style: Make XBL / Shadow DOM use something more light-weight than a Stylist.

It's just a struct aggregating stylesheets + CascadeData, with a quirks_mode
parameter because XBL sucks so bad.

Bug: 1436059
Reviewed-by: xidorn
MozReview-Commit-ID: 7q99tSNXo0K

components/style/author_styles.rs

@@ -0,0 +1,91 @@
+/* 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/. */
+
+//! A set of author stylesheets and their computed representation, such as the
+//! ones used for ShadowRoot and XBL.
+
+use context::QuirksMode;
+use dom::TElement;
+#[cfg(feature = "gecko")]
+use gecko_bindings::sugar::ownership::{HasBoxFFI, HasFFI, HasSimpleFFI};
+use invalidation::media_queries::ToMediaListKey;
+use media_queries::Device;
+use shared_lock::SharedRwLockReadGuard;
+use stylesheet_set::AuthorStylesheetSet;
+use stylesheets::StylesheetInDocument;
+use stylist::CascadeData;
+
+
+/// A set of author stylesheets and their computed representation, such as the
+/// ones used for ShadowRoot and XBL.
+pub struct AuthorStyles<S>
+where
+    S: StylesheetInDocument + PartialEq + 'static,
+{
+    /// The sheet collection, which holds the sheet pointers, the invalidations,
+    /// and all that stuff.
+    pub stylesheets: AuthorStylesheetSet<S>,
+    /// The actual cascade data computed from the stylesheets.
+    pub data: CascadeData,
+    /// The quirks mode of the last stylesheet flush, used because XBL sucks and
+    /// we should really fix it, see bug 1406875.
+    pub quirks_mode: QuirksMode,
+}
+
+impl<S> AuthorStyles<S>
+where
+    S: StylesheetInDocument + PartialEq + 'static,
+{
+    /// Create an empty AuthorStyles.
+    #[inline]
+    pub fn new() -> Self {
+        Self {
+            stylesheets: AuthorStylesheetSet::new(),
+            data: CascadeData::new(),
+            quirks_mode: QuirksMode::NoQuirks,
+        }
+    }
+
+    /// Flush the pending sheet changes, updating `data` as appropriate.
+    ///
+    /// TODO(emilio): Need a host element and a snapshot map to do invalidation
+    /// properly.
+    #[inline]
+    pub fn flush<E>(
+        &mut self,
+        device: &Device,
+        quirks_mode: QuirksMode,
+        guard: &SharedRwLockReadGuard,
+    )
+    where
+        E: TElement,
+        S: ToMediaListKey,
+    {
+        let flusher = self.stylesheets.flush::<E>(
+            /* host = */ None,
+            /* snapshot_map = */ None,
+        );
+
+        if flusher.sheets.dirty() {
+            self.quirks_mode = quirks_mode;
+        }
+
+        // Ignore OOM.
+        let _ = self.data.rebuild(
+            device,
+            quirks_mode,
+            flusher.sheets,
+            guard,
+        );
+    }
+}
+
+#[cfg(feature = "gecko")]
+unsafe impl HasFFI for AuthorStyles<::gecko::data::GeckoStyleSheet> {
+    type FFIType = ::gecko_bindings::bindings::RawServoAuthorStyles;
+}
+#[cfg(feature = "gecko")]
+unsafe impl HasSimpleFFI for AuthorStyles<::gecko::data::GeckoStyleSheet> {}
+#[cfg(feature = "gecko")]
+unsafe impl HasBoxFFI for AuthorStyles<::gecko::data::GeckoStyleSheet> {}

