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

components/style/gecko/wrapper.rs

@@ -65,7 +65,7 @@ use rule_tree::CascadeLevel as ServoCascadeLevel;
 use selector_parser::ElementExt;
 use selectors::Element;
 use selectors::attr::{AttrSelectorOperation, AttrSelectorOperator, CaseSensitivity, NamespaceConstraint};
-use selectors::matching::{ElementSelectorFlags, MatchingContext, MatchingMode};
+use selectors::matching::{ElementSelectorFlags, MatchingContext, MatchingMode, RelevantLinkStatus};
 use shared_lock::Locked;
 use sink::Push;
 use std::cell::RefCell;
@@ -1236,6 +1236,7 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
     fn match_non_ts_pseudo_class<F>(&self,
                                     pseudo_class: &NonTSPseudoClass,
                                     context: &mut MatchingContext,
+                                    relevant_link: &RelevantLinkStatus,
                                     flags_setter: &mut F)
                                     -> bool
         where F: FnMut(&Self, ElementSelectorFlags),
@@ -1243,8 +1244,6 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
         use selectors::matching::*;
         match *pseudo_class {
             NonTSPseudoClass::AnyLink |
-            NonTSPseudoClass::Link |
-            NonTSPseudoClass::Visited |
             NonTSPseudoClass::Active |
             NonTSPseudoClass::Focus |
             NonTSPseudoClass::Hover |
@@ -1293,6 +1292,8 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
                 // here, to handle `:any-link` correctly.
                 self.get_state().intersects(pseudo_class.state_flag())
             },
+            NonTSPseudoClass::Link => relevant_link.is_unvisited(self, context),
+            NonTSPseudoClass::Visited => relevant_link.is_visited(self, context),
             NonTSPseudoClass::MozFirstNode => {
                 flags_setter(self, HAS_EDGE_CHILD_SELECTOR);
                 let mut elem = self.as_node();
@@ -1369,6 +1370,15 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
         }
     }
 
+    #[inline]
+    fn is_link(&self) -> bool {
+        let mut context = MatchingContext::new(MatchingMode::Normal, None);
+        self.match_non_ts_pseudo_class(&NonTSPseudoClass::AnyLink,
+                                       &mut context,
+                                       &RelevantLinkStatus::default(),
+                                       &mut |_, _| {})
+    }
+
     fn get_id(&self) -> Option<Atom> {
         if !self.has_id() {
             return None;
@@ -1420,14 +1430,6 @@ impl<'a> NamespaceConstraintHelpers for NamespaceConstraint<&'a Namespace> {
 }
 
 impl<'le> ElementExt for GeckoElement<'le> {
-    #[inline]
-    fn is_link(&self) -> bool {
-        let mut context = MatchingContext::new(MatchingMode::Normal, None);
-        self.match_non_ts_pseudo_class(&NonTSPseudoClass::AnyLink,
-                                       &mut context,
-                                       &mut |_, _| {})
-    }
-
     #[inline]
     fn matches_user_and_author_rules(&self) -> bool {
         self.flags() & (NODE_IS_IN_NATIVE_ANONYMOUS_SUBTREE as u32) == 0

components/style/restyle_hints.rs

@@ -20,7 +20,7 @@ use selector_map::{SelectorMap, SelectorMapEntry};
 use selector_parser::{NonTSPseudoClass, PseudoElement, SelectorImpl, Snapshot, SnapshotMap, AttrValue};
 use selectors::Element;
 use selectors::attr::{AttrSelectorOperation, NamespaceConstraint};
-use selectors::matching::{ElementSelectorFlags, MatchingContext, MatchingMode};
+use selectors::matching::{ElementSelectorFlags, MatchingContext, MatchingMode, RelevantLinkStatus};
 use selectors::matching::matches_selector;
 use selectors::parser::{Combinator, Component, Selector, SelectorInner, SelectorMethods};
 use selectors::visitor::SelectorVisitor;
@@ -535,6 +535,7 @@ impl<'a, E> Element for ElementWrapper<'a, E>
     fn match_non_ts_pseudo_class<F>(&self,
                                     pseudo_class: &NonTSPseudoClass,
                                     context: &mut MatchingContext,
+                                    relevant_link: &RelevantLinkStatus,
                                     _setter: &mut F)
                                     -> bool
         where F: FnMut(&Self, ElementSelectorFlags),
@@ -580,6 +581,7 @@ impl<'a, E> Element for ElementWrapper<'a, E>
         if flag.is_empty() {
             return self.element.match_non_ts_pseudo_class(pseudo_class,
                                                           context,
+                                                          relevant_link,
                                                           &mut |_, _| {})
         }
         match self.snapshot().and_then(|s| s.state()) {
@@ -587,6 +589,7 @@ impl<'a, E> Element for ElementWrapper<'a, E>
             None => {
                 self.element.match_non_ts_pseudo_class(pseudo_class,
                                                        context,
+                                                       relevant_link,
                                                        &mut |_, _| {})
             }
         }
@@ -600,6 +603,14 @@ impl<'a, E> Element for ElementWrapper<'a, E>
         self.element.match_pseudo_element(pseudo_element, context)
     }
 
+    fn is_link(&self) -> bool {
+        let mut context = MatchingContext::new(MatchingMode::Normal, None);
+        self.match_non_ts_pseudo_class(&NonTSPseudoClass::AnyLink,
+                                       &mut context,
+                                       &RelevantLinkStatus::default(),
+                                       &mut |_, _| {})
+    }
+
     fn parent_element(&self) -> Option<Self> {
         self.element.parent_element()
             .map(|e| ElementWrapper::new(e, self.snapshot_map))

components/style/selector_parser.rs

@@ -103,9 +103,6 @@ pub enum PseudoElementCascadeType {
 
 /// An extension to rust-selector's `Element` trait.
 pub trait ElementExt: Element<Impl=SelectorImpl> + Debug {
-    /// Whether this element is a `link`.
-    fn is_link(&self) -> bool;
-
     /// Whether this element should match user and author rules.
     ///
     /// We use this for Native Anonymous Content in Gecko.

components/style/servo/selector_parser.rs

@@ -16,7 +16,6 @@ use restyle_hints::ElementSnapshot;
 use selector_parser::{ElementExt, PseudoElementCascadeType, SelectorParser};
 use selectors::Element;
 use selectors::attr::{AttrSelectorOperation, NamespaceConstraint};
-use selectors::matching::{MatchingContext, MatchingMode};
 use selectors::parser::SelectorMethods;
 use selectors::visitor::SelectorVisitor;
 use std::borrow::Cow;
@@ -601,13 +600,6 @@ impl ServoElementSnapshot {
 }
 
 impl<E: Element<Impl=SelectorImpl> + Debug> ElementExt for E {
-    fn is_link(&self) -> bool {
-        let mut context = MatchingContext::new(MatchingMode::Normal, None);
-        self.match_non_ts_pseudo_class(&NonTSPseudoClass::AnyLink,
-                                       &mut context,
-                                       &mut |_, _| {})
-    }
-
     #[inline]
     fn matches_user_and_author_rules(&self) -> bool {
         true