stylo: We have an Atom back-end now.

components/style/gecko_selector_impl.rs

@@ -26,6 +26,9 @@ pub struct GeckoSelectorImpl;
 ///
 /// This should allow us to avoid random FFI overhead when cloning/dropping
 /// pseudos.
+///
+/// Also, we can further optimize PartialEq and hash comparing/hashing only the
+/// atoms.
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub struct PseudoElement(Atom, bool);
 
@@ -41,8 +44,9 @@ impl PseudoElement {
     }
 
     #[inline]
-    fn from_atom_unchecked(atom: Atom, is_anon_box: bool) -> Self {
+    pub fn from_atom_unchecked(atom: Atom, is_anon_box: bool) -> Self {
         if cfg!(debug_assertions) {
+            // Do the check on debug regardless.
             match Self::from_atom(&*atom, true) {
                 Some(pseudo) => {
                     assert_eq!(pseudo.is_anon_box(), is_anon_box);

ports/geckolib/glue.rs

@@ -16,6 +16,7 @@ use gecko_bindings::ptr::{GeckoArcPrincipal, GeckoArcURI};
 use gecko_bindings::structs::ServoElementSnapshot;
 use gecko_bindings::structs::nsRestyleHint;
 use gecko_bindings::structs::{SheetParsingMode, nsIAtom};
+use gecko_string_cache::Atom;
 use snapshot::GeckoElementSnapshot;
 use std::mem::transmute;
 use std::ptr;
@@ -39,29 +40,6 @@ use traversal::RecalcStyleOnly;
 use url::Url;
 use wrapper::{DUMMY_BASE_URL, GeckoDocument, GeckoElement, GeckoNode, NonOpaqueStyleData};
 
-// TODO: This is ugly and should go away once we get an atom back-end.
-pub fn pseudo_element_from_atom(pseudo: *mut nsIAtom,
-                                in_ua_stylesheet: bool) -> Result<PseudoElement, String> {
-    use gecko_bindings::bindings::Gecko_GetAtomAsUTF16;
-    use selectors::parser::{ParserContext, SelectorImpl};
-
-    let pseudo_string = unsafe {
-        let mut length = 0;
-        let mut buff = Gecko_GetAtomAsUTF16(pseudo, &mut length);
-
-        // Handle the annoying preceding colon in front of everything in nsCSSAnonBoxList.h.
-        debug_assert!(length >= 2 && *buff == ':' as u16 && *buff.offset(1) != ':' as u16);
-        buff = buff.offset(1);
-        length -= 1;
-
-        String::from_utf16(slice::from_raw_parts(buff, length as usize)).unwrap()
-    };
-
-    let mut context = ParserContext::new();
-    context.in_user_agent_stylesheet = in_ua_stylesheet;
-    GeckoSelectorImpl::parse_pseudo_element(&context, &pseudo_string).map_err(|_| pseudo_string)
-}
-
 /*
  * For Gecko->Servo function calls, we need to redeclare the same signature that was declared in
  * the C header in Gecko. In order to catch accidental mismatches, we run rust-bindgen against
@@ -286,13 +264,8 @@ pub extern "C" fn Servo_GetComputedValuesForAnonymousBox(parent_style_or_null: *
     let data = PerDocumentStyleData::borrow_mut_from_raw(raw_data);
     data.flush_stylesheets();
 
-    let pseudo = match pseudo_element_from_atom(pseudo_tag, /* ua_stylesheet = */ true) {
-        Ok(pseudo) => pseudo,
-        Err(pseudo) => {
-            warn!("stylo: Unable to parse anonymous-box pseudo-element: {}", pseudo);
-            return ptr::null_mut();
-        }
-    };
+    let atom = unsafe { Atom::from_static(pseudo_tag) };
+    let pseudo = PseudoElement::from_atom_unchecked(atom, /* anon_box = */ true);
 
     type Helpers = ArcHelpers<ServoComputedValues, ComputedValues>;
 
@@ -320,14 +293,8 @@ pub extern "C" fn Servo_GetComputedValuesForPseudoElement(parent_style: *mut Ser
         }
     };
 
-    let pseudo = match pseudo_element_from_atom(pseudo_tag, /* ua_stylesheet = */ true) {
-        Ok(pseudo) => pseudo,
-        Err(pseudo) => {
-            warn!("stylo: Unable to parse anonymous-box pseudo-element: {}", pseudo);
-            return parent_or_null();
-        }
-    };
-
+    let atom = unsafe { Atom::from_static(pseudo_tag) };
+    let pseudo = PseudoElement::from_atom_unchecked(atom, /* anon_box = */ false);
 
     // The stylist consumes stylesheets lazily.
     let data = PerDocumentStyleData::borrow_mut_from_raw(raw_data);