Store selectors in Arc early to avoid some copying.

src/components/style/selector_matching.rs

@@ -281,8 +281,7 @@ impl Stylist {
                             Some(After) => &mut after_map,
                         };
                         map.$priority.insert(Rule {
-                                // TODO: avoid copying?
+                                selector: selector.compound_selectors.clone(),
-                                selector: Arc::new(selector.compound_selectors.clone()),
                                 specificity: selector.specificity,
                                 declarations: style_rule.declarations.$priority.clone(),
                                 source_order: self.rules_source_order,
@@ -735,7 +734,7 @@ mod tests {
             .unwrap().move_iter().map(|s| {
                 Rule {
                     specificity: s.specificity,
-                    selector: Arc::new(s.compound_selectors),
+                    selector: s.compound_selectors,
                     declarations: Arc::new(~[]),
                     source_order: i,
                 }

src/components/style/selectors.rs

@@ -4,14 +4,25 @@
 
 use std::{vec, iter};
 use std::ascii::StrAsciiExt;
+use extra::arc::Arc;
+
 use cssparser::ast::*;
 use cssparser::parse_nth;
+
 use namespaces::NamespaceMap;
 
 
+// Only used in tests
+impl Eq for Arc<CompoundSelector> {
+    fn eq(&self, other: &Arc<CompoundSelector>) -> bool {
+        self.get() == other.get()
+    }
+}
+
+
 #[deriving(Eq, Clone)]
 pub struct Selector {
-    compound_selectors: CompoundSelector,
+    compound_selectors: Arc<CompoundSelector>,
     pseudo_element: Option<PseudoElement>,
     specificity: u32,
 }
@@ -157,7 +168,7 @@ fn parse_selector(iter: &mut Iter, namespaces: &NamespaceMap)
     }
     Some(Selector {
         specificity: compute_specificity(&compound, &pseudo_element),
-        compound_selectors: compound,
+        compound_selectors: Arc::new(compound),
         pseudo_element: pseudo_element,
     })
 }
@@ -549,6 +560,7 @@ fn skip_whitespace(iter: &mut Iter) -> bool {
 
 #[cfg(test)]
 mod tests {
+    use extra::arc::Arc;
     use cssparser;
     use namespaces::NamespaceMap;
     use super::*;
@@ -567,48 +579,48 @@ mod tests {
     fn test_parsing() {
         assert_eq!(parse(""), None)
         assert_eq!(parse("e"), Some(~[Selector{
-            compound_selectors: CompoundSelector {
+            compound_selectors: Arc::new(CompoundSelector {
                 simple_selectors: ~[LocalNameSelector(~"e")],
                 next: None,
-            },
+            }),
             pseudo_element: None,
             specificity: specificity(0, 0, 1),
         }]))
         assert_eq!(parse(".foo"), Some(~[Selector{
-            compound_selectors: CompoundSelector {
+            compound_selectors: Arc::new(CompoundSelector {
                 simple_selectors: ~[ClassSelector(~"foo")],
                 next: None,
-            },
+            }),
             pseudo_element: None,
             specificity: specificity(0, 1, 0),
         }]))
         assert_eq!(parse("#bar"), Some(~[Selector{
-            compound_selectors: CompoundSelector {
+            compound_selectors: Arc::new(CompoundSelector {
                 simple_selectors: ~[IDSelector(~"bar")],
                 next: None,
-            },
+            }),
             pseudo_element: None,
             specificity: specificity(1, 0, 0),
         }]))
         assert_eq!(parse("e.foo#bar"), Some(~[Selector{
-            compound_selectors: CompoundSelector {
+            compound_selectors: Arc::new(CompoundSelector {
                 simple_selectors: ~[LocalNameSelector(~"e"),
                                     ClassSelector(~"foo"),
                                     IDSelector(~"bar")],
                 next: None,
-            },
+            }),
             pseudo_element: None,
             specificity: specificity(1, 1, 1),
         }]))
         assert_eq!(parse("e.foo #bar"), Some(~[Selector{
-            compound_selectors: CompoundSelector {
+            compound_selectors: Arc::new(CompoundSelector {
                 simple_selectors: ~[IDSelector(~"bar")],
                 next: Some((~CompoundSelector {
                     simple_selectors: ~[LocalNameSelector(~"e"),
                                         ClassSelector(~"foo")],
                     next: None,
                 }, Descendant)),
-            },
+            }),
             pseudo_element: None,
             specificity: specificity(1, 1, 1),
         }]))