components/style/dom.rs

@@ -754,7 +754,7 @@ pub trait TElement
     fn each_xbl_cascade_data<'a, F>(&self, _: F) -> bool
     where
         Self: 'a,
-        F: FnMut(AtomicRef<'a, CascadeData>, QuirksMode),
+        F: FnMut(&'a CascadeData, QuirksMode),
     {
         false
     }
@@ -766,7 +766,7 @@ pub trait TElement
     fn each_applicable_non_document_style_rule_data<'a, F>(&self, mut f: F) -> bool
     where
         Self: 'a,
-        F: FnMut(AtomicRef<'a, CascadeData>, QuirksMode),
+        F: FnMut(&'a CascadeData, QuirksMode),
     {
         let cut_off_inheritance = self.each_xbl_cascade_data(&mut f);
 

components/style/gecko/wrapper.rs

@@ -17,13 +17,14 @@
 use CaseSensitivityExt;
 use app_units::Au;
 use applicable_declarations::ApplicableDeclarationBlock;
-use atomic_refcell::{AtomicRefCell, AtomicRef, AtomicRefMut};
+use atomic_refcell::{AtomicRefCell, AtomicRefMut};
+use author_styles::AuthorStyles;
 use context::{QuirksMode, SharedStyleContext, PostAnimationTasks, UpdateAnimationsTasks};
 use data::ElementData;
 use dom::{LayoutIterator, NodeInfo, OpaqueNode, TElement, TDocument, TNode};
 use element_state::{ElementState, DocumentState};
 use font_metrics::{FontMetrics, FontMetricsProvider, FontMetricsQueryResult};
-use gecko::data::PerDocumentStyleData;
+use gecko::data::GeckoStyleSheet;
 use gecko::global_style_data::GLOBAL_STYLE_DATA;
 use gecko::selector_parser::{SelectorImpl, NonTSPseudoClass, PseudoElement};
 use gecko::snapshot_helpers;
@@ -431,20 +432,19 @@ impl<'lb> GeckoXBLBinding<'lb> {
 
     fn each_xbl_cascade_data<F>(&self, f: &mut F)
     where
-        F: FnMut(AtomicRef<'lb, CascadeData>, QuirksMode),
+        F: FnMut(&'lb CascadeData, QuirksMode),
     {
         if let Some(base) = self.base_binding() {
             base.each_xbl_cascade_data(f);
         }
 
-        let raw_data = unsafe {
-            bindings::Gecko_XBLBinding_GetRawServoStyleSet(self.0)
+        let data = unsafe {
+            bindings::Gecko_XBLBinding_GetRawServoStyles(self.0)
         };
 
-        if let Some(raw_data) = raw_data {
-            let data = PerDocumentStyleData::from_ffi(&*raw_data).borrow();
-            let quirks_mode = data.stylist.quirks_mode();
-            f(AtomicRef::map(data, |d| d.stylist.author_cascade_data()), quirks_mode);
+        if let Some(data) = data {
+            let data: &'lb _ = AuthorStyles::<GeckoStyleSheet>::from_ffi(data);
+            f(&data.data, data.quirks_mode)
         }
     }
 }
@@ -1378,7 +1378,7 @@ impl<'le> TElement for GeckoElement<'le> {
     fn each_xbl_cascade_data<'a, F>(&self, mut f: F) -> bool
     where
         'le: 'a,
-        F: FnMut(AtomicRef<'a, CascadeData>, QuirksMode),
+        F: FnMut(&'a CascadeData, QuirksMode),
     {
         // Walk the binding scope chain, starting with the binding attached to
         // our content, up till we run out of scopes or we get cut off.

components/style/gecko_bindings/sugar/ns_t_array.rs

@@ -36,6 +36,7 @@ impl<T> nsTArray<T> {
         debug_assert!(!self.mBuffer.is_null());
         unsafe { mem::transmute(self.mBuffer) }
     }
+
     // unsafe, since header may be in shared static or something
     unsafe fn header_mut<'a>(&'a mut self) -> &'a mut nsTArrayHeader {
         debug_assert!(!self.mBuffer.is_null());

components/style/invalidation/element/state_and_attributes.rs

@@ -6,7 +6,6 @@
 //! changes.
 
