linked_list_pop.rs

impl<T> LinkedList<T> {
    /// Pop element from the back of LinkedList, or return `None` if empty
    #[inline]
    pub fn pop_back(&mut self) -> Option<T> {
        self.pop_back_node().map(Node::into_element)
    }

    /// Pop node from the back of LinkedList, or return `None` if empty
    /// This will unlink the last node from LinkedList
    #[inline]
    fn pop_back_node(&mut self) -> Option<Box<Node<T>>> {
        self.tail.map(|node_ptr| {
            unsafe {
                if self.length > 1 {
                    self.tail = self.get_ith_node(self.head, self.length - 2);
                } else {
                    self.tail = None;
                }
                match self.tail {
                    None => self.head = None,
                    Some(mut tail) => {
                        tail.as_mut().next = None;
                    }
                }
            }

            self.length -= 1;
            let node = unsafe { Box::from_raw(node_ptr.as_ptr()) };
            node
        })
    }
}