script: Use atom comparison in more places, especially for attributes.

75% improvement in style recalc for Guardians of the Galaxy.

components/style/Cargo.toml

@@ -29,3 +29,11 @@ git = "https://github.com/servo/rust-cssparser"
 [dependencies.encoding]
 git = "https://github.com/lifthrasiir/rust-encoding"
 
+[dependencies.string_cache]
+git = "https://github.com/servo/string-cache"
+branch = "pre-rustup"
+
+[dependencies.string_cache_macros]
+git = "https://github.com/servo/string-cache"
+branch = "pre-rustup"
+

components/style/lib.rs

@@ -11,12 +11,14 @@
 
 #![feature(phase)]
 #[phase(plugin, link)] extern crate log;
+#[phase(plugin)] extern crate string_cache_macros;
 
 extern crate debug;
 extern crate collections;
 extern crate geom;
 extern crate num;
 extern crate serialize;
+extern crate string_cache;
 extern crate sync;
 extern crate url;
 

components/style/node.rs

@@ -9,7 +9,7 @@ use selectors::AttrSelector;
 use servo_util::atom::Atom;
 use servo_util::namespace::Namespace;
 
-
+// FIXME(pcwalton): When we get associated types in Rust, this can be nicer.
 pub trait TNode<E:TElement> : Clone {
     fn parent_node(&self) -> Option<Self>;
     /// Name is prefixed to avoid a conflict with TLayoutNode.
@@ -24,7 +24,7 @@ pub trait TNode<E:TElement> : Clone {
 }
 
 pub trait TElement {
-    fn get_attr(&self, namespace: &Namespace, attr: &str) -> Option<&'static str>;
+    fn get_attr(&self, namespace: &Namespace, attr: &Atom) -> Option<&'static str>;
     fn get_link(&self) -> Option<&'static str>;
     fn get_local_name<'a>(&'a self) -> &'a Atom;
     fn get_namespace<'a>(&'a self) -> &'a Namespace;
@@ -32,5 +32,13 @@ pub trait TElement {
     fn get_id(&self) -> Option<Atom>;
     fn get_disabled_state(&self) -> bool;
     fn get_enabled_state(&self) -> bool;
-    fn has_class(&self, name: &str) -> bool;
+    fn has_class(&self, name: &Atom) -> bool;
+
+    // Ordinarily I wouldn't use callbacks like this, but the alternative is
+    // really messy, since there is a `JSRef` and a `RefCell` involved. Maybe
+    // in the future when we have associated types and/or a more convenient
+    // JS GC story... --pcwalton
+    fn each_class(&self, callback: |&Atom|);
 }
+
+

components/style/selector_matching.rs

@@ -11,7 +11,6 @@ use url::Url;
 
 use servo_util::atom::Atom;
 use servo_util::bloom::BloomFilter;
-use servo_util::namespace;
 use servo_util::smallvec::VecLike;
 use servo_util::sort;
 
@@ -106,20 +105,14 @@ impl SelectorMap {
             None => {}
         }
 
-        match element.get_attr(&namespace::Null, "class") {
-            Some(ref class_attr) => {
-                // FIXME: Store classes pre-split as atoms to make the loop below faster.
-                for class in class_attr.split(SELECTOR_WHITESPACE) {
-                    SelectorMap::get_matching_rules_from_hash(node,
-                                                              parent_bf,
-                                                              &self.class_hash,
-                                                              &Atom::from_slice(class),
-                                                              matching_rules_list,
-                                                              shareable);
-                }
-            }
-            None => {}
-        }
+        element.each_class(|class| {
+            SelectorMap::get_matching_rules_from_hash(node,
+                                                      parent_bf,
+                                                      &self.class_hash,
+                                                      class,
+                                                      matching_rules_list,
+                                                      shareable);
+        });
 
         let local_name_hash = if node.is_html_element_in_html_document() {
             &self.lower_local_name_hash
@@ -467,7 +460,12 @@ impl DeclarationBlock {
     }
 }
 
