Implement Gecko's pseudo element matching

Signed-off-by: stevennovaryo <steven.novaryo@gmail.com>

components/layout/stylesheets/servo.css

@@ -19,26 +19,26 @@ textarea {
   font-size: 0.8333em;
 }
 
-::-servo-text-control-inner-editor {
+input::-servo-text-control-inner-editor {
   overflow-wrap: normal;
   pointer-events: auto;
 }
 
-::-servo-text-control-inner-container {
+input::-servo-text-control-inner-container {
   position: relative;
   height: 100%;
   pointer-events: none;
   display: flex;
 }
 
-::-servo-text-control-inner-editor, ::-servo-text-control-placeholder {
+input::-servo-text-control-inner-editor, input::-servo-text-control-placeholder {
   white-space: pre;
   margin-block: auto !important;
   inset-block: 0 !important;
   block-size: fit-content !important;
 }
 
-::-servo-text-control-placeholder {
+input::-servo-text-control-placeholder {
   overflow: hidden !important;
   position: absolute !important;
   color: grey !important;

components/script/dom/element.rs

@@ -666,6 +666,10 @@ impl Element {
             .upcast::<Node>()
             .set_containing_shadow_root(Some(&shadow_root));
 
+        if is_ua_widget == IsUserAgentWidget::Yes {
+            shadow_root.upcast::<Node>().set_in_ua_widget();
+        }
+
         let bind_context = BindContext {
             tree_connected: self.upcast::<Node>().is_connected(),
             tree_is_in_a_document_tree: self.upcast::<Node>().is_in_a_document_tree(),

components/script/dom/node.rs

@@ -231,9 +231,12 @@ bitflags! {
         /// needs extra work or not
         const HAS_WEIRD_PARSER_INSERTION_MODE = 1 << 11;
 
+        /// Whether this node reside in UA shadow DOM.
+        const IS_IN_UA_WIDGET = 1 << 12;
+
         /// Whether this node serves as the text container for editable content of
         /// <input> or <textarea> element.
-        const IS_TEXT_CONTROL_INNER_EDITOR = 1 << 12;
+        const IS_TEXT_CONTROL_INNER_EDITOR = 1 << 13;
     }
 }
 
@@ -292,6 +295,7 @@ impl Node {
         let parent_is_in_a_document_tree = self.is_in_a_document_tree();
         let parent_in_shadow_tree = self.is_in_a_shadow_tree();
         let parent_is_connected = self.is_connected();
+        let parent_is_in_ua_widget = self.in_ua_widget();
 
         for node in new_child.traverse_preorder(ShadowIncluding::No) {
             if parent_in_shadow_tree {
@@ -306,6 +310,7 @@ impl Node {
             );
             node.set_flag(NodeFlags::IS_IN_SHADOW_TREE, parent_in_shadow_tree);
             node.set_flag(NodeFlags::IS_CONNECTED, parent_is_connected);
+            node.set_flag(NodeFlags::IS_IN_UA_WIDGET, parent_is_in_ua_widget);
 
             // Out-of-document elements never have the descendants flag set.
             debug_assert!(!node.get_flag(NodeFlags::HAS_DIRTY_DESCENDANTS));
@@ -711,6 +716,14 @@ impl Node {
             .contains(NodeFlags::IS_TEXT_CONTROL_INNER_EDITOR)
     }
 
+    pub(crate) fn set_in_ua_widget(&self) {
+        self.set_flag(NodeFlags::IS_IN_UA_WIDGET, true)
+    }
+
+    pub(crate) fn in_ua_widget(&self) -> bool {
+        self.flags.get().contains(NodeFlags::IS_IN_UA_WIDGET)
+    }
+
     /// Returns the type ID of this node.
     pub(crate) fn type_id(&self) -> NodeTypeId {
         match *self.eventtarget.type_id() {
@@ -1664,6 +1677,7 @@ pub(crate) trait LayoutNodeHelpers<'dom> {
     fn iframe_pipeline_id(self) -> Option<PipelineId>;
     fn opaque(self) -> OpaqueNode;
     fn pseudo_element(&self) -> Option<PseudoElement>;
+    fn in_ua_widget(&self) -> bool;
 }
 
 impl<'dom> LayoutDom<'dom, Node> {
@@ -1937,13 +1951,16 @@ impl<'dom> LayoutNodeHelpers<'dom> for LayoutDom<'dom, Node> {
         unsafe { OpaqueNode(self.get_jsobject() as usize) }
     }
 
-    #[allow(unsafe_code)]
     fn pseudo_element(&self) -> Option<PseudoElement> {
         self.unsafe_get()
             .rare_data()
             .as_ref()
             .and_then(|data| data.pseudo_element)
     }
+
+    fn in_ua_widget(&self) -> bool {
+        self.unsafe_get().in_ua_widget()
+    }
 }
 
 //

components/script/dom/shadowroot.rs

@@ -47,7 +47,7 @@ use crate::script_runtime::CanGc;
 use crate::stylesheet_set::StylesheetSetRef;
 
