors += 1;
 
-        n.insert_into_bloom_filter(&mut **bf);
+        el.insert_into_bloom_filter(&mut **bf);
-        n = match n.layout_parent_node(root) {
+        el = match el.as_node().layout_parent_node(root).and_then(|x| x.as_element()) {
             None => break,
             Some(p) => p,
         };
@@ -149,7 +149,7 @@ pub fn remove_from_bloom_filter<'a, N, C>(context: &C, root: OpaqueNode, node: N
         }
         Some(parent) => {
             // Otherwise, put it back, but remove this node.
-            node.remove_from_bloom_filter(&mut *bf);
+            node.as_element().map(|x| x.remove_from_bloom_filter(&mut *bf));
             let unsafe_parent = parent.to_unsafe();
             put_thread_local_bloom_filter(bf, &unsafe_parent, &context.shared_context());
         },
@@ -213,20 +213,20 @@ pub fn relations_are_shareable(relations: &StyleRelations) -> bool {
                           AFFECTED_BY_PRESENTATIONAL_HINTS)
 }
 
-pub fn ensure_node_styled<'a, N, C>(node: N,
+pub fn ensure_element_styled<'a, E, C>(element: E,
                                        context: &'a C)
-    where N: TNode,
+    where E: TElement,
           C: StyleContext<'a>
 {
     let mut display_none = false;
-    ensure_node_styled_internal(node, context, &mut display_none);
+    ensure_element_styled_internal(element, context, &mut display_none);
 }
 
 #[allow(unsafe_code)]
-fn ensure_node_styled_internal<'a, N, C>(node: N,
+fn ensure_element_styled_internal<'a, E, C>(element: E,
                                             context: &'a C,
                                             parents_had_display_none: &mut bool)
-    where N: TNode,
+    where E: TElement,
           C: StyleContext<'a>
 {
     use properties::longhands::display::computed_value as display;
@@ -238,13 +238,9 @@ fn ensure_node_styled_internal<'a, N, C>(node: N,
     // This means potentially a bit of wasted work (usually not much). We could
     // add a flag at the node at which point we stopped the traversal to know
     // where should we stop, but let's not add that complication unless needed.
-    let parent = match node.parent_node() {
+    let parent = element.parent_element();
-        Some(parent) if parent.is_element() => Some(parent),
-        _ => None,
-    };
-
     if let Some(parent) = parent {
-        ensure_node_styled_internal(parent, context, parents_had_display_none);
+        ensure_element_styled_internal(parent, context, parents_had_display_none);
     }
 
     // Common case: our style is already resolved and none of our ancestors had
@@ -252,6 +248,7 @@ fn ensure_node_styled_internal<'a, N, C>(node: N,
     //
     // We only need to mark whether we have display none, and forget about it,
     // our style is up to date.
+    let node = element.as_node();
     if let Some(data) = node.borrow_data() {
         if let Some(style) = data.get_current_styles().map(|x| &x.primary) {
             if !*parents_had_display_none {
@@ -268,16 +265,14 @@ fn ensure_node_styled_internal<'a, N, C>(node: N,
     // probably not necessary since we're likely to be matching only a few
     // nodes, at best.
     let mut applicable_declarations = ApplicableDeclarations::new();
-    if let Some(element) = node.as_element() {
     let stylist = &context.shared_context().stylist;
 
     element.match_element(&**stylist,
                           None,
                           &mut applicable_declarations);
-    }
 
     unsafe {
-        node.cascade_node(context, parent, &applicable_declarations);
+        element.cascade_node(context, parent, &applicable_declarations);
     }
 }
 
