Method empty_node

cranelift/bforest/src/path.rs:563–589

The current node at `level` has become empty. Remove the node from its parent node and leave the path in a normalized state. This means that the path at this level will go through the right sibling of this node. If the current node has no right sibling, set `self.size = 0`. Returns true if the tree becomes empty.

(&mut self, level: usize, pool: &mut NodePool<F>)

    ///
    /// Returns true if the tree becomes empty.
    fn empty_node(&mut self, level: usize, pool: &mut NodePool<F>) -> bool {
        pool.free_node(self.node[level]);
        if level == 0 {
            // We just deleted the root node, so the tree is now empty.
            return true;
        }

        // Get the right sibling node before recursively removing nodes.
        let rhs_node = self.right_sibling(level, pool).map(|(_, n)| n);

        // Remove the current sub-tree from the parent node.
        let pl = level - 1;
        let pe = self.entry[pl].into();
        let status = pool[self.node[pl]].inner_remove(pe);
        self.heal_level(status, pl, pool);

        // Finally update the path at this level.
        match rhs_node {
            // We'll leave `self.entry[level]` unchanged. It can be non-zero after moving node
            // entries to the right sibling node.
            Some(rhs) => self.node[level] = rhs,
            // We have no right sibling, so we must have deleted the right-most
            // entry. The path should be moved to the "off-the-end" position.
            None => self.size = 0,
        }
        false
    }

    /// Find the level where the right sibling to the current node at `level` branches off.
    ///