 /// Whether a shadow root hosts an User Agent widget.
-#[derive(JSTraceable, MallocSizeOf, PartialEq)]
+#[derive(JSTraceable, MallocSizeOf, PartialEq, Clone, Copy)]
 pub(crate) enum IsUserAgentWidget {
     No,
     Yes,

components/script/layout_dom/element.rs

@@ -327,6 +327,16 @@ impl<'dom> style::dom::TElement for ServoLayoutElement<'dom> {
             .set_flag(NodeFlags::HAS_DIRTY_DESCENDANTS, false)
     }
 
+    #[inline]
+    fn matches_user_and_content_rules(&self) -> bool {
+        !self.as_node().node.in_ua_widget()
+    }
+
+    #[inline]
+    fn implemented_pseudo_element(&self) -> Option<PseudoElement> {
+        self.as_node().node.pseudo_element()
+    }
+
     fn store_children_to_process(&self, n: isize) {
         let data = self.get_style_data().unwrap();
         data.parallel
@@ -631,16 +641,27 @@ impl<'dom> ::selectors::Element for ServoLayoutElement<'dom> {
             self.element.namespace() == other.element.namespace()
     }
 
+    #[inline]
     fn is_pseudo_element(&self) -> bool {
-        false
+        self.element.upcast::<Node>().pseudo_element().is_some()
+    }
+
+    #[inline]
+    fn pseudo_element_originating_element(&self) -> Option<Self> {
+        debug_assert!(self.is_pseudo_element());
+        if self.element.upcast::<Node>().in_ua_widget() {
+            self.containing_shadow_host()
+        } else {
+            self.parent_element()
+        }
     }
 
     fn match_pseudo_element(
         &self,
-        _pseudo: &PseudoElement,
+        pseudo: &PseudoElement,
         _context: &mut MatchingContext<Self::Impl>,
     ) -> bool {
-        false
+        self.element.upcast::<Node>().pseudo_element() == Some(*pseudo)
     }
 
     fn match_non_ts_pseudo_class(
@@ -893,8 +914,9 @@ impl ::selectors::Element for ServoThreadSafeLayoutElement<'_> {
         ::selectors::OpaqueElement::new(unsafe { &*(self.as_node().opaque().0 as *const ()) })
     }
 
+    #[inline]
     fn is_pseudo_element(&self) -> bool {
-        false
+        self.element.is_pseudo_element()
     }
 
     fn parent_element(&self) -> Option<Self> {
@@ -903,11 +925,13 @@ impl ::selectors::Element for ServoThreadSafeLayoutElement<'_> {
     }
 
     fn parent_node_is_shadow_root(&self) -> bool {
-        false
+        self.element.parent_node_is_shadow_root()
     }
 
     fn containing_shadow_host(&self) -> Option<Self> {
-        None
+        self.element
+            .containing_shadow_host()
+            .and_then(|element| element.as_node().to_threadsafe().as_element())
     }
 
     // Skips non-element nodes
@@ -952,12 +976,20 @@ impl ::selectors::Element for ServoThreadSafeLayoutElement<'_> {
             self.element.namespace() == other.element.namespace()
     }
 
+    #[inline]
+    fn pseudo_element_originating_element(&self) -> Option<Self> {
+        debug_assert!(self.is_pseudo_element());
+        self.element
+            .pseudo_element_originating_element()
+            .and_then(|element| element.as_node().to_threadsafe().as_element())
+    }
+
     fn match_pseudo_element(
         &self,
-        _pseudo: &PseudoElement,
+        pseudo: &PseudoElement,
         _context: &mut MatchingContext<Self::Impl>,
     ) -> bool {
-        false
+        self.element.implemented_pseudo_element() == Some(*pseudo)
     }
 
     fn attr_matches(

components/script/layout_dom/node.rs

@@ -244,10 +244,7 @@ pub struct ServoThreadSafeLayoutNode<'dom> {
 impl<'dom> ServoThreadSafeLayoutNode<'dom> {
     /// Creates a new `ServoThreadSafeLayoutNode` from the given `ServoLayoutNode`.
     pub fn new(node: ServoLayoutNode<'dom>) -> Self {
-        ServoThreadSafeLayoutNode {
-            node,
-            pseudo: node.node.pseudo_element(),
-        }
+        ServoThreadSafeLayoutNode { node, pseudo: None }
     }
 
     /// Returns the interior of this node as a `LayoutDom`. This is highly unsafe for layout to
@@ -443,7 +440,6 @@ pub struct ServoThreadSafeLayoutNodeChildrenIterator<'dom> {
 }
 
 impl<'dom> ServoThreadSafeLayoutNodeChildrenIterator<'dom> {
-    // MYNOTES: This seems to be unused anywhere.
     pub fn new(parent: ServoThreadSafeLayoutNode<'dom>) -> Self {
         let first_child = match parent.pseudo_element() {
             None => parent