Look for relevant links while matching

Adjust the matching process to look for a "relevant link" while matching.  A
"relevant link" is the element being matched if it is a link or the nearest
ancestor link.

Matching for links now depends on the `VisitedHandlingMode`, which determines
whether all links match as if they are unvisited (the default) or if the
relevant link matches as visited (and all others remain unvisited).

If a relevant link is ever found for any selector, track this as part of the
`MatchingContext` object.  This is used in the next patch to determine if an
additional match and cascade should be performed to compute the styles when
visited.

MozReview-Commit-ID: 3xUbRo7vpuD

1 files changed, 23 insertions, 11 deletions

diff --git a/components/script/layout_wrapper.rs b/components/script/layout_wrapper.rs
index 5241d01785d..eab6f2fd9c9 100644
--- a/components/script/layout_wrapper.rs
+++ b/components/script/layout_wrapper.rs
@@ -51,7 +51,7 @@ use script_layout_interface::{OpaqueStyleAndLayoutData, PartialPersistentLayoutD
 use script_layout_interface::wrapper_traits::{DangerousThreadSafeLayoutNode, GetLayoutData, LayoutNode};
 use script_layout_interface::wrapper_traits::{PseudoElementType, ThreadSafeLayoutElement, ThreadSafeLayoutNode};
 use selectors::attr::{AttrSelectorOperation, NamespaceConstraint};
-use selectors::matching::{ElementSelectorFlags, MatchingContext};
+use selectors::matching::{ElementSelectorFlags, MatchingContext, RelevantLinkStatus};
 use servo_atoms::Atom;
 use servo_url::ServoUrl;
 use std::fmt;
@@ -680,6 +680,7 @@ impl<'le> ::selectors::Element for ServoLayoutElement<'le> {
     fn match_non_ts_pseudo_class<F>(&self,
                                     pseudo_class: &NonTSPseudoClass,
                                     _: &mut MatchingContext,
+                                    _: &RelevantLinkStatus,
                                     _: &mut F)
                                     -> bool
         where F: FnMut(&Self, ElementSelectorFlags),
@@ -687,16 +688,7 @@ impl<'le> ::selectors::Element for ServoLayoutElement<'le> {
         match *pseudo_class {
             // https://github.com/servo/servo/issues/8718
             NonTSPseudoClass::Link |
-            NonTSPseudoClass::AnyLink => unsafe {
-                match self.as_node().script_type_id() {
-                    // https://html.spec.whatwg.org/multipage/#selector-link
-                    NodeTypeId::Element(ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLAnchorElement)) |
-                    NodeTypeId::Element(ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLAreaElement)) |
-                    NodeTypeId::Element(ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLLinkElement)) =>
-                        (*self.element.unsafe_get()).get_attr_val_for_layout(&ns!(), &local_name!("href")).is_some(),
-                    _ => false,
-                }
-            },
+            NonTSPseudoClass::AnyLink => self.is_link(),
             NonTSPseudoClass::Visited => false,
 
             // FIXME(#15746): This is wrong, we need to instead use extended filtering as per RFC4647
@@ -732,6 +724,20 @@ impl<'le> ::selectors::Element for ServoLayoutElement<'le> {
     }
 
     #[inline]
+    fn is_link(&self) -> bool {
+        unsafe {
+            match self.as_node().script_type_id() {
+                // https://html.spec.whatwg.org/multipage/#selector-link
+                NodeTypeId::Element(ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLAnchorElement)) |
+                NodeTypeId::Element(ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLAreaElement)) |
+                NodeTypeId::Element(ElementTypeId::HTMLElement(HTMLElementTypeId::HTMLLinkElement)) =>
+                    (*self.element.unsafe_get()).get_attr_val_for_layout(&ns!(), &local_name!("href")).is_some(),
+                _ => false,
+            }
+        }
+    }
+
+    #[inline]
     fn get_id(&self) -> Option<Atom> {
         unsafe {
             (*self.element.id_attribute()).clone()
@@ -1187,6 +1193,7 @@ impl<'le> ::selectors::Element for ServoThreadSafeLayoutElement<'le> {
     fn match_non_ts_pseudo_class<F>(&self,
                                     _: &NonTSPseudoClass,
                                     _: &mut MatchingContext,
+                                    _: &RelevantLinkStatus,
                                     _: &mut F)
                                     -> bool
         where F: FnMut(&Self, ElementSelectorFlags),
@@ -1196,6 +1203,11 @@ impl<'le> ::selectors::Element for ServoThreadSafeLayoutElement<'le> {
         false
     }
 
+    fn is_link(&self) -> bool {
+        warn!("ServoThreadSafeLayoutElement::is_link called");
+        false
+    }
+
     fn get_id(&self) -> Option<Atom> {
         debug!("ServoThreadSafeLayoutElement::get_id called");
         None