stylo: Centralize stylesheet handling.

This is needed for both bug 1357461 and bug 1273303, where I plan to add smarter
invalidations than what we have now.

Also, it's cleaner.

Ideally I'll move this onto stylist, though that may require extra work to make
it work fine for Servo, so for now let's just do the obvious thing.

components/style/gecko/data.rs

@@ -17,7 +17,8 @@ use shared_lock::{Locked, StylesheetGuards, SharedRwLockReadGuard};
 use std::collections::HashMap;
 use std::sync::Arc;
 use std::sync::mpsc::{Receiver, Sender, channel};
-use stylesheets::{FontFaceRule, Origin, Stylesheet};
+use stylesheet_set::StylesheetSet;
+use stylesheets::{FontFaceRule, Origin};
 use stylist::{ExtraStyleData, Stylist};
 
 /// The container for data that a Servo-backed Gecko document needs to style
@@ -27,13 +28,7 @@ pub struct PerDocumentStyleDataImpl {
     pub stylist: Arc<Stylist>,
 
     /// List of stylesheets, mirrored from Gecko.
-    pub stylesheets: Vec<Arc<Stylesheet>>,
-
-    /// Whether the stylesheets list above has changed since the last restyle.
-    pub stylesheets_changed: bool,
-
-    /// Has author style been disabled?
-    pub author_style_disabled: bool,
+    pub stylesheets: StylesheetSet,
 
     // FIXME(bholley): Hook these up to something.
     /// Unused. Will go away when we actually implement transitions and
@@ -66,9 +61,7 @@ impl PerDocumentStyleData {
 
         PerDocumentStyleData(AtomicRefCell::new(PerDocumentStyleDataImpl {
             stylist: Arc::new(Stylist::new(device)),
-            stylesheets: vec![],
-            stylesheets_changed: true,
-            author_style_disabled: false,
+            stylesheets: StylesheetSet::new(),
             new_animations_sender: new_anims_sender,
             new_animations_receiver: new_anims_receiver,
             running_animations: Arc::new(RwLock::new(HashMap::new())),
@@ -97,22 +90,25 @@ impl PerDocumentStyleDataImpl {
             let mut stylist = Arc::get_mut(&mut self.stylist).unwrap();
             Arc::get_mut(&mut stylist.device).unwrap().reset();
         }
-        self.stylesheets_changed = true;
+        self.stylesheets.force_dirty();
         self.flush_stylesheets(guard);
     }
 
     /// Recreate the style data if the stylesheets have changed.
     pub fn flush_stylesheets(&mut self, guard: &SharedRwLockReadGuard) {
-        if self.stylesheets_changed {
-            let mut stylist = Arc::get_mut(&mut self.stylist).unwrap();
-            let mut extra_data = ExtraStyleData {
-                font_faces: &mut self.font_faces,
-                author_style_disabled: Some(self.author_style_disabled),
-            };
-            stylist.update(&self.stylesheets, &StylesheetGuards::same(guard),
-                           None, true, &mut extra_data);
-            self.stylesheets_changed = false;
+        if !self.stylesheets.has_changed() {
+            return;
         }
+
+        let mut stylist = Arc::get_mut(&mut self.stylist).unwrap();
+        let mut extra_data = ExtraStyleData {
+            font_faces: &mut self.font_faces,
+            author_style_disabled: Some(self.stylesheets.author_style_disabled()),
+        };
+
+        stylist.update(&self.stylesheets.flush(),
+                       &StylesheetGuards::same(guard),
+                       None, true, &mut extra_data);
     }
 
     /// Get the default computed values for this document.

components/style/lib.rs

@@ -116,6 +116,7 @@ pub mod stylist;
 pub mod sequential;
 pub mod sink;
 pub mod str;
+pub mod stylesheet_set;
 pub mod stylesheets;
 pub mod supports;
 pub mod thread_state;

