auto merge of #3772 : pcwalton/servo/slim-down-fragment, r=metajack

16% performance improvement in layout (!)

r? @metajack (or whoever)

components/layout/construct.rs

@@ -238,12 +238,12 @@ impl<'a> FlowConstructor<'a> {
             Some(url) => {
                 // FIXME(pcwalton): The fact that image fragments store the cache within them makes
                 // little sense to me.
-                ImageFragment(ImageFragmentInfo::new(node,
-                                                     url,
-                                                     self.layout_context
-                                                         .shared
-                                                         .image_cache
-                                                         .clone()))
+                ImageFragment(box ImageFragmentInfo::new(node,
+                                                         url,
+                                                         self.layout_context
+                                                             .shared
+                                                             .image_cache
+                                                             .clone()))
             }
         }
     }
@@ -258,7 +258,7 @@ impl<'a> FlowConstructor<'a> {
                                                  -> SpecificFragmentInfo {
         match node.type_id() {
             Some(ElementNodeTypeId(HTMLIFrameElementTypeId)) => {
-                IframeFragment(IframeFragmentInfo::new(node))
+                IframeFragment(box IframeFragmentInfo::new(node))
             }
             Some(ElementNodeTypeId(HTMLImageElementTypeId)) => {
                 self.build_fragment_info_for_image(node, node.image_url())

components/layout/display_list_builder.rs

@@ -502,7 +502,7 @@ impl FragmentDisplayListBuilding for Fragment {
                 if opts::get().show_debug_fragment_borders {
                     self.build_debug_borders_around_text_fragments(display_list,
                                                                    flow_origin,
-                                                                   text_fragment,
+                                                                   &**text_fragment,
                                                                    clip_rect);
                 }
             }
@@ -559,7 +559,7 @@ impl FragmentDisplayListBuilding for Fragment {
         // the iframe is actually going to be displayed.
         match self.specific {
             IframeFragment(ref iframe_fragment) => {
-                self.finalize_position_and_size_of_iframe(iframe_fragment,
+                self.finalize_position_and_size_of_iframe(&**iframe_fragment,
                                                           absolute_fragment_bounds.origin,
                                                           layout_context)
             }

components/layout/incremental.rs

@@ -8,7 +8,7 @@ use style::ComputedValues;
 
 bitflags! {
     #[doc = "Individual layout actions that may be necessary after restyling."]
-    flags RestyleDamage: int {
+    flags RestyleDamage: u8 {
         #[doc = "Repaint the node itself."]
         #[doc = "Currently unused; need to decide how this propagates."]
         static Repaint = 0x01,

components/layout/inline.rs

@@ -391,7 +391,11 @@ impl LineBreaker {
     }
 
     fn try_append_to_line_by_new_line(&mut self, in_fragment: Fragment) -> bool {
-        if in_fragment.new_line_pos.len() == 0 {
+        let no_newline_positions = match in_fragment.newline_positions() {
+            None => true,
+            Some(ref positions) => positions.is_empty(),
+        };
+        if no_newline_positions {
             debug!("LineBreaker: Did not find a new-line character, so pushing the fragment to \
                    the line without splitting.");
             self.push_fragment_to_line(in_fragment);
@@ -406,28 +410,29 @@ impl LineBreaker {
         let writing_mode = self.floats.writing_mode;
 
         let split_fragment = |split: SplitInfo| {
-            let info =
-                ScannedTextFragmentInfo::new(
-                    run.clone(),
-                    split.range,
-                    in_fragment.border_box.size);
-            let size = LogicalSize::new(
-                writing_mode, split.inline_size, in_fragment.border_box.size.block);
+            let info = box ScannedTextFragmentInfo::new(run.clone(),
+                                                        split.range,
+                                                        (*in_fragment.newline_positions()
+                                                                     .unwrap()).clone(),
+                                                        in_fragment.border_box.size);
+            let size = LogicalSize::new(writing_mode,
+                                        split.inline_size,
+                                        in_fragment.border_box.size.block);
             in_fragment.transform(size, info)
         };
 
