diff options
Diffstat (limited to 'tokio-util/src/sync/intrusive_double_linked_list.rs')
| -rw-r--r-- | tokio-util/src/sync/intrusive_double_linked_list.rs | 788 |
1 files changed, 788 insertions, 0 deletions
diff --git a/tokio-util/src/sync/intrusive_double_linked_list.rs b/tokio-util/src/sync/intrusive_double_linked_list.rs new file mode 100644 index 00000000..083fa31d --- /dev/null +++ b/tokio-util/src/sync/intrusive_double_linked_list.rs @@ -0,0 +1,788 @@ +//! An intrusive double linked list of data + +#![allow(dead_code, unreachable_pub)] + +use core::{ + marker::PhantomPinned, + ops::{Deref, DerefMut}, + ptr::NonNull, +}; + +/// A node which carries data of type `T` and is stored in an intrusive list +#[derive(Debug)] +pub struct ListNode<T> { + /// The previous node in the list. `None` if there is no previous node. + prev: Option<NonNull<ListNode<T>>>, + /// The next node in the list. `None` if there is no previous node. + next: Option<NonNull<ListNode<T>>>, + /// The data which is associated to this list item + data: T, + /// Prevents `ListNode`s from being `Unpin`. They may never be moved, since + /// the list semantics require addresses to be stable. + _pin: PhantomPinned, +} + +impl<T> ListNode<T> { + /// Creates a new node with the associated data + pub fn new(data: T) -> ListNode<T> { + Self { + prev: None, + next: None, + data, + _pin: PhantomPinned, + } + } +} + +impl<T> Deref for ListNode<T> { + type Target = T; + + fn deref(&self) -> &T { + &self.data + } +} + +impl<T> DerefMut for ListNode<T> { + fn deref_mut(&mut self) -> &mut T { + &mut self.data + } +} + +/// An intrusive linked list of nodes, where each node carries associated data +/// of type `T`. +#[derive(Debug)] +pub struct LinkedList<T> { + head: Option<NonNull<ListNode<T>>>, + tail: Option<NonNull<ListNode<T>>>, +} + +impl<T> LinkedList<T> { + /// Creates an empty linked list + pub fn new() -> Self { + LinkedList::<T> { + head: None, + tail: None, + } + } + + /// Adds a node at the front of the linked list. + /// Safety: This function is only safe as long as `node` is guaranteed to + /// get removed from the list before it gets moved or dropped. + /// In addition to this `node` may not be added to another other list before + /// it is removed from the current one. + pub unsafe fn add_front(&mut self, node: &mut ListNode<T>) { + node.next = self.head; + node.prev = None; + if let Some(mut head) = self.head { + head.as_mut().prev = Some(node.into()) + }; + self.head = Some(node.into()); + if self.tail.is_none() { + self.tail = Some(node.into()); + } + } + + /// Inserts a node into the list in a way that the list keeps being sorted. + /// Safety: This function is only safe as long as `node` is guaranteed to + /// get removed from the list before it gets moved or dropped. + /// In addition to this `node` may not be added to another other list before + /// it is removed from the current one. + pub unsafe fn add_sorted(&mut self, node: &mut ListNode<T>) + where + T: PartialOrd, + { + if self.head.is_none() { + // First node in the list + self.head = Some(node.into()); + self.tail = Some(node.into()); + return; + } + + let mut prev: Option<NonNull<ListNode<T>>> = None; + let mut current = self.head; + + while let Some(mut current_node) = current { + if node.data < current_node.as_ref().data { + // Need to insert before the current node + current_node.as_mut().prev = Some(node.into()); + match prev { + Some(mut prev) => { + prev.as_mut().next = Some(node.into()); + } + None => { + // We are inserting at the beginning of the list + self.head = Some(node.into()); + } + } + node.next = current; + node.prev = prev; + return; + } + prev = current; + current = current_node.as_ref().next; + } + + // We looped through the whole list and the nodes data is bigger or equal + // than everything we found up to now. + // Insert at the end. Since we checked before that the list isn't empty, + // tail always has a value. + node.prev = self.tail; + node.next = None; + self.tail.as_mut().unwrap().as_mut().next = Some(node.into()); + self.tail = Some(node.into()); + } + + /// Returns the first node in the linked list without removing it from the list + /// The function is only safe as long as valid pointers are stored inside + /// the linked list. + /// The returned pointer is only guaranteed to be valid as long as the list + /// is not mutated + pub fn peek_first(&self) -> Option<&mut ListNode<T>> { + // Safety: When the node was inserted it was promised that it is alive + // until