 use Atom;
-use atomic_refcell::AtomicRef;
 use context::{QuirksMode, SharedStyleContext};
 use data::ElementData;
 use dom::TElement;
@@ -57,7 +56,7 @@ where
 /// changes.
 pub struct StateAndAttrInvalidationProcessor<'a, 'b: 'a, E: TElement> {
     shared_context: &'a SharedStyleContext<'b>,
-    shadow_rule_datas: &'a [(AtomicRef<'b, CascadeData>, QuirksMode)],
+    shadow_rule_datas: &'a [(&'b CascadeData, QuirksMode)],
     cut_off_inheritance: bool,
     element: E,
     data: &'a mut ElementData,
@@ -68,7 +67,7 @@ impl<'a, 'b: 'a, E: TElement> StateAndAttrInvalidationProcessor<'a, 'b, E> {
     /// Creates a new StateAndAttrInvalidationProcessor.
     pub fn new(
         shared_context: &'a SharedStyleContext<'b>,
-        shadow_rule_datas: &'a [(AtomicRef<'b, CascadeData>, QuirksMode)],
+        shadow_rule_datas: &'a [(&'b CascadeData, QuirksMode)],
         cut_off_inheritance: bool,
         element: E,
         data: &'a mut ElementData,

components/style/lib.rs

@@ -87,6 +87,7 @@ mod macros;
 pub mod applicable_declarations;
 #[allow(missing_docs)] // TODO.
 #[cfg(feature = "servo")] pub mod attr;
+pub mod author_styles;
 pub mod bezier;
 pub mod bloom;
 pub mod context;

components/style/stylesheet_set.rs

@@ -583,6 +583,20 @@ impl<S> AuthorStylesheetSet<S>
 where
     S: StylesheetInDocument + PartialEq + 'static,
 {
+    /// Create a new empty AuthorStylesheetSet.
+    #[inline]
+    pub fn new() -> Self {
+        Self {
+            collection: Default::default(),
+            invalidations: StylesheetInvalidationSet::new(),
+        }
+    }
+
+    /// Whether anything has changed since the last time this was flushed.
+    pub fn dirty(&self) -> bool {
+        self.collection.dirty
+    }
+
     fn collection_for(
         &mut self,
         _sheet: &S,
@@ -593,6 +607,17 @@ where
 
     sheet_set_methods!("AuthorStylesheetSet");
 
+    /// Iterate over the list of stylesheets.
+    pub fn iter(&self) -> StylesheetCollectionIterator<S> {
+        self.collection.iter()
+    }
+
+    /// Mark the sheet set dirty, as appropriate.
+    pub fn force_dirty(&mut self) {
+        self.invalidations.invalidate_fully();
+        self.collection.set_data_validity_at_least(DataValidity::FullyInvalid);
+    }
+
     /// Flush the stylesheets for this author set.
     ///
     /// `host` is the root of the affected subtree, like the shadow host, for

components/style/stylist.rs

@@ -1983,7 +1983,8 @@ pub struct CascadeData {
 }
 
 impl CascadeData {
-    fn new() -> Self {
+    /// Creates an empty `CascadeData`.
+    pub fn new() -> Self {
         Self {
             normal_rules: ElementAndPseudoRules::default(),
             slotted_rules: None,
@@ -2005,7 +2006,7 @@ impl CascadeData {
 
     /// Rebuild the cascade data from a given SheetCollection, incrementally if
     /// possible.
-    fn rebuild<'a, S>(
+    pub fn rebuild<'a, S>(
         &mut self,
         device: &Device,
         quirks_mode: QuirksMode,
@@ -2281,7 +2282,7 @@ impl CascadeData {
 