         debug!("LineBreaker: Pushing the fragment to the inline_start of the new-line character \
                 to the line.");
         let mut inline_start = split_fragment(inline_start);
         inline_start.save_new_line_pos();
-        inline_start.new_line_pos = vec![];
+        *inline_start.newline_positions_mut().unwrap() = vec![];
         self.push_fragment_to_line(inline_start);
 
         for inline_end in inline_end.into_iter() {
             debug!("LineBreaker: Deferring the fragment to the inline_end of the new-line \
                    character to the line.");
             let mut inline_end = split_fragment(inline_end);
-            inline_end.new_line_pos.remove(0);
+            inline_end.newline_positions_mut().unwrap().remove(0);
             self.work_list.push_front(inline_end);
         }
 
@@ -497,11 +502,10 @@ impl LineBreaker {
                                                                 line_is_empty);
         match split.map(|(inline_start, inline_end, run)| {
             let split_fragment = |split: SplitInfo| {
-                let info =
-                    ScannedTextFragmentInfo::new(
-                        run.clone(),
-                        split.range,
-                        in_fragment.border_box.size);
+                let info = box ScannedTextFragmentInfo::new(run.clone(),
+                                                            split.range,
+                                                            Vec::new(),
+                                                            in_fragment.border_box.size);
                 let size = LogicalSize::new(self.floats.writing_mode,
                                             split.inline_size,
                                             in_fragment.border_box.size.block);

components/layout/layout_debug.rs

@@ -92,8 +92,8 @@ impl Drop for Scope {
 /// Generate a unique ID. This is used for items such as Fragment
 /// which are often reallocated but represent essentially the
 /// same data.
-pub fn generate_unique_debug_id() -> uint {
-    unsafe { DEBUG_ID_COUNTER.fetch_add(1, SeqCst) }
+pub fn generate_unique_debug_id() -> u16 {
+    unsafe { DEBUG_ID_COUNTER.fetch_add(1, SeqCst) as u16 }
 }
 
 /// Begin a layout debug trace. If this has not been called,

components/layout/table_colgroup.rs

@@ -13,6 +13,7 @@ use layout_debug;
 use wrapper::ThreadSafeLayoutNode;
 
 use servo_util::geometry::Au;
+use std::cmp::max;
 use std::fmt;
 use style::computed_values::LengthOrPercentageOrAuto;
 
@@ -64,7 +65,7 @@ impl Flow for TableColGroupFlow {
             // Retrieve the specified value from the appropriate CSS property.
             let inline_size = fragment.style().content_inline_size();
             let span: int = match fragment.specific {
-                TableColumnFragment(col_fragment) => col_fragment.span.unwrap_or(1),
+                TableColumnFragment(col_fragment) => max(col_fragment.span, 1),
                 _ => fail!("non-table-column fragment inside table column?!"),
             };
             for _ in range(0, span) {

components/layout/text.rs

@@ -160,16 +160,17 @@ impl TextRunScanner {
             }
 
             let text_size = old_fragment.border_box.size;
+            let &NewLinePositions(ref mut new_line_positions) =
+                new_line_positions.get_mut(logical_offset);
             let new_text_fragment_info =
-                ScannedTextFragmentInfo::new(run.clone(), range, text_size);
+                box ScannedTextFragmentInfo::new(run.clone(),
+                                                 range,
+                                                 mem::replace(new_line_positions, Vec::new()),
+                                                 text_size);
             let new_metrics = new_text_fragment_info.run.metrics_for_range(&range);
             let bounding_box_size = bounding_box_for_run_metrics(&new_metrics,
                                                                  old_fragment.style.writing_mode);
-            let mut new_fragment = old_fragment.transform(bounding_box_size,
-                                                          new_text_fragment_info);
-            let &NewLinePositions(ref mut new_line_positions) =
-                new_line_positions.get_mut(logical_offset);
-            new_fragment.new_line_pos = mem::replace(new_line_positions, Vec::new());
+            let new_fragment = old_fragment.transform(bounding_box_size, new_text_fragment_info);
             out_fragments.push(new_fragment)
         }