Reuse Vec in children iterator cache

nicoburns · nicoburns · commit eda4487d82d9 · 2023-09-25T21:21:00.000+01:00
diff --git a/src/tree/taffy_tree/tree.rs b/src/tree/taffy_tree/tree.rs
@@ -100,9 +100,9 @@ impl LayoutTree for Taffy {
     fn children(&self, node: NodeId) -> Self::ChildIter<'_> {
         let mut cache = self.node_children_cache.borrow_mut();
         if cache.0 != node {
-            let mut children = Vec::with_capacity(self.children.len());
-            find_children_recursive(&mut children, self, node);
-            *cache = (node, children);
+            cache.1.clear();
+            cache.0 = node;
+            find_children_recursive(&mut cache.1, self, node);
         }
         RefCellVecIter { children: RefMut::map(cache, |c| &mut c.1), index: 0 }
     }

Original file line number	Diff line number	Diff line change
`@@ -100,9 +100,9 @@ impl LayoutTree for Taffy {`
`100`	`100`	`fn children(&self, node: NodeId) -> Self::ChildIter<'_> {`
`101`	`101`	`let mut cache = self.node_children_cache.borrow_mut();`
`102`	`102`	`if cache.0 != node {`
`103`		`- let mut children = Vec::with_capacity(self.children.len());`
`104`		`- find_children_recursive(&mut children, self, node);`
`105`		`- *cache = (node, children);`
	`103`	`+ cache.1.clear();`
	`104`	`+ cache.0 = node;`
	`105`	`+ find_children_recursive(&mut cache.1, self, node);`
`106`	`106`	`}`
`107`	`107`	`RefCellVecIter { children: RefMut::map(cache, \|c\| &mut c.1), index: 0 }`
`108`	`108`	`}`