     /// Returns whether all the media-feature affected values matched before and
     /// match now in the given stylesheet.
-    fn media_feature_affected_matches<S>(
+    pub fn media_feature_affected_matches<S>(
         &self,
         stylesheet: &S,
         guard: &SharedRwLockReadGuard,

ports/geckolib/glue.rs

@@ -17,6 +17,7 @@ use std::iter;
 use std::mem;
 use std::ptr;
 use style::applicable_declarations::ApplicableDeclarationBlock;
+use style::author_styles::AuthorStyles;
 use style::context::{CascadeInputs, QuirksMode, SharedStyleContext, StyleContext};
 use style::context::ThreadLocalStyleContext;
 use style::counter_style;
@@ -51,6 +52,8 @@ use style::gecko_bindings::bindings::{RawServoStyleSetBorrowed, RawServoStyleSet
 use style::gecko_bindings::bindings::{RawServoStyleSheetContentsBorrowed, ServoComputedDataBorrowed};
 use style::gecko_bindings::bindings::{RawServoStyleSheetContentsStrong, ServoStyleContextBorrowed};
 use style::gecko_bindings::bindings::{RawServoSupportsRule, RawServoSupportsRuleBorrowed};
+use style::gecko_bindings::bindings::{RawServoAuthorStyles, RawServoAuthorStylesBorrowed};
+use style::gecko_bindings::bindings::{RawServoAuthorStylesBorrowedMut, RawServoAuthorStylesOwned};
 use style::gecko_bindings::bindings::{ServoCssRulesBorrowed, ServoCssRulesStrong};
 use style::gecko_bindings::bindings::{nsACString, nsAString, nsCSSPropertyIDSetBorrowedMut};
 use style::gecko_bindings::bindings::Gecko_AddPropertyToSet;
@@ -1120,10 +1123,71 @@ pub extern "C" fn Servo_StyleSet_AppendStyleSheet(
     data.stylist.append_stylesheet(sheet, &guard);
 }
 
+#[no_mangle]
+pub extern "C" fn Servo_AuthorStyles_Create() -> *mut RawServoAuthorStyles {
+    Box::into_raw(Box::new(AuthorStyles::<GeckoStyleSheet>::new())) as *mut _
+}
+
+#[no_mangle]
+pub extern "C" fn Servo_AuthorStyles_Drop(
+    styles: RawServoAuthorStylesOwned,
+) {
+    let _ = styles.into_box::<AuthorStyles<_>>();
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn Servo_AuthorStyles_AppendStyleSheet(
+    styles: RawServoAuthorStylesBorrowedMut,
+    sheet: *const ServoStyleSheet,
+) {
+    let styles = AuthorStyles::<GeckoStyleSheet>::from_ffi_mut(styles);
+
+    let global_style_data = &*GLOBAL_STYLE_DATA;
+    let guard = global_style_data.shared_lock.read();
+    let sheet = GeckoStyleSheet::new(sheet);
+    styles.stylesheets.append_stylesheet(None, sheet, &guard);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn Servo_AuthorStyles_ForceDirty(
+    styles: RawServoAuthorStylesBorrowedMut,
+) {
+    let styles = AuthorStyles::<GeckoStyleSheet>::from_ffi_mut(styles);
+    styles.stylesheets.force_dirty();
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn Servo_AuthorStyles_Flush(
+    styles: RawServoAuthorStylesBorrowedMut,
+    document_set: RawServoStyleSetBorrowed,
+) {
+    let styles = AuthorStyles::<GeckoStyleSheet>::from_ffi_mut(styles);
+    // Try to avoid the atomic borrow below if possible.
+    if !styles.stylesheets.dirty() {
+        return;
+    }
+
+    let global_style_data = &*GLOBAL_STYLE_DATA;
+    let guard = global_style_data.shared_lock.read();
+
+    let document_data =
+        PerDocumentStyleData::from_ffi(document_set).borrow();
+
+    let stylist = &document_data.stylist;
+
+    // TODO(emilio): This is going to need an element or something to do proper
+    // invalidation in Shadow roots.
+    styles.flush::<GeckoElement>(
+        stylist.device(),
+        stylist.quirks_mode(),
+        &guard,
+    );
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn Servo_StyleSet_MediumFeaturesChanged(
     document_set: RawServoStyleSetBorrowed,
-    non_document_sets: *const nsTArray<*mut structs::ServoStyleSet>,
+    non_document_styles: *mut nsTArray<RawServoAuthorStylesBorrowedMut>,
     may_affect_default_style: bool,
 ) -> structs::MediumFeaturesChangedResult {
     let global_style_data = &*GLOBAL_STYLE_DATA;
@@ -1156,27 +1220,20 @@ pub unsafe extern "C" fn Servo_StyleSet_MediumFeaturesChanged(
     }
 
