fn get_dir_index()

in src/index.rs [278:307]

• 23 lines of code
• 6 McCabe index (conditional complexity)

    fn get_dir_index(&self, dir: ChildDir) -> Option<TreeIndex> {
        let mut opp_dir = ChildDir::Left;
        let mut dir_bit = 1;
        if dir == ChildDir::Left {
            opp_dir = ChildDir::Right;
            dir_bit = 0;
        }

        // Gets the closest ancestor that has a dir child not on the path from the root to the input index.
        // Retrieve the dir child, which is the root of the subtree that contains the dir index.
        let mut index = *self;
        for i in (0..self.height).rev() {
            if self.get_bit(i) == 1 - dir_bit {
                index = index.get_prefix(i).get_child_index_by_dir(dir);
                break;
            }
        }
        // Gets the opp_dir-most child, which is the desired index.
        while index.get_height() < self.height {
            index = index.get_child_index_by_dir(opp_dir);
        }

        if index == *self {
            // If the result index is the same as the input, the input is the dir-most leaf.
            // So the dir node to the input doesn't exist, return None.
            None
        } else {
            Some(index)
        }
    }