Bug 1792501: Part 3 - Let :has contribute to dependencies. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D185676

servo/components/selectors/parser.rs

@@ -1927,6 +1927,11 @@ impl<Impl: SelectorImpl> Component<Impl> {
                     return false;
                 }
             },
+            Has(ref list) => {
+                if !visitor.visit_relative_selector_list(list) {
+                    return false;
+                }
+            },
             _ => {},
         }
 

servo/components/selectors/visitor.rs

@@ -7,7 +7,7 @@
 #![deny(missing_docs)]
 
 use crate::attr::NamespaceConstraint;
-use crate::parser::{Combinator, Component, Selector, SelectorImpl};
+use crate::parser::{Combinator, Component, RelativeSelector, Selector, SelectorImpl};
 
 /// A trait to visit selector properties.
 ///
@@ -34,6 +34,14 @@ pub trait SelectorVisitor: Sized {
         true
     }
 
+    /// Visit a nested relative selector list. The caller is responsible to call visit
+    /// into the internal selectors if / as needed.
+    ///
+    /// The default implementation skips it altogether.
+    fn visit_relative_selector_list(&mut self, _list: &[RelativeSelector<Self::Impl>]) -> bool {
+        true
+    }
+
     /// Visit a nested selector list. The caller is responsible to call visit
     /// into the internal selectors if / as needed.
     ///
@@ -73,6 +81,8 @@ bitflags! {
         /// The visitor is inside :nth-child(.. of <selector list>) or
         /// :nth-last-child(.. of <selector list>)
         const NTH_OF = 1 << 3;
+        /// The visitor is inside :has(..)
+        const HAS = 1 << 4;
     }
 }
 
@@ -108,4 +118,19 @@ impl SelectorListKind {
     pub fn in_nth_of(&self) -> bool {
         self.intersects(SelectorListKind::NTH_OF)
     }
+
+    /// Whether the visitor is inside :has(..)
+    pub fn in_has(&self) -> bool {
+        self.intersects(SelectorListKind::HAS)
+    }
+
+    /// Whether this nested selector is relevant for nth-of dependencies.
+    pub fn relevant_to_nth_of_dependencies(&self) -> bool {
+        // Order of nesting for `:has` and `:nth-child(.. of ..)` doesn't matter, because:
+        // * `:has(:nth-child(.. of ..))`: The location of the anchoring element is
+        //   independent from where `:nth-child(.. of ..)` is applied.
+        // * `:nth-child(.. of :has(..))`: Invalidations inside `:has` must first use the
+        //   `:has` machinary to find the anchor, then carry out the remaining invalidation.
+        self.in_nth_of() && !self.in_has()
+    }
 }

servo/components/style/stylist.rs

@@ -2003,6 +2003,25 @@ fn component_needs_revalidation(
     }
 }
 
+impl<'a> StylistSelectorVisitor<'a> {
+    fn visit_nested_selector(
+        &mut self,
+        in_selector_list_of: SelectorListKind,
+        selector: &Selector<SelectorImpl>
+    ) {
+        let old_passed_rightmost_selector = self.passed_rightmost_selector;
+        let old_in_selector_list_of = self.in_selector_list_of;
+
+        self.passed_rightmost_selector = false;
+        self.in_selector_list_of = in_selector_list_of;
+        let _ret = selector.visit(self);
+        debug_assert!(_ret, "We never return false");
+
+        self.passed_rightmost_selector = old_passed_rightmost_selector;
+        self.in_selector_list_of = old_in_selector_list_of;
+    }
+}
+
 impl<'a> SelectorVisitor for StylistSelectorVisitor<'a> {
     type Impl = SelectorImpl;
 
@@ -2026,21 +2045,18 @@ impl<'a> SelectorVisitor for StylistSelectorVisitor<'a> {
     ) -> bool {
         let in_selector_list_of = self.in_selector_list_of | list_kind;
         for selector in list {
-            let mut nested = StylistSelectorVisitor {
-                passed_rightmost_selector: false,
-                needs_revalidation: &mut *self.needs_revalidation,
-                in_selector_list_of,
-                mapped_ids: &mut *self.mapped_ids,
-                nth_of_mapped_ids: &mut *self.nth_of_mapped_ids,
-                attribute_dependencies: &mut *self.attribute_dependencies,
-                nth_of_class_dependencies: &mut *self.nth_of_class_dependencies,
-                nth_of_attribute_dependencies: &mut *self.nth_of_attribute_dependencies,
-                state_dependencies: &mut *self.state_dependencies,
-                nth_of_state_dependencies: &mut *self.nth_of_state_dependencies,
-                document_state_dependencies: &mut *self.document_state_dependencies,
-            };
-            let _ret = selector.visit(&mut nested);
-            debug_assert!(_ret, "We never return false");
+            self.visit_nested_selector(in_selector_list_of, selector);
+        }
+        true
+    }
+
+    fn visit_relative_selector_list(
+        &mut self,
+        list: &[selectors::parser::RelativeSelector<Self::Impl>],
+    ) -> bool {
+        let in_selector_list_of = self.in_selector_list_of | SelectorListKind::HAS;
+        for selector in list {
+            self.visit_nested_selector(in_selector_list_of, &selector.selector);
         }
         true
     }
@@ -2051,7 +2067,7 @@ impl<'a> SelectorVisitor for StylistSelectorVisitor<'a> {
         name: &LocalName,
         lower_name: &LocalName,
     ) -> bool {
-        if self.in_selector_list_of.in_nth_of() {
+        if self.in_selector_list_of.relevant_to_nth_of_dependencies() {
             self.nth_of_attribute_dependencies.insert(name.clone());
             if name != lower_name {
                 self.nth_of_attribute_dependencies
@@ -2077,7 +2093,7 @@ impl<'a> SelectorVisitor for StylistSelectorVisitor<'a> {
                 self.document_state_dependencies
                     .insert(p.document_state_flag());
 
-                if self.in_selector_list_of.in_nth_of() {
+                if self.in_selector_list_of.relevant_to_nth_of_dependencies() {
                     self.nth_of_state_dependencies.insert(p.state_flag());
                 }
             },
@@ -2097,11 +2113,13 @@ impl<'a> SelectorVisitor for StylistSelectorVisitor<'a> {
                     self.mapped_ids.insert(id.0.clone());
                 }
 
-                if self.in_selector_list_of.in_nth_of() {
+                if self.in_selector_list_of.relevant_to_nth_of_dependencies() {
                     self.nth_of_mapped_ids.insert(id.0.clone());
                 }
             },
-            Component::Class(ref class) if self.in_selector_list_of.in_nth_of() => {
+            Component::Class(ref class)
+                if self.in_selector_list_of.relevant_to_nth_of_dependencies() =>
+            {
                 self.nth_of_class_dependencies.insert(class.0.clone());
             },
             _ => {},