perf: Simplify iteration over nodes

Author: Stranger6667

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Performance
+
+- Use a simpler way for HTML tree traversal.
+
 ## [0.10.0] - 2023-06-16
 
 ### Added

bindings/python/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Performance
+
+- Use a simpler way for HTML tree traversal.
+
 ## [0.10.0] - 2023-06-16
 
 ### Added

bindings/ruby/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Performance
+
+- Use a simpler way for HTML tree traversal.
+
 ## 0.10.0 - 2023-06-17
 
 - Initial public release

bindings/wasm/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Performance
+
+- Use a simpler way for HTML tree traversal.
+
 ## [0.10.0] - 2023-06-16
 
 ### Added

css-inline/src/html/document.rs

@@ -61,6 +61,12 @@ impl Document {
         }
     }
 
+    #[inline]
+    pub(super) fn next_node_id(&self, node_id: NodeId) -> Option<NodeId> {
+        node_id.next().filter(|&next| next.get() < self.nodes.len())
+    }
+
+    #[inline]
     pub(super) fn as_element(&self, node_id: NodeId) -> Option<Element<'_>> {
         if let NodeData::Element { element, .. } = &self[node_id].data {
             Some(Element::new(self, node_id, element))
@@ -246,17 +252,6 @@ impl Document {
         successors(self[node].first_child, |&node| self[node].next_sibling)
     }
 
-    pub(crate) fn node_and_ancestors(&self, node: NodeId) -> impl Iterator<Item = NodeId> + '_ {
-        successors(Some(node), move |&node| self[node].parent)
-    }
-
-    pub(crate) fn next_in_tree_order(&self, node: NodeId) -> Option<NodeId> {
-        self[node].first_child.or_else(|| {
-            self.node_and_ancestors(node)
-                .find_map(|ancestor| self[ancestor].next_sibling)
-        })
-    }
-
     /// Serialize the document to HTML string.
     pub(crate) fn serialize<W: Write>(
         &self,

css-inline/src/html/iter.rs

@@ -15,17 +15,17 @@ pub(crate) fn select<'a, 'b>(
     Selectors::compile(selectors).map(|selectors| Select {
         traverse: Traverse {
             document,
-            current: Some(NodeId::document_id()),
+            current: NodeId::document_id(),
         },
         selectors,
     })
 }
 
-/// An internal iterator that traverses a document in tree order.
+/// An internal iterator that traverses a document.
 struct Traverse<'a> {
     document: &'a Document,
     // Current node being processed
-    current: Option<NodeId>,
+    current: NodeId,
 }
 
 impl<'a> Iterator for Traverse<'a> {
@@ -34,11 +34,10 @@ impl<'a> Iterator for Traverse<'a> {
     fn next(&mut self) -> Option<Self::Item> {
         // Loop until we either run out of nodes or find an element node
         loop {
-            if let Some(current) = self.current {
-                // Advance to the next node in tree order
-                self.current = self.document.next_in_tree_order(current);
+            if let Some(next) = self.document.next_node_id(self.current) {
+                self.current = next;
                 // If the current node is an element node, return it, else continue with the loop
-                if let Some(element) = self.document.as_element(current) {
+                if let Some(element) = self.document.as_element(next) {
                     return Some(element);
                 }
             } else {

css-inline/src/html/node.rs

@@ -65,9 +65,14 @@ impl NodeId {
     pub(super) fn document_id() -> NodeId {
         NodeId::new(1)
     }
+    #[inline]
     pub(super) fn get(self) -> usize {
         self.0.get()
     }
+    #[inline]
+    pub(super) fn next(self) -> Option<NodeId> {
+        self.get().checked_add(1).map(NodeId::new)
+    }
 }
 
 /// Data associated with a `Node`.