style: Add a document state invalidator.

components/style/invalidation/element/document_state.rs

@@ -0,0 +1,98 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! An invalidation processor for style changes due to document state changes.
+
+use dom::TElement;
+use element_state::DocumentState;
+use invalidation::element::invalidator::{DescendantInvalidationLists, InvalidationVector};
+use invalidation::element::invalidator::{Invalidation, InvalidationProcessor};
+use invalidation::element::state_and_attributes;
+use selectors::matching::{MatchingContext, MatchingMode, QuirksMode, VisitedHandlingMode};
+use stylist::StyleRuleCascadeData;
+
+/// A struct holding the members necessary to invalidate document state
+/// selectors.
+pub struct InvalidationMatchingData {
+    /// The document state that has changed, which makes it always match.
+    pub document_state: DocumentState,
+}
+
+/// An invalidation processor for style changes due to state and attribute
+/// changes.
+pub struct DocumentStateInvalidationProcessor<'a, E: TElement> {
+    rules: &'a StyleRuleCascadeData,
+    matching_context: MatchingContext<'a, E::Impl>,
+    document_states_changed: DocumentState,
+}
+
+impl<'a, E: TElement> DocumentStateInvalidationProcessor<'a, E> {
+    /// Creates a new DocumentStateInvalidationProcessor.
+    #[inline]
+    pub fn new(
+        rules: &'a StyleRuleCascadeData,
+        document_states_changed: DocumentState,
+        quirks_mode: QuirksMode,
+    ) -> Self {
+        let mut matching_context = MatchingContext::new_for_visited(
+            MatchingMode::Normal,
+            None,
+            None,
+            VisitedHandlingMode::AllLinksVisitedAndUnvisited,
+            quirks_mode,
+        );
+
+        matching_context.extra_data = Some(InvalidationMatchingData {
+            document_state: document_states_changed,
+        });
+
+        Self { rules, document_states_changed, matching_context }
+    }
+}
+
+impl<'a, E: TElement> InvalidationProcessor<'a, E> for DocumentStateInvalidationProcessor<'a, E> {
+    fn collect_invalidations(
+        &mut self,
+        _element: E,
+        self_invalidations: &mut InvalidationVector<'a>,
+        _descendant_invalidations: &mut DescendantInvalidationLists<'a>,
+        _sibling_invalidations: &mut InvalidationVector<'a>,
+    ) -> bool {
+        let map = self.rules.invalidation_map();
+
+        for dependency in &map.document_state_selectors {
+            if !dependency.state.intersects(self.document_states_changed) {
+                continue;
+            }
+
+            self_invalidations.push(Invalidation::new(&dependency.selector, 0));
+        }
+
+        false
+    }
+
+    fn matching_context(&mut self) -> &mut MatchingContext<'a, E::Impl> {
+        &mut self.matching_context
+    }
+
+    fn recursion_limit_exceeded(&mut self, _: E) {
+        unreachable!("We don't run document state invalidation with stack limits")
+    }
+
+    fn should_process_descendants(&mut self, element: E) -> bool {
+        let data = match element.borrow_data() {
+            Some(d) => d,
+            None => return false,
+        };
+        state_and_attributes::should_process_descendants(&data)
+    }
+
+    fn invalidated_descendants(&mut self, element: E, child: E) {
+        state_and_attributes::invalidated_descendants(element, child)
+    }
+
+    fn invalidated_self(&mut self, element: E) {
+        state_and_attributes::invalidated_self(element);
+    }
+}