perf: Drop intermediate iterator

Author: Stranger6667

css-inline/src/html/iter.rs

@@ -15,39 +15,16 @@ pub(crate) fn select<'a, 'b>(
     selectors: &'b str,
 ) -> Result<Select<'a>, ParseError<'b>> {
     Selectors::compile(selectors).map(|selectors| Select {
-        elements: Elements {
-            document,
-            iter: document.elements.iter(),
-        },
+        document,
+        iter: document.elements.iter(),
         selectors,
     })
 }
 
-/// An internal iterator that traverses a document.
-struct Elements<'a> {
-    document: &'a Document,
-    iter: std::slice::Iter<'a, (NodeId, RefCell<NthIndexCache>)>,
-}
-
-impl<'a> Iterator for Elements<'a> {
-    type Item = (Element<'a>, &'a RefCell<NthIndexCache>);
-
-    fn next(&mut self) -> Option<Self::Item> {
-        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), cache))
-        } else {
-            // No more elements in the document
-            None
-        }
-    }
-}
-
 /// An element iterator adaptor that yields elements matching given selectors.
 pub(crate) struct Select<'a> {
-    elements: Elements<'a>,
+    document: &'a Document,
+    iter: std::slice::Iter<'a, (NodeId, RefCell<NthIndexCache>)>,
     /// The selectors to be matched.
     selectors: Selectors,
 }
@@ -65,8 +42,11 @@ 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, cache) in self.elements.by_ref() {
+        for (element_id, cache) in self.iter.by_ref() {
+            let NodeData::Element { element, .. } = &self.document[*element_id].data else {
+                unreachable!("Element ids always point to element nodes")
+            };
+            let element = Element::new(self.document, *element_id, element);
             let mut cache = cache.borrow_mut();
             for selector in self.selectors.iter() {
                 if element.matches(selector, &mut cache) {