     let mut affects_non_document_rules = false;
-    for non_document_style_set in &**non_document_sets {
-        let non_document_data = &*(**non_document_style_set).mRawSet.mPtr;
-        let non_document_data =
-            mem::transmute::<&structs::RawServoStyleSet, &bindings::RawServoStyleSet>(non_document_data);
-        let mut non_document_data =
-            PerDocumentStyleData::from_ffi(non_document_data).borrow_mut();
-
-        let origins_changed =
-            non_document_data.stylist.media_features_change_changed_style(
-                &guards,
+    for author_styles in &mut **non_document_styles {
+        let author_styles =
+            AuthorStyles::<GeckoStyleSheet>::from_ffi_mut(&mut *author_styles);
+        let affected_style = author_styles.stylesheets.iter().any(|sheet| {
+            !author_styles.data.media_feature_affected_matches(
+                sheet,
+                &guards.author,
                 document_data.stylist.device(),
-            );
-        if !origins_changed.is_empty() {
+                document_data.stylist.quirks_mode(),
+            )
+        });
+        if affected_style {
             affects_non_document_rules = true;
-            // XBL stylesets are rebuilt entirely, so we need to mark them
-            // dirty from here instead of going through the stylist
-            // force_origin_dirty stuff, which would be useless.
-            //
-            // FIXME(emilio, bug 1436059): This is super-hacky, make XBL /
-            // Shadow DOM not use a style set at all.
-            (**non_document_style_set).mStylistState = structs::StylistState_StyleSheetsDirty;
+            author_styles.stylesheets.force_dirty();
         }
     }
 
@@ -4930,19 +4987,25 @@ pub extern "C" fn Servo_ParseCounterStyleName(
 #[no_mangle]
 pub unsafe extern "C" fn Servo_InvalidateStyleForDocStateChanges(
     root: RawGeckoElementBorrowed,
-    raw_style_sets: *const nsTArray<RawServoStyleSetBorrowed>,
+    document_style: RawServoStyleSetBorrowed,
+    non_document_styles: *const nsTArray<RawServoAuthorStylesBorrowed>,
     states_changed: u64,
 ) {
     use style::invalidation::element::document_state::DocumentStateInvalidationProcessor;
     use style::invalidation::element::invalidator::TreeStyleInvalidator;
 
-    let mut borrows = SmallVec::<[_; 20]>::with_capacity((*raw_style_sets).len());
-    for style_set in &**raw_style_sets {
-        borrows.push(PerDocumentStyleData::from_ffi(*style_set).borrow());
-    }
+    let document_data = PerDocumentStyleData::from_ffi(document_style).borrow();
+
+    let iter =
+        document_data.stylist.iter_origins().map(|(data, _origin)| data)
+        .chain((*non_document_styles).iter().map(|author_styles| {
+            let styles: &_ = AuthorStyles::<GeckoStyleSheet>::from_ffi(author_styles);
+            &styles.data
+        }));
+
     let root = GeckoElement(root);
     let mut processor = DocumentStateInvalidationProcessor::new(
-        borrows.iter().flat_map(|b| b.stylist.iter_origins().map(|(data, _origin)| data)),
+        iter,
         DocumentState::from_bits_truncate(states_changed),
         root.as_node().owner_doc().quirks_mode(),
     );