Auto merge of #18962 - upsuper:tree-pseudos, r=emilio

Support matching for ::-moz-tree-* pseudo-elements

This is the Servo side change of [bug 1397644](https://bugzilla.mozilla.org/show_bug.cgi?id=1397644).

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ports/geckolib/glue.rs

@@ -84,6 +84,7 @@ use style::gecko_bindings::structs::{RawServoStyleRule, ServoStyleContextStrong,
 use style::gecko_bindings::structs::{ServoStyleSheet, SheetParsingMode, nsAtom, nsCSSPropertyID};
 use style::gecko_bindings::structs::{nsCSSFontFaceRule, nsCSSCounterStyleRule};
 use style::gecko_bindings::structs::{nsRestyleHint, nsChangeHint, PropertyValuePair};
+use style::gecko_bindings::structs::AtomArray;
 use style::gecko_bindings::structs::IterationCompositeOperation;
 use style::gecko_bindings::structs::MallocSizeOf as GeckoMallocSizeOf;
 use style::gecko_bindings::structs::OriginFlags;
@@ -126,7 +127,7 @@ use style::rule_cache::RuleCacheConditions;
 use style::rule_tree::{CascadeLevel, StrongRuleNode, StyleSource};
 use style::selector_parser::{PseudoElementCascadeType, SelectorImpl};
 use style::shared_lock::{SharedRwLockReadGuard, StylesheetGuards, ToCssWithGuard, Locked};
-use style::string_cache::Atom;
+use style::string_cache::{Atom, WeakAtom};
 use style::style_adjuster::StyleAdjuster;
 use style::stylesheets::{CssRule, CssRules, CssRuleType, CssRulesHelpers, DocumentRule};
 use style::stylesheets::{FontFeatureValuesRule, ImportRule, KeyframesRule, MediaRule};
@@ -1911,6 +1912,7 @@ pub extern "C" fn Servo_ResolvePseudoStyle(element: RawGeckoElementBorrowed,
         inherited_style,
         &*doc_data,
         is_probe,
+        /* matching_func = */ None,
     );
 
     match style {
@@ -1922,6 +1924,66 @@ pub extern "C" fn Servo_ResolvePseudoStyle(element: RawGeckoElementBorrowed,
     }
 }
 
+fn debug_atom_array(atoms: &AtomArray) -> String {
+    let mut result = String::from("[");
+    for atom in atoms.iter() {
+        if atom.mRawPtr.is_null() {
+            result += "(null), ";
+        } else {
+            let atom = unsafe { WeakAtom::new(atom.mRawPtr) };
+            write!(result, "{}, ", atom).unwrap();
+        }
+    }
+    result.push(']');
+    result
+}
+
+#[no_mangle]
+pub extern "C" fn Servo_ComputedValues_ResolveXULTreePseudoStyle(
+    element: RawGeckoElementBorrowed,
+    pseudo_tag: *mut nsAtom,
+    inherited_style: ServoStyleContextBorrowed,
+    input_word: *const AtomArray,
+    raw_data: RawServoStyleSetBorrowed
+) -> ServoStyleContextStrong {
+    let element = GeckoElement(element);
+    let data = element.borrow_data()
+        .expect("Calling ResolveXULTreePseudoStyle on unstyled element?");
+
+    let pseudo = unsafe {
+        Atom::with(pseudo_tag, |atom| {
+            PseudoElement::from_tree_pseudo_atom(atom, Box::new([]))
+        }).expect("ResolveXULTreePseudoStyle with a non-tree pseudo?")
+    };
+    let input_word = unsafe { input_word.as_ref().unwrap() };
+
+    let doc_data = PerDocumentStyleData::from_ffi(raw_data).borrow();
+
+    debug!("ResolveXULTreePseudoStyle: {:?} {:?} {}",
+           element, pseudo, debug_atom_array(input_word));
+
+    let matching_fn = |pseudo: &PseudoElement| {
+        let args = pseudo.tree_pseudo_args().expect("Not a tree pseudo-element?");
+        args.iter().all(|atom| {
+            input_word.iter().any(|item| atom.as_ptr() == item.mRawPtr)
+        })
+    };
+
+    let global_style_data = &*GLOBAL_STYLE_DATA;
+    let guard = global_style_data.shared_lock.read();
+    get_pseudo_style(
+        &guard,
+        element,
+        &pseudo,
+        RuleInclusion::All,
+        &data.styles,
+        Some(inherited_style),
+        &*doc_data,
+        /* is_probe = */ false,
+        Some(&matching_fn),
+    ).unwrap().into()
+}
+
 #[no_mangle]
 pub extern "C" fn Servo_SetExplicitStyle(element: RawGeckoElementBorrowed,
                                          style: ServoStyleContextBorrowed)
@@ -1965,6 +2027,7 @@ fn get_pseudo_style(
     inherited_styles: Option<&ComputedValues>,
     doc_data: &PerDocumentStyleDataImpl,
     is_probe: bool,
+    matching_func: Option<&Fn(&PseudoElement) -> bool>,
 ) -> Option<Arc<ComputedValues>> {
     let style = match pseudo.cascade_type() {
         PseudoElementCascadeType::Eager => {
@@ -2038,6 +2101,7 @@ fn get_pseudo_style(
                     base,
                     is_probe,
                     &metrics,
+                    matching_func,
                 )
         },
     };
@@ -3269,6 +3333,7 @@ pub extern "C" fn Servo_ResolveStyleLazily(
                     /* inherited_styles = */ None,
                     &*data,
                     is_probe,
+                    /* matching_func = */ None,
                 )
             }
             None => Some(styles.primary().clone()),