Method push_front

crates/common/src/linked_list.rs:154–182

Adds an element first in the list.

(&mut self, val: L::Handle)

impl<L: Link> LinkedList<L, L::Target> {
    /// Adds an element first in the list.
    pub fn push_front(&mut self, val: L::Handle) {
        // The value should not be dropped, it is being inserted into the list
        let val = ManuallyDrop::new(val);
        let ptr = L::as_raw(&val);
        assert_ne!(self.head, Some(ptr));
        unsafe {
            // Verify the node is not already in a list (pointers must be clean)
            debug_assert!(
                L::pointers(ptr).as_ref().get_prev().is_none(),
                "push_front: node already has prev pointer (double-insert?)"
            );
            debug_assert!(
                L::pointers(ptr).as_ref().get_next().is_none(),
                "push_front: node already has next pointer (double-insert?)"
            );
            L::pointers(ptr).as_mut().set_next(self.head);
            L::pointers(ptr).as_mut().set_prev(None);

            if let Some(head) = self.head {
                L::pointers(head).as_mut().set_prev(Some(ptr));
            }

            self.head = Some(ptr);

            // if self.tail.is_none() {
            //     self.tail = Some(ptr);
            // }
        }
    }

    // /// Removes the last element from a list and returns it, or None if it is
    // /// empty.