style: Parameterize the update and rebuild methods to take an iterator.

In preparation to avoid cloning the stylesheets while rebuilding in Gecko.

components/layout_thread/lib.rs

@@ -1091,7 +1091,7 @@ impl LayoutThread {
             marker: PhantomData,
         };
         let needs_dirtying = self.stylist.update(
-            &data.document_stylesheets,
+            data.document_stylesheets.iter(),
             &guards,
             Some(ua_stylesheets),
             data.stylesheets_changed,

components/style/gecko/data.rs

@@ -105,7 +105,7 @@ impl PerDocumentStyleDataImpl {
         let mut stylesheets = Vec::<Arc<Stylesheet>>::new();
         self.stylesheets.flush(&mut stylesheets);
         self.stylist.clear();
-        self.stylist.rebuild(stylesheets.as_slice(),
+        self.stylist.rebuild(stylesheets.iter(),
                              &StylesheetGuards::same(guard),
                              /* ua_sheets = */ None,
                              /* stylesheets_changed = */ true,

components/style/stylist.rs

@@ -268,13 +268,15 @@ impl Stylist {
     /// This method resets all the style data each time the stylesheets change
     /// (which is indicated by the `stylesheets_changed` parameter), or the
     /// device is dirty, which means we need to re-evaluate media queries.
-    pub fn rebuild<'a>(&mut self,
+    pub fn rebuild<'a, 'b, I>(&mut self,
-                       doc_stylesheets: &[Arc<Stylesheet>],
+                              doc_stylesheets: I,
                               guards: &StylesheetGuards,
                               ua_stylesheets: Option<&UserAgentStylesheets>,
                               stylesheets_changed: bool,
                               author_style_disabled: bool,
-                       extra_data: &mut ExtraStyleData<'a>) -> bool {
+                              extra_data: &mut ExtraStyleData<'a>) -> bool
+        where I: Iterator<Item = &'b Arc<Stylesheet>> + Clone,
+    {
         debug_assert!(!self.is_cleared || self.is_device_dirty);
 
         self.is_cleared = false;
@@ -287,7 +289,7 @@ impl Stylist {
 
         let cascaded_rule = ViewportRule {
             declarations: viewport::Cascade::from_stylesheets(
-                doc_stylesheets, guards.author, &self.device
+                doc_stylesheets.clone(), guards.author, &self.device
             ).finish(),
         };
 
@@ -317,7 +319,7 @@ impl Stylist {
         }
 
         // Only use author stylesheets if author styles are enabled.
-        let sheets_to_add = doc_stylesheets.iter().filter(|s| {
+        let sheets_to_add = doc_stylesheets.filter(|s| {
             !author_style_disabled || s.origin != Origin::Author
         });
 
@@ -338,13 +340,15 @@ impl Stylist {
 
     /// clear the stylist and then rebuild it.  Chances are, you want to use
     /// either clear() or rebuild(), with the latter done lazily, instead.
-    pub fn update<'a>(&mut self,
+    pub fn update<'a, 'b, I>(&mut self,
-                      doc_stylesheets: &[Arc<Stylesheet>],
+                             doc_stylesheets: I,
                              guards: &StylesheetGuards,
                              ua_stylesheets: Option<&UserAgentStylesheets>,
                              stylesheets_changed: bool,
                              author_style_disabled: bool,
-                      extra_data: &mut ExtraStyleData<'a>) -> bool {
+                             extra_data: &mut ExtraStyleData<'a>) -> bool
+        where I: Iterator<Item = &'b Arc<Stylesheet>> + Clone,
+    {
         debug_assert!(!self.is_cleared || self.is_device_dirty);
 
         // We have to do a dirtiness check before clearing, because if
@@ -357,7 +361,9 @@ impl Stylist {
                      author_style_disabled, extra_data)
     }
 
