style: Add infrastructure for non-eagerly-cascaded pseudo-elements

This commit also removes StylistWrapper and uses Arc::get_mut instead.

components/layout/context.rs

@@ -108,7 +108,7 @@ pub struct LayoutContext<'a> {
     cached_local_layout_context: Rc<LocalLayoutContext>,
 }
 
-impl<'a> StyleContext<'a, ServoSelectorImpl, ServoComputedValues> for LayoutContext<'a> {
+impl<'a> StyleContext<'a, ServoSelectorImpl> for LayoutContext<'a> {
     fn shared_context(&self) -> &'a SharedStyleContext {
         &self.shared.style_context
     }

components/layout/data.rs

@@ -4,7 +4,8 @@
 
 use construct::ConstructionResult;
 use incremental::RestyleDamage;
-use style::servo::PrivateStyleData;
+use std::sync::Arc;
+use style::servo::{PrecomputedStyleData, PrivateStyleData};
 
 /// Data that layout associates with a node.
 pub struct PrivateLayoutData {
@@ -17,8 +18,9 @@ pub struct PrivateLayoutData {
     /// Description of how to account for recent style changes.
     pub restyle_damage: RestyleDamage,
 
-    /// The current results of flow construction for this node. This is either a flow or a
-    /// `ConstructionItem`. See comments in `construct.rs` for more details.
+    /// The current results of flow construction for this node. This is either a
+    /// flow or a `ConstructionItem`. See comments in `construct.rs` for more
+    /// details.
     pub flow_construction_result: ConstructionResult,
 
     pub before_flow_construction_result: ConstructionResult,
@@ -35,9 +37,9 @@ pub struct PrivateLayoutData {
 
 impl PrivateLayoutData {
     /// Creates new layout data.
-    pub fn new() -> PrivateLayoutData {
+    pub fn new(precomputed_style_data: Arc<PrecomputedStyleData>) -> PrivateLayoutData {
         PrivateLayoutData {
-            style_data: PrivateStyleData::new(),
+            style_data: PrivateStyleData::new(precomputed_style_data),
             restyle_damage: RestyleDamage::empty(),
             flow_construction_result: ConstructionResult::None,
             before_flow_construction_result: ConstructionResult::None,

components/layout/layout_thread.rs

@@ -67,14 +67,13 @@ use std::sync::mpsc::{channel, Sender, Receiver};
 use std::sync::{Arc, Mutex, MutexGuard, RwLock};
 use style::animation::Animation;
 use style::computed_values::{filter, mix_blend_mode};
-use style::context::{ReflowGoal, StylistWrapper};
+use style::context::{ReflowGoal};
 use style::dom::{TDocument, TElement, TNode};
 use style::error_reporting::ParseErrorReporter;
 use style::logical_geometry::LogicalPoint;
 use style::media_queries::{Device, MediaType};
 use style::parallel::WorkQueueData;
 use style::properties::ComputedValues;
-use style::selector_impl::ServoSelectorImpl;
 use style::selector_matching::USER_OR_USER_AGENT_STYLESHEETS;
 use style::servo::{SharedStyleContext, Stylesheet, Stylist};
 use style::stylesheets::CSSRuleIteratorExt;
@@ -107,7 +106,7 @@ pub struct LayoutThreadData {
     pub display_list: Option<Arc<DisplayList>>,
 
     /// Performs CSS selector matching and style resolution.
-    pub stylist: Box<Stylist>,
+    pub stylist: Arc<Stylist>,
 
     /// A queued response for the union of the content boxes of a node.
     pub content_box_response: Rect<Au>,
@@ -421,7 +420,7 @@ impl LayoutThread {
         let font_cache_receiver =
             ROUTER.route_ipc_receiver_to_new_mpsc_receiver(ipc_font_cache_receiver);
 