it gets removed from the list. + // The returned node has a pointer which constrains it to the lifetime + // of the list. This is ok, since the Node is supposed to outlive + // its insertion in the list. + unsafe { + self.head + .map(|mut node| &mut *(node.as_mut() as *mut ListNode<T>)) + } + } + + /// Returns the last node in the linked list without removing it from the list + /// The function is only safe as long as valid pointers are stored inside + /// the linked list. + /// The returned pointer is only guaranteed to be valid as long as the list + /// is not mutated + pub fn peek_last(&self) -> Option<&mut ListNode<T>> { + // Safety: When the node was inserted it was promised that it is alive + // until it gets removed from the list. + // The returned node has a pointer which constrains it to the lifetime + // of the list. This is ok, since the Node is supposed to outlive + // its insertion in the list. + unsafe { + self.tail + .map(|mut node| &mut *(node.as_mut() as *mut ListNode<T>)) + } + } + + /// Removes the first node from the linked list + pub fn remove_first(&mut self) -> Option<&mut ListNode<T>> { + #![allow(clippy::debug_assert_with_mut_call)] + + // Safety: When the node was inserted it was promised that it is alive + // until it gets removed from the list + unsafe { + let mut head = self.head?; + self.head = head.as_mut().next; + + let first_ref = head.as_mut(); + match first_ref.next { + None => { + // This was the only node in the list + debug_assert_eq!(Some(first_ref.into()), self.tail); + self.tail = None; + } + Some(mut next) => { + next.as_mut().prev = None; + } + } + + first_ref.prev = None; + first_ref.next = None; + Some(&mut *(first_ref as *mut ListNode<T>)) + } + } + + /// Removes the last node from the linked list and returns it + pub fn remove_last(&mut self) -> Option<&mut ListNode<T>> { + #![allow(clippy::debug_assert_with_mut_call)] + + // Safety: When the node was inserted it was promised that it is alive + // until it gets removed from the list + unsafe { + let mut tail = self.tail?; + self.tail = tail.as_mut().prev; + + let last_ref = tail.as_mut(); + match last_ref.prev { + None => { + // This was the last node in the list + debug_assert_eq!(Some(last_ref.into()), self.head); + self.head = None; + } + Some(mut prev) => { + prev.as_mut().next = None; + } + } + + last_ref.prev = None; + last_ref.next = None; + Some(&mut *(last_ref as *mut ListNode<T>)) + } + } + + /// Returns whether the linked list doesn not contain any node + pub fn is_empty(&self) -> bool { + if self.head.is_some() { + return false; + } + + debug_assert!(self.tail.is_none()); + true + } + + /// Removes the given `node` from the linked list. + /// Returns whether the `node` was removed. + /// It is also only safe if it is known that the `node` is either part of this + /// list, or of no list at all. If `node` is part of another list, the + /// behavior is undefined. + pub unsafe fn remove(&mut self, node: &mut ListNode<T>) -> bool { + #![allow(clippy::debug_assert_with_mut_call)] + + match node.prev { + None => { + // This might be the first node in the list. If it is not, the + // node is not in the list at all. Since our precondition is that + // the node must either be in this list or in no list, we check that + // the node is really in no list. + if self.head != Some(node.into()) { + debug_assert!(node.next.is_none()); + return false; + } + self.head = node.next; + } + Some(mut prev) => { + debug_assert_eq!(prev.as_ref().next, Some(node.into())); + prev.as_mut().next = node.next; + } + } + + match node.next { + None => { + // This must be the last node in our list. Otherwise the list + // is inconsistent. + debug_assert_eq!(self.tail, Some(node.into())); + self.tail = node.prev; + } + Some(mut next) => { + debug_assert_eq!(next.as_mut().prev, Some(node.into())); + next.as_mut().prev = node.prev; + } + } + + node.next = None; + node.prev = None; + + true + } + + /// Drains the list iby calling a callback on each list node + /// + /// The method does not return an iterator since stopping or deferring + /// draining the list is not permitted. If the method would push nodes to + /// an iterator we could not guarantee that the nodes do not get utilized + /// after having been removed from the list anymore. + pub fn drain<F>(&mut self, mut func: F) + where + F: FnMut(&mut ListNode<T>), + { + let mut current = self.head; + self.head = None; + self.tail = None; + + while let Some(mut node) = current { + // Safety: The nodes have not