-    fn add_stylesheet<'a>(&mut self, stylesheet: &Stylesheet, guard: &SharedRwLockReadGuard,
+    fn add_stylesheet<'a>(&mut self,
+                          stylesheet: &Stylesheet,
+                          guard: &SharedRwLockReadGuard,
                           extra_data: &mut ExtraStyleData<'a>) {
         if stylesheet.disabled() || !stylesheet.is_effective_for_device(&self.device, guard) {
             return;
@@ -656,10 +662,12 @@ impl Stylist {
     /// FIXME(emilio): The semantics of the device for Servo and Gecko are
     /// different enough we may want to unify them.
     #[cfg(feature = "servo")]
-    pub fn set_device(&mut self, mut device: Device, guard: &SharedRwLockReadGuard,
+    pub fn set_device(&mut self,
+                      mut device: Device,
+                      guard: &SharedRwLockReadGuard,
                       stylesheets: &[Arc<Stylesheet>]) {
         let cascaded_rule = ViewportRule {
-            declarations: viewport::Cascade::from_stylesheets(stylesheets, guard, &device).finish(),
+            declarations: viewport::Cascade::from_stylesheets(stylesheets.iter(), guard, &device).finish(),
         };
 
         self.viewport_constraints =

components/style/viewport.rs

@@ -26,6 +26,7 @@ use std::iter::Enumerate;
 use std::str::Chars;
 use style_traits::{PinchZoomFactor, ToCss};
 use style_traits::viewport::{Orientation, UserZoom, ViewportConstraints, Zoom};
+use stylearc::Arc;
 use stylesheets::{Stylesheet, Origin};
 use values::computed::{Context, ToComputedValue};
 use values::specified::{NoCalcLength, LengthOrPercentageOrAuto, ViewportPercentageLength};
@@ -329,7 +330,6 @@ fn is_whitespace_separator_or_equals(c: &char) -> bool {
 }
 
 impl Parse for ViewportRule {
-    #[allow(missing_docs)]
     fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
         let parser = ViewportRuleParser { context: context };
 
@@ -545,14 +545,15 @@ impl Cascade {
         }
     }
 
-    pub fn from_stylesheets<'a, I>(stylesheets: I, guard: &SharedRwLockReadGuard,
+    pub fn from_stylesheets<'a, I>(stylesheets: I,
-                                   device: &Device) -> Self
+                                   guard: &SharedRwLockReadGuard,
-        where I: IntoIterator,
+                                   device: &Device)
-              I::Item: AsRef<Stylesheet>,
+                                   -> Self
+        where I: Iterator<Item = &'a Arc<Stylesheet>>,
     {
         let mut cascade = Self::new();
         for stylesheet in stylesheets {
-            stylesheet.as_ref().effective_viewport_rules(device, guard, |rule| {
+            stylesheet.effective_viewport_rules(device, guard, |rule| {
                 for declaration in &rule.declarations {
                     cascade.add(Cow::Borrowed(declaration))
                 }

tests/unit/style/viewport.rs

@@ -25,7 +25,7 @@ macro_rules! stylesheet {
         stylesheet!($css, $origin, $error_reporter, SharedRwLock::new())
     };
     ($css:expr, $origin:ident, $error_reporter:expr, $shared_lock:expr) => {
-        Box::new(Stylesheet::from_str(
+        Arc::new(Stylesheet::from_str(
             $css,
             ServoUrl::parse("http://localhost").unwrap(),
             Origin::$origin,
@@ -269,7 +269,7 @@ fn multiple_stylesheets_cascading() {
                     Author, error_reporter, shared_lock.clone())
     ];
 
-    let declarations = Cascade::from_stylesheets(&stylesheets, &shared_lock.read(), &device).finish();
+    let declarations = Cascade::from_stylesheets(stylesheets.iter(), &shared_lock.read(), &device).finish();
     assert_decl_len!(declarations == 3);
     assert_decl_eq!(&declarations[0], UserAgent, Zoom: Zoom::Number(1.));
     assert_decl_eq!(&declarations[1], User, MinHeight: viewport_length!(200., px));
@@ -283,7 +283,7 @@ fn multiple_stylesheets_cascading() {
         stylesheet!("@viewport { min-width: 300px !important; min-height: 300px !important; zoom: 3 !important; }",
                     Author, error_reporter, shared_lock.clone())
     ];
-    let declarations = Cascade::from_stylesheets(&stylesheets, &shared_lock.read(), &device).finish();
+    let declarations = Cascade::from_stylesheets(stylesheets.iter(), &shared_lock.read(), &device).finish();
     assert_decl_len!(declarations == 3);
     assert_decl_eq!(&declarations[0], UserAgent, MinWidth: viewport_length!(100., px), !important);
     assert_decl_eq!(&declarations[1], User, MinHeight: viewport_length!(200., px), !important);