diff --git a/src/liballoc/collections/linked_list.rs b/src/liballoc/collections/linked_list.rs index 29bf2fdb30cf7..b88ca8a0fb0d1 100644 --- a/src/liballoc/collections/linked_list.rs +++ b/src/liballoc/collections/linked_list.rs @@ -242,6 +242,121 @@ impl LinkedList { self.len -= 1; } + + /// Splices a series of nodes between two existing nodes. + /// + /// Warning: this will not check that the provided node belongs to the two existing lists. + #[inline] + unsafe fn splice_nodes( + &mut self, + existing_prev: Option>>, + existing_next: Option>>, + mut splice_start: NonNull>, + mut splice_end: NonNull>, + splice_length: usize, + ) { + // This method takes care not to create multiple mutable references to whole nodes at the same time, + // to maintain validity of aliasing pointers into `element`. + if let Some(mut existing_prev) = existing_prev { + existing_prev.as_mut().next = Some(splice_start); + } else { + self.head = Some(splice_start); + } + if let Some(mut existing_next) = existing_next { + existing_next.as_mut().prev = Some(splice_end); + } else { + self.tail = Some(splice_end); + } + splice_start.as_mut().prev = existing_prev; + splice_end.as_mut().next = existing_next; + + self.len += splice_length; + } + + /// Detaches all nodes from a linked list as a series of nodes. + #[inline] + fn detach_all_nodes(mut self) -> Option<(NonNull>, NonNull>, usize)> { + let head = self.head.take(); + let tail = self.tail.take(); + let len = mem::replace(&mut self.len, 0); + if let Some(head) = head { + let tail = tail.unwrap_or_else(|| unsafe { core::hint::unreachable_unchecked() }); + Some((head, tail, len)) + } else { + None + } + } + + #[inline] + unsafe fn split_off_before_node( + &mut self, + split_node: Option>>, + at: usize, + ) -> Self { + // The split node is the new head node of the second part + if let Some(mut split_node) = split_node { + let first_part_head; + let first_part_tail; + first_part_tail = split_node.as_mut().prev.take(); + if let Some(mut tail) = first_part_tail { + tail.as_mut().next = None; + first_part_head = self.head; + } else { + first_part_head = None; + } + + let first_part = LinkedList { + head: first_part_head, + tail: first_part_tail, + len: at, + marker: PhantomData, + }; + + // Fix the head ptr of the second part + self.head = Some(split_node); + self.len = self.len - at; + + first_part + } else { + mem::replace(self, LinkedList::new()) + } + } + + #[inline] + unsafe fn split_off_after_node( + &mut self, + split_node: Option>>, + at: usize, + ) -> Self { + // The split node is the new tail node of the first part and owns + // the head of the second part. + if let Some(mut split_node) = split_node { + let second_part_head; + let second_part_tail; + second_part_head = split_node.as_mut().next.take(); + if let Some(mut head) = second_part_head { + head.as_mut().prev = None; + second_part_tail = self.tail; + } else { + second_part_tail = None; + } + + let second_part = LinkedList { + head: second_part_head, + tail: second_part_tail, + len: self.len - at, + marker: PhantomData, + }; + + // Fix the tail ptr of the first part + self.tail = Some(split_node); + self.len = at; + + second_part + } else { + mem::replace(self, LinkedList::new()) + } + } } #[stable(feature = "rust1", since = "1.0.0")] @@ -319,6 +434,27 @@ impl LinkedList { } } + /// Moves all elements from `other` to the begin of the list. + #[unstable(feature = "linked_list_prepend", issue = "none")] + pub fn prepend(&mut self, other: &mut Self) { + match self.head { + None => mem::swap(self, other), + Some(mut head) => { + // `as_mut` is okay here because we have exclusive access to the entirety + // of both lists. + if let Some(mut other_tail) = other.tail.take() { + unsafe { + head.as_mut().prev = Some(other_tail); + other_tail.as_mut().next = Some(head); + } + + self.head = other.head.take(); + self.len += mem::replace(&mut other.len, 0); + } + } + } + } + /// Provides a forward iterator. /// /// # Examples @@ -373,6 +509,42 @@ impl LinkedList { IterMut { head: self.head, tail: self.tail, len: self.len, list: self } } + /// Provides a cursor at the front element. + /// + /// The cursor is pointing to the "ghost" non-element if the list is empty. + #[inline] + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn cursor_front(&self) -> Cursor<'_, T> { + Cursor { index: 0, current: self.head, list: self } + } + + /// Provides a cursor with editing operations at the front element. + /// + /// The cursor is pointing to the "ghost" non-element if the list is empty. + #[inline] + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn cursor_front_mut(&mut self) -> CursorMut<'_, T> { + CursorMut { index: 0, current: self.head, list: self } + } + + /// Provides a cursor at the back element. + /// + /// The cursor is pointing to the "ghost" non-element if the list is empty. + #[inline] + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn cursor_back(&self) -> Cursor<'_, T> { