From fbcd4b7bf5c92f7d456eefcecac518023357cea4 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Mon, 16 Jun 2025 10:36:21 +0000 Subject: [PATCH] rust: rbtree: add RBTree::is_empty In Rust Binder I need to be able to determine whether a red/black tree is empty. Thus, add a method for that operation to replace rbtree.iter().next().is_none() This is terrible, so add a method for this purpose. We do not add a RBTree::len method because computing the number of elements requires iterating the entire tree, but checking whether it is empty can be done cheaply. Signed-off-by: Alice Ryhl Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250616-rbtree-is-empty-v1-1-61f7cfb012e3@google.com [ Adjusted title. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/rbtree.rs | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs index 8d978c8967475..9457134eb3afd 100644 --- a/rust/kernel/rbtree.rs +++ b/rust/kernel/rbtree.rs @@ -191,6 +191,12 @@ impl RBTree { } } + /// Returns true if this tree is empty. + #[inline] + pub fn is_empty(&self) -> bool { + self.root.rb_node.is_null() + } + /// Returns an iterator over the tree nodes, sorted by key. pub fn iter(&self) -> Iter<'_, K, V> { Iter { -- 2.47.2