-pub fn matches<E:TElement, N:TNode<E>>(selector_list: &SelectorList, element: &N, parent_bf: &Option<BloomFilter>) -> bool {
+pub fn matches<E:TElement,
+               N:TNode<E>>(
+               selector_list: &SelectorList,
+               element: &N,
+               parent_bf: &Option<BloomFilter>)
+               -> bool {
     get_selector_list_selectors(selector_list).iter().any(|selector|
         selector.pseudo_element.is_none() &&
         matches_compound_selector(&*selector.compound_selectors, element, parent_bf, &mut false))
@@ -544,11 +542,13 @@ enum SelectorMatchingResult {
 /// Quickly figures out whether or not the compound selector is worth doing more
 /// work on. If the simple selectors don't match, or there's a child selector
 /// that does not appear in the bloom parent bloom filter, we can exit early.
-fn can_fast_reject<E: TElement, N: TNode<E>>(
-  mut selector: &CompoundSelector,
-  element: &N,
-  parent_bf: &Option<BloomFilter>,
-  shareable: &mut bool) -> Option<SelectorMatchingResult> {
+fn can_fast_reject<E:TElement,
+                   N:TNode<E>>(
+                   mut selector: &CompoundSelector,
+                   element: &N,
+                   parent_bf: &Option<BloomFilter>,
+                   shareable: &mut bool)
+                   -> Option<SelectorMatchingResult> {
     if !selector.simple_selectors.iter().all(|simple_selector| {
       matches_simple_selector(simple_selector, element, shareable) }) {
         return Some(NotMatchedAndRestartFromClosestLaterSibling);
@@ -681,11 +681,11 @@ fn matches_compound_selector_internal<E:TElement,
 /// `main/css/matching.rs`.)
 #[inline]
 pub fn matches_simple_selector<E:TElement,
-                           N:TNode<E>>(
-                           selector: &SimpleSelector,
-                           element: &N,
-                           shareable: &mut bool)
-                           -> bool {
+                               N:TNode<E>>(
+                               selector: &SimpleSelector,
+                               element: &N,
+                               shareable: &mut bool)
+                               -> bool {
     match *selector {
         LocalNameSelector(LocalNameSelector { ref name, ref lower_name }) => {
             let name = if element.is_html_element_in_html_document() { lower_name } else { name };
@@ -710,7 +710,7 @@ pub fn matches_simple_selector<E:TElement,
         // TODO: cache and intern class names on elements.
         ClassSelector(ref class) => {
             let element = element.as_element();
-            element.has_class(class.as_slice())
+            element.has_class(class)
         }
 
         AttrExists(ref attr) => {
@@ -854,6 +854,7 @@ pub fn matches_simple_selector<E:TElement,
     }
 }
 
+#[inline]
 fn url_is_visited(_url: &str) -> bool {
     // FIXME: implement this.
     // This function will probably need to take a "session"
@@ -862,8 +863,7 @@ fn url_is_visited(_url: &str) -> bool {
 }
 
 #[inline]
-fn matches_generic_nth_child<'a,
-                             E:TElement,
+fn matches_generic_nth_child<E:TElement,
                              N:TNode<E>>(
                              element: &N,
                              a: i32,

components/style/selectors.rs

@@ -100,8 +100,8 @@ pub struct LocalNameSelector {
 
 #[deriving(Eq, PartialEq, Clone, Hash)]
 pub struct AttrSelector {
-    pub name: String,
-    pub lower_name: String,
+    pub name: Atom,
+    pub lower_name: Atom,
     pub namespace: NamespaceConstraint,
 }
 
@@ -442,8 +442,8 @@ fn parse_attribute_selector(content: Vec<ComponentValue>, namespaces: &Namespace
         Some((_, None)) => fail!("Implementation error, this should not happen."),
         Some((namespace, Some(local_name))) => AttrSelector {
             namespace: namespace,
-            lower_name: local_name.as_slice().to_ascii_lower(),
-            name: local_name,
+            lower_name: Atom::from_slice(local_name.as_slice().to_ascii_lower().as_slice()),
+            name: Atom::from_slice(local_name.as_slice()),
         },
     };
     skip_whitespace(iter);