components/style/stylesheet_set.rs

@@ -0,0 +1,105 @@
+/* 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 centralized set of stylesheets for a document.
+
+use arc_ptr_eq;
+use std::sync::Arc;
+use stylesheets::Stylesheet;
+
+/// The set of stylesheets effective for a given document.
+pub struct StylesheetSet {
+    /// The actual list of all the stylesheets that apply to the given document.
+    ///
+    /// This is only a list of top-level stylesheets, and as such it doesn't
+    /// include recursive `@import` rules.
+    stylesheets: Vec<Arc<Stylesheet>>,
+
+    /// Whether the stylesheets list above has changed since the last restyle.
+    dirty: bool,
+
+    /// Has author style been disabled?
+    author_style_disabled: bool,
+}
+
+impl StylesheetSet {
+    /// Create a new empty StylesheetSet.
+    pub fn new() -> Self {
+        StylesheetSet {
+            stylesheets: vec![],
+            dirty: false,
+            author_style_disabled: false,
+        }
+    }
+
+    /// Returns whether author styles have been disabled for the current
+    /// stylesheet set.
+    pub fn author_style_disabled(&self) -> bool {
+        self.author_style_disabled
+    }
+
+    fn remove_stylesheet_if_present(&mut self, sheet: &Arc<Stylesheet>) {
+        self.stylesheets.retain(|x| !arc_ptr_eq(x, sheet));
+    }
+
+    /// Appends a new stylesheet to the current set.
+    pub fn append_stylesheet(&mut self, sheet: &Arc<Stylesheet>) {
+        self.remove_stylesheet_if_present(sheet);
+        self.stylesheets.push(sheet.clone());
+        self.dirty = true;
+    }
+
+    /// Prepend a new stylesheet to the current set.
+    pub fn prepend_stylesheet(&mut self, sheet: &Arc<Stylesheet>) {
+        self.remove_stylesheet_if_present(sheet);
+        self.stylesheets.insert(0, sheet.clone());
+        self.dirty = true;
+    }
+
+    /// Insert a given stylesheet before another stylesheet in the document.
+    pub fn insert_stylesheet_before(&mut self,
+                                    sheet: &Arc<Stylesheet>,
+                                    before: &Arc<Stylesheet>) {
+        self.remove_stylesheet_if_present(sheet);
+        let index = self.stylesheets.iter().position(|x| {
+            arc_ptr_eq(x, before)
+        }).expect("`before` stylesheet not found");
+        self.stylesheets.insert(index, sheet.clone());
+        self.dirty = true;
+    }
+
+    /// Remove a given stylesheet from the set.
+    pub fn remove_stylesheet(&mut self, sheet: &Arc<Stylesheet>) {
+        self.remove_stylesheet_if_present(sheet);
+        self.dirty = true;
+    }
+
+    /// Notes that the author style has been disabled for this document.
+    pub fn set_author_style_disabled(&mut self, disabled: bool) {
+        if self.author_style_disabled == disabled {
+            return;
+        }
+        self.author_style_disabled = disabled;
+        self.dirty = true;
+    }
+
+    /// Returns whether the given set has changed from the last flush.
+    pub fn has_changed(&self) -> bool {
+        self.dirty
+    }
+
+    /// Flush the current set, unmarking it as dirty.
+    pub fn flush(&mut self) -> &[Arc<Stylesheet>] {
+        self.dirty = false;
+        &self.stylesheets
+    }
+
+    /// Mark the stylesheets as dirty, because something external may have
+    /// invalidated it.
+    ///
+    /// FIXME(emilio): Make this more granular.
+    pub fn force_dirty(&mut self) {
+        self.dirty = true;
+    }
+}

ports/geckolib/glue.rs

@@ -13,7 +13,6 @@ use std::env;
 use std::fmt::Write;
 use std::ptr;
 use std::sync::{Arc, Mutex};
-use style::arc_ptr_eq;
 use style::context::{QuirksMode, SharedStyleContext, StyleContext};
 use style::context::{ThreadLocalStyleContext, ThreadLocalStyleContextCreationInfo};
 use style::data::{ElementData, ElementStyles, RestyleData};
@@ -578,9 +577,7 @@ pub extern "C" fn Servo_StyleSet_AppendStyleSheet(raw_data: RawServoStyleSetBorr
     let guard = global_style_data.shared_lock.read();
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let sheet = HasArcFFI::as_arc(&raw_sheet);
-    data.stylesheets.retain(|x| !arc_ptr_eq(x, sheet));
-    data.stylesheets.push(sheet.clone());
-    data.stylesheets_changed = true;
+    data.stylesheets.append_stylesheet(sheet);
     if flush {
         data.flush_stylesheets(&guard);
     }
@@ -594,9 +591,7 @@ pub extern "C" fn Servo_StyleSet_PrependStyleSheet(raw_data: RawServoStyleSetBor
     let guard = global_style_data.shared_lock.read();
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let sheet = HasArcFFI::as_arc(&raw_sheet);
-    data.stylesheets.retain(|x| !arc_ptr_eq(x, sheet));
-    data.stylesheets.insert(0, sheet.clone());
-    data.stylesheets_changed = true;
+    data.stylesheets.prepend_stylesheet(sheet);
     if flush {
         data.flush_stylesheets(&guard);
     }
@@ -612,10 +607,7 @@ pub extern "C" fn Servo_StyleSet_InsertStyleSheetBefore(raw_data: RawServoStyleS
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let sheet = HasArcFFI::as_arc(&raw_sheet);
     let reference = HasArcFFI::as_arc(&raw_reference);
-    data.stylesheets.retain(|x| !arc_ptr_eq(x, sheet));
-    let index = data.stylesheets.iter().position(|x| arc_ptr_eq(x, reference)).unwrap();
-    data.stylesheets.insert(index, sheet.clone());
-    data.stylesheets_changed = true;
+    data.stylesheets.insert_stylesheet_before(sheet, reference);
     if flush {
         data.flush_stylesheets(&guard);
     }
@@ -629,8 +621,7 @@ pub extern "C" fn Servo_StyleSet_RemoveStyleSheet(raw_data: RawServoStyleSetBorr
     let guard = global_style_data.shared_lock.read();
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let sheet = HasArcFFI::as_arc(&raw_sheet);
-    data.stylesheets.retain(|x| !arc_ptr_eq(x, sheet));
-    data.stylesheets_changed = true;
+    data.stylesheets.remove_stylesheet(sheet);
     if flush {
         data.flush_stylesheets(&guard);
     }
@@ -648,8 +639,8 @@ pub extern "C" fn Servo_StyleSet_FlushStyleSheets(raw_data: RawServoStyleSetBorr
 pub extern "C" fn Servo_StyleSet_NoteStyleSheetsChanged(raw_data: RawServoStyleSetBorrowed,
                                                         author_style_disabled: bool) {
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
-    data.stylesheets_changed = true;
-    data.author_style_disabled = author_style_disabled;
+    data.stylesheets.force_dirty();
+    data.stylesheets.set_author_style_disabled(author_style_disabled);
 }
 
 #[no_mangle]