been removed from the list yet and must + // therefore contain valid data. The nodes can also not be added to + // the list again during iteration, since the list is mutably borrowed. + unsafe { + let node_ref = node.as_mut(); + current = node_ref.next; + + node_ref.next = None; + node_ref.prev = None; + + // Note: We do not reset the pointers from the next element in the + // list to the current one since we will iterate over the whole + // list anyway, and therefore clean up all pointers. + + func(node_ref); + } + } + } + + /// Drains the list in reverse order by calling a callback on each list node + /// + /// The method does not return an iterator since stopping or deferring + /// draining the list is not permitted. If the method would push nodes to + /// an iterator we could not guarantee that the nodes do not get utilized + /// after having been removed from the list anymore. + pub fn reverse_drain<F>(&mut self, mut func: F) + where + F: FnMut(&mut ListNode<T>), + { + let mut current = self.tail; + self.head = None; + self.tail = None; + + while let Some(mut node) = current { + // Safety: The nodes have not been removed from the list yet and must + // therefore contain valid data. The nodes can also not be added to + // the list again during iteration, since the list is mutably borrowed. + unsafe { + let node_ref = node.as_mut(); + current = node_ref.prev; + + node_ref.next = None; + node_ref.prev = None; + + // Note: We do not reset the pointers from the next element in the + // list to the current one since we will iterate over the whole + // list anyway, and therefore clean up all pointers. + + func(node_ref); + } + } + } +} + +#[cfg(all(test, feature = "std"))] // Tests make use of Vec at the moment +mod tests { + use super::*; + + fn collect_list<T: Copy>(mut list: LinkedList<T>) -> Vec<T> { + let mut result = Vec::new(); + list.drain(|node| { + result.push(**node); + }); + result + } + + fn collect_reverse_list<T: Copy>(mut list: LinkedList<T>) -> Vec<T> { + let mut result = Vec::new(); + list.reverse_drain(|node| { + result.push(**node); + }); + result + } + + unsafe fn add_nodes(list: &mut LinkedList<i32>, nodes: &mut [&mut ListNode<i32>]) { + for node in nodes.iter_mut() { + list.add_front(node); + } + } + + unsafe fn assert_clean<T>(node: &mut ListNode<T>) { + assert!(node.next.is_none()); + assert!(node.prev.is_none()); + } + + #[test] + fn insert_and_iterate() { + unsafe { + let mut a = ListNode::new(5); + let mut b = ListNode::new(7); + let mut c = ListNode::new(31); + + let mut setup = |list: &mut LinkedList<i32>| { + assert_eq!(true, list.is_empty()); + list.add_front(&mut c); + assert_eq!(31, **list.peek_first().unwrap()); + assert_eq!(false, list.is_empty()); + list.add_front(&mut b); + assert_eq!(7, **list.peek_first().unwrap()); + list.add_front(&mut a); + assert_eq!(5, **list.peek_first().unwrap()); + }; + + let mut list = LinkedList::new(); + setup(&mut list); + let items: Vec<i32> = collect_list(list); + assert_eq!([5, 7, 31].to_vec(), items); + + let mut list = LinkedList::new(); + setup(&mut list); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([31, 7, 5].to_vec(), items); + } + } + + #[test] + fn add_sorted() { + unsafe { + let mut a = ListNode::new(5); + let mut b = ListNode::new(7); + let mut c = ListNode::new(31); + let mut d = ListNode::new(99); + + let mut list = LinkedList::new(); + list.add_sorted(&mut a); + let items: Vec<i32> = collect_list(list); + assert_eq!([5].to_vec(), items); + + let mut list = LinkedList::new(); + list.add_sorted(&mut a); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([5].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut d, &mut c, &mut b]); + list.add_sorted(&mut a); + let items: Vec<i32> = collect_list(list); + assert_eq!([5, 7, 31, 99].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut d, &mut c, &mut b]); + list.add_sorted(&mut a); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([99, 31, 7, 5].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut d, &mut c, &mut a]); + list.add_sorted(&mut b); + let items: Vec<i32> = collect_list(list); + assert_eq!([5, 7, 31, 99].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut d, &mut c, &mut a]); + list.add_sorted(&mut b); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([99, 31, 7, 5].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut d, &mut b, &mut a]); + list.add_sorted(&mut c); + let items: Vec<i32> = collect_list(list); + assert_eq!([5, 7, 31, 99].