@@ -291,34 +286,21 @@ pub fn recalc_style_at<'a, E, C, D>(context: &'a C,
           C: StyleContext<'a>,
           D: DomTraversalContext<E::ConcreteNode>
 {
-    let node = element.as_node();
-
-    // Get the parent node.
-    let parent_opt = match node.parent_node() {
-        Some(parent) if parent.is_element() => Some(parent),
-        _ => None,
-    };
-
     // Get the style bloom filter.
-    let mut bf = take_thread_local_bloom_filter(parent_opt, root, context.shared_context());
+    let mut bf = take_thread_local_bloom_filter(element.parent_element(), root, context.shared_context());
 
     let mut restyle_result = RestyleResult::Continue;
-    let mode = node.styling_mode();
+    let mode = element.as_node().styling_mode();
     debug_assert!(mode != StylingMode::Stop, "Parent should not have enqueued us");
     if mode != StylingMode::Traverse {
         // Check to see whether we can share a style with someone.
         let style_sharing_candidate_cache =
             &mut context.local_context().style_sharing_candidate_cache.borrow_mut();
 
-        let sharing_result = match node.as_element() {
+        let sharing_result = if element.parent_element().is_none() {
-            Some(element) => {
+            StyleSharingResult::CannotShare
-                unsafe {
+        } else {
-                    element.share_style_if_possible(style_sharing_candidate_cache,
+            unsafe { element.share_style_if_possible(style_sharing_candidate_cache, context.shared_context()) }
-                                                    context.shared_context(),
-                                                    parent_opt.clone())
-                }
-            },
-            None => StyleSharingResult::CannotShare,
         };
 
         // Otherwise, match and cascade selectors.
@@ -327,8 +309,7 @@ pub fn recalc_style_at<'a, E, C, D>(context: &'a C,
                 let mut applicable_declarations = ApplicableDeclarations::new();
 
                 let relations;
-                let shareable_element = match node.as_element() {
+                let shareable_element = {
-                    Some(element) => {
                     if opts::get().style_sharing_stats {
                         STYLE_SHARING_CACHE_MISSES.fetch_add(1, Ordering::Relaxed);
                     }
@@ -347,17 +328,12 @@ pub fn recalc_style_at<'a, E, C, D>(context: &'a C,
                     } else {
                         None
                     }
-                    },
-                    None => {
-                        relations = StyleRelations::empty();
-                        None
-                    },
                 };
 
                 // Perform the CSS cascade.
                 unsafe {
-                    restyle_result = node.cascade_node(context,
+                    restyle_result = element.cascade_node(context,
-                                                       parent_opt,
+                                                          element.parent_element(),
                                                           &applicable_declarations);
                 }
 
@@ -372,7 +348,7 @@ pub fn recalc_style_at<'a, E, C, D>(context: &'a C,
                     STYLE_SHARING_CACHE_HITS.fetch_add(1, Ordering::Relaxed);
                 }
                 style_sharing_candidate_cache.touch(index);
-                node.as_element().unwrap().set_restyle_damage(damage);
+                element.set_restyle_damage(damage);
             }
         }
     }
@@ -381,7 +357,7 @@ pub fn recalc_style_at<'a, E, C, D>(context: &'a C,
     // processing. The eventual algorithm we're designing does this in a more granular
     // fashion.
     if mode == StylingMode::Restyle && restyle_result == RestyleResult::Continue {
-        for kid in node.children() {
+        for kid in element.as_node().children() {
             let mut data = D::ensure_node_data(&kid).borrow_mut();
             if kid.is_text_node() {
                 data.ensure_restyle_data();
@@ -394,12 +370,12 @@ pub fn recalc_style_at<'a, E, C, D>(context: &'a C,
         }
     }
 
-    let unsafe_layout_node = node.to_unsafe();
+    let unsafe_layout_node = element.as_node().to_unsafe();
 
     // Before running the children, we need to insert our nodes into the bloom
     // filter.
     debug!("[{}] + {:X}", tid(), unsafe_layout_node.0);
-    node.insert_into_bloom_filter(&mut *bf);
+    element.insert_into_bloom_filter(&mut *bf);
 
     // NB: flow construction updates the bloom filter on the way up.
     put_thread_local_bloom_filter(bf, &unsafe_layout_node, context.shared_context());