-        let stylist = box Stylist::new(device);
+        let stylist = Arc::new(Stylist::new(device));
         let outstanding_web_fonts_counter = Arc::new(AtomicUsize::new(0));
         for stylesheet in &*USER_OR_USER_AGENT_STYLESHEETS {
             add_font_face_rules(stylesheet,
@@ -510,7 +509,7 @@ impl LayoutThread {
             style_context: SharedStyleContext {
                 viewport_size: self.viewport_size.clone(),
                 screen_size_changed: screen_size_changed,
-                stylist: StylistWrapper::<ServoSelectorImpl>(&*rw_data.stylist),
+                stylist: rw_data.stylist.clone(),
                 generation: self.generation,
                 goal: goal,
                 new_animations_sender: Mutex::new(self.new_animations_sender.clone()),
@@ -809,7 +808,7 @@ impl LayoutThread {
     /// Sets quirks mode for the document, causing the quirks mode stylesheet to be used.
     fn handle_set_quirks_mode<'a, 'b>(&self, possibly_locked_rw_data: &mut RwData<'a, 'b>) {
         let mut rw_data = possibly_locked_rw_data.lock();
-        rw_data.stylist.set_quirks_mode(true);
+        Arc::get_mut(&mut rw_data.stylist).unwrap().set_quirks_mode(true);
         possibly_locked_rw_data.block(rw_data);
     }
 
@@ -1060,7 +1059,7 @@ impl LayoutThread {
 
         // Calculate the actual viewport as per DEVICE-ADAPT § 6
         let device = Device::new(MediaType::Screen, initial_viewport);
-        rw_data.stylist.set_device(device, &data.document_stylesheets);
+        Arc::get_mut(&mut rw_data.stylist).unwrap().set_device(device, &data.document_stylesheets);
 
         let constraints = rw_data.stylist.viewport_constraints().clone();
         self.viewport_size = match constraints {
@@ -1092,8 +1091,8 @@ impl LayoutThread {
         }
 
         // If the entire flow tree is invalid, then it will be reflowed anyhow.
-        needs_dirtying |= rw_data.stylist.update(&data.document_stylesheets,
-                                                 data.stylesheets_changed);
+        needs_dirtying |= Arc::get_mut(&mut rw_data.stylist).unwrap().update(&data.document_stylesheets,
+                                                                             data.stylesheets_changed);
         let needs_reflow = viewport_size_changed && !needs_dirtying;
         unsafe {
             if needs_dirtying {

components/layout/wrapper.rs

@@ -72,7 +72,7 @@ use style::properties::{ComputedValues, ServoComputedValues};
 use style::properties::{PropertyDeclaration, PropertyDeclarationBlock};
 use style::restyle_hints::ElementSnapshot;
 use style::selector_impl::{NonTSPseudoClass, PseudoElement, ServoSelectorImpl};
-use style::servo::PrivateStyleData;
+use style::servo::{PrecomputedStyleData, PrivateStyleData};
 use url::Url;
 use util::str::is_whitespace;
 
@@ -168,11 +168,11 @@ impl<'ln> TNode for ServoLayoutNode<'ln> {
         OpaqueNodeMethods::from_jsmanaged(unsafe { self.get_jsmanaged() })
     }
 
-    fn initialize_data(self) {
+    fn initialize_data(self, precomputed: &Arc<PrecomputedStyleData>) {
         let has_data = unsafe { self.borrow_data_unchecked().is_some() };
         if !has_data {
             let ptr: NonOpaqueStyleAndLayoutData =
-                Box::into_raw(box RefCell::new(PrivateLayoutData::new()));
+                Box::into_raw(box RefCell::new(PrivateLayoutData::new(precomputed.clone())));
             let opaque = OpaqueStyleAndLayoutData {
                 ptr: unsafe { NonZero::new(ptr as *mut ()) }
             };
@@ -707,9 +707,10 @@ pub trait ThreadSafeLayoutNode : Clone + Copy + Sized + PartialEq {
             })
     }
 
-    // TODO(emilio): Since the ::-details-* pseudos are internal, just affecting one element, and
-    // only changing `display` property when the element `open` attribute changes, this should be
-    // eligible for not being cascaded eagerly, reading the display property from layout instead.
+    // TODO(emilio): Since the ::-details-* pseudos are internal, just affecting
+    // one element, and only changing `display` property when the element `open`
+    // attribute changes, this should be eligible for not being cascaded
+    // eagerly, reading the display property from layout instead.
     #[inline]
     fn get_details_summary_pseudo(&self) -> Option<Self> {
         if self.is_element() &&