perf: Reuse caches for nth index selectors

Author: Stranger6667

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Performance
 
 - Avoid iterating over non-Element nodes.
+- Reuse caches for nth index selectors.
 
 ## [0.11.1] - 2023-12-04
 

bindings/python/CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Performance
 
 - Avoid iterating over non-Element nodes.
+- Reuse caches for nth index selectors.
 
 ## [0.11.1] - 2023-12-09
 

bindings/ruby/CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Performance
 
 - Avoid iterating over non-Element nodes.
+- Reuse caches for nth index selectors.
 
 ## [0.11.1] - 2023-12-09
 

bindings/wasm/CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Performance
 
 - Avoid iterating over non-Element nodes.
+- Reuse caches for nth index selectors.
 
 ## [0.11.1] - 2023-12-09
 

css-inline/src/html/document.rs

@@ -8,7 +8,8 @@ use super::{
 };
 use crate::{html::DocumentStyleMap, InlineError};
 use html5ever::local_name;
-use std::{io::Write, iter::successors};
+use selectors::NthIndexCache;
+use std::{cell::RefCell, fmt, fmt::Formatter, io::Write, iter::successors};
 
 /// HTML document representation.
 ///
@@ -35,18 +36,28 @@ use std::{io::Write, iter::successors};
 ///
 /// Each Node within the `Document` is interconnected with its siblings, and has a parent-child
 /// relationship with its descendants.
-#[derive(Debug)]
 pub(crate) struct Document {
     pub(crate) nodes: Vec<Node>,
-    /// Ids of Element nodes.
-    pub(crate) elements: Vec<NodeId>,
+    /// Ids of Element nodes & caches for their nth index selectors.
+    pub(crate) elements: Vec<(NodeId, RefCell<NthIndexCache>)>,
     /// Ids of `style` nodes.
     styles: Vec<NodeId>,
     /// Ids of `link` nodes, specifically those with the `rel` attribute value set as `stylesheet`.
     /// They represent the locations (URLs) of all linked stylesheet resources in the document.
     linked_stylesheets: Vec<NodeId>,
 }
 
+impl fmt::Debug for Document {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Document")
+            .field("nodes", &self.nodes)
+            .field("styles", &self.styles)
+            .field("linked_stylesheets", &self.linked_stylesheets)
+            .finish_non_exhaustive()?;
+        Ok(())
+    }
+}
+
 impl Document {
     pub(crate) fn parse_with_options(bytes: &[u8], preallocate_node_capacity: usize) -> Document {
         parser::parse_with_options(bytes, preallocate_node_capacity)
@@ -111,7 +122,7 @@ impl Document {
 
     #[inline]
     pub(super) fn push_element_id(&mut self, node: NodeId) {
-        self.elements.push(node);
+        self.elements.push((node, RefCell::default()));
     }
 
     /// Detach a node from its siblings and its parent.

css-inline/src/html/element.rs

@@ -72,12 +72,11 @@ impl<'a> Element<'a> {
             .next_sibling
             .and_then(|node_id| self.document.as_element(node_id))
     }
-    pub(crate) fn matches(&self, selector: &Selector) -> bool {
-        let mut cache = NthIndexCache::default();
+    pub(crate) fn matches(&self, selector: &Selector, cache: &mut NthIndexCache) -> bool {
         let mut context = matching::MatchingContext::new(
             matching::MatchingMode::Normal,
             None,
-            &mut cache,
+            cache,
             QuirksMode::NoQuirks,
             matching::NeedsSelectorFlags::No,
             matching::IgnoreNthChildForInvalidation::No,

css-inline/src/html/iter.rs

@@ -5,6 +5,8 @@ use super::{
     selectors::{ParseError, Selectors},
     Specificity,
 };
+use selectors::NthIndexCache;
+use std::cell::RefCell;
 
 /// Compile selectors from a string and create an element iterator that yields elements matching these selectors.
 #[inline]
@@ -24,18 +26,18 @@ pub(crate) fn select<'a, 'b>(
 /// An internal iterator that traverses a document.
 struct Elements<'a> {
     document: &'a Document,
-    iter: std::slice::Iter<'a, NodeId>,
+    iter: std::slice::Iter<'a, (NodeId, RefCell<NthIndexCache>)>,
 }
 
 impl<'a> Iterator for Elements<'a> {
-    type Item = Element<'a>;
+    type Item = (Element<'a>, &'a RefCell<NthIndexCache>);
 
     fn next(&mut self) -> Option<Self::Item> {
-        if let Some(element_id) = self.iter.next() {
+        if let Some((element_id, cache)) = self.iter.next() {
             let NodeData::Element { element, .. } = &self.document[*element_id].data else {
                 unreachable!("Element ids always point to element nodes")
             };
-            Some(Element::new(self.document, *element_id, element))
+            Some((Element::new(self.document, *element_id, element), cache))
         } else {
             // No more elements in the document
             None
@@ -64,9 +66,10 @@ impl<'a> Iterator for Select<'a> {
     #[inline]
     fn next(&mut self) -> Option<Element<'a>> {
         // Filter the underlying iterator to only return elements that match any of the selectors
-        for element in self.elements.by_ref() {
+        for (element, cache) in self.elements.by_ref() {
+            let mut cache = cache.borrow_mut();
             for selector in self.selectors.iter() {
-                if element.matches(selector) {
+                if element.matches(selector, &mut cache) {
                     return Some(element);
                 }
             }