Commit fbcd4b7b authored by Alice Ryhl's avatar Alice Ryhl Committed by Miguel Ojeda
Browse files

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: default avatarAlice Ryhl <aliceryhl@google.com>
Reviewed-by: default avatarBenno Lossin <lossin@kernel.org>
Link: https://lore.kernel.org/r/20250616-rbtree-is-empty-v1-1-61f7cfb012e3@google.com


[ Adjusted title. - Miguel ]
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 03035847

rust/kernel/rbtree.rs

+6 −0
Original line number Diff line number Diff line
@@ -191,6 +191,12 @@ pub fn new() -> Self { 
        }

    }



    /// 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 {