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut d, &mut b, &mut a]); + list.add_sorted(&mut c); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([99, 31, 7, 5].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + list.add_sorted(&mut d); + let items: Vec<i32> = collect_list(list); + assert_eq!([5, 7, 31, 99].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + list.add_sorted(&mut d); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([99, 31, 7, 5].to_vec(), items); + } + } + + #[test] + fn drain_and_collect() { + unsafe { + let mut a = ListNode::new(5); + let mut b = ListNode::new(7); + let mut c = ListNode::new(31); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + + let taken_items: Vec<i32> = collect_list(list); + assert_eq!([5, 7, 31].to_vec(), taken_items); + } + } + + #[test] + fn peek_last() { + unsafe { + let mut a = ListNode::new(5); + let mut b = ListNode::new(7); + let mut c = ListNode::new(31); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + + let last = list.peek_last(); + assert_eq!(31, **last.unwrap()); + list.remove_last(); + + let last = list.peek_last(); + assert_eq!(7, **last.unwrap()); + list.remove_last(); + + let last = list.peek_last(); + assert_eq!(5, **last.unwrap()); + list.remove_last(); + + let last = list.peek_last(); + assert!(last.is_none()); + } + } + + #[test] + fn remove_first() { + unsafe { + // We iterate forward and backwards through the manipulated lists + // to make sure pointers in both directions are still ok. + let mut a = ListNode::new(5); + let mut b = ListNode::new(7); + let mut c = ListNode::new(31); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + let removed = list.remove_first().unwrap(); + assert_clean(removed); + assert!(!list.is_empty()); + let items: Vec<i32> = collect_list(list); + assert_eq!([7, 31].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + let removed = list.remove_first().unwrap(); + assert_clean(removed); + assert!(!list.is_empty()); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([31, 7].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut b, &mut a]); + let removed = list.remove_first().unwrap(); + assert_clean(removed); + assert!(!list.is_empty()); + let items: Vec<i32> = collect_list(list); + assert_eq!([7].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut b, &mut a]); + let removed = list.remove_first().unwrap(); + assert_clean(removed); + assert!(!list.is_empty()); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([7].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut a]); + let removed = list.remove_first().unwrap(); + assert_clean(removed); + assert!(list.is_empty()); + let items: Vec<i32> = collect_list(list); + assert!(items.is_empty()); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut a]); + let removed = list.remove_first().unwrap(); + assert_clean(removed); + assert!(list.is_empty()); + let items: Vec<i32> = collect_reverse_list(list); + assert!(items.is_empty()); + } + } + + #[test] + fn remove_last() { + unsafe { + // We iterate forward and backwards through the manipulated lists + // to make sure pointers in both directions are still ok. + let mut a = ListNode::new(5); + let mut b = ListNode::new(7); + let mut c = ListNode::new(31); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + let removed = list.remove_last().unwrap(); + assert_clean(removed); + assert!(!list.is_empty()); + let items: Vec<i32> = collect_list(list); + assert_eq!([5, 7].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + let removed = list.remove_last().unwrap(); + assert_clean(removed); + assert!(!list.is_empty()); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([7, 5].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut b, &mut a]); + let removed = list.remove_last().unwrap(); + assert_clean(removed); + assert!(!list.is_empty()); + let items: Vec<i32> = collect_list(list); + assert_eq!([5].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut b, &mut a]); + let removed = list.remove_last().unwrap(); + assert_clean(removed); + assert!(!list.is_empty()); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([5].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut a]); + let removed = list.remove_last().unwrap(); + assert_clean(removed); + assert!(list.is_empty()); + let items: Vec<i32> = collect_list(list); + assert!(items.is_empty()); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut a]); + let removed = list.remove_last().unwrap(); + assert_clean(removed); + assert!(list.is_empty()); + let items: Vec<i32> = collect_reverse_list(list); + assert!(items.is_empty()); + } + } + + #[test] + fn remove_by_address() { + unsafe { + let mut a = ListNode::new(5); + let mut b = ListNode::new(7); + let mut c = ListNode::new(31); + + { + // Remove first + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + assert_eq!(true, list.remove(&mut a)); + assert_clean((&mut a).into()); + // a should be no longer there and can't be removed twice + assert_eq!(false, list.remove(&mut a)); + assert_eq!(Some((&mut b).into()), list.head); + assert_eq!(Some((&mut c).into()), b.next); + assert_eq!(Some((&mut b).into()), c.prev); + let items: Vec<i32> = collect_list(list); + assert_eq!([7, 31].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + assert_eq!(true, list.remove(&mut a)); + assert_clean((&mut a).into()); + // a should be no longer there and can't be removed twice + assert_eq!(false, list.remove(&mut a)); + assert_eq!(Some((&mut c).into()), b.next); + assert_eq!(Some((&mut b).into()), c.prev); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([31, 7].to_vec(), items); + } + + { + // Remove middle + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + assert_eq!(true, list.remove(&mut b)); + assert_clean((&mut b).into()); + assert_eq!(Some((&mut c).into()), a.next); + assert_eq!(Some((&mut a).into()), c.prev); + let items: Vec<i32> = collect_list(list); + assert_eq!([5, 31].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + assert_eq!(true, list.remove(&mut b)); + assert_clean((&mut b).into()); + assert_eq!(Some((&mut c).into()), a.next); + assert_eq!(Some((&mut a).into()), c.prev); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([31, 5].to_vec(), items); + } + + { + // Remove last + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + assert_eq!(true, list.remove(&mut c)); + assert_clean((&mut c).into()); + assert!(b.next.is_none()); + assert_eq!(Some((&mut b).into()), list.tail); + let items: Vec<i32> = collect_list(list); + assert_eq!([5, 7].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut c, &mut b, &mut a]); + assert_eq!(true, list.remove(&mut c)); + assert_clean((&mut c).into()); + assert!(b.next.is_none()); + assert_eq!(Some((&mut b).into()), list.tail); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([7, 5].to_vec(), items); + } + + { + // Remove first of two + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut b, &mut a]); + assert_eq!(true, list.remove(&mut a)); + assert_clean((&mut a).into()); + // a should be no longer there and can't be removed twice + assert_eq!(false, list.remove(&mut a)); + assert_eq!(Some((&mut b).into()), list.head); + assert_eq!(Some((&mut b).into()), list.tail); + assert!(b.next.is_none()); + assert!(b.prev.is_none()); + let items: Vec<i32> = collect_list(list); + assert_eq!([7].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut b, &mut a]); + assert_eq!(true, list.remove(&mut a)); + assert_clean((&mut a).into()); + // a should be no longer there and can't be removed twice + assert_eq!(false, list.remove(&mut a)); + assert_eq!(Some((&mut b).into()), list.head); + assert_eq!(Some((&mut b).into()), list.tail); + assert!(b.next.is_none()); + assert!(b.prev.is_none()); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([7].to_vec(), items); + } + + { + // Remove last of two + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut b, &mut a]); + assert_eq!(true, list.remove(&mut b)); + assert_clean((&mut b).into()); + assert_eq!(Some((&mut a).into()), list.head); + assert_eq!(Some((&mut a).into()), list.tail); + assert!(a.next.is_none()); + assert!(a.prev.is_none()); + let items: Vec<i32> = collect_list(list); + assert_eq!([5].to_vec(), items); + + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut b, &mut a]); + assert_eq!(true, list.remove(&mut b)); + assert_clean((&mut b).into()); + assert_eq!(Some((&mut a).into()), list.head); + assert_eq!(Some((&mut a).into()), list.tail); + assert!(a.next.is_none()); + assert!(a.prev.is_none()); + let items: Vec<i32> = collect_reverse_list(list); + assert_eq!([5].to_vec(), items); + } + + { + // Remove last item + let mut list = LinkedList::new(); + add_nodes(&mut list, &mut [&mut a]); + assert_eq!(true, list.remove(&mut a)); + assert_clean((&mut a).into()); + assert!(list.head.is_none()); + assert!(list.tail.is_none()); + let items: Vec<i32> = collect_list(list); + assert!(items.is_empty()); + } + + { + // Remove missing + let mut list = LinkedList::new(); + list.add_front(&mut b); + list.add_front(&mut a); + assert_eq!(false, list.remove(&mut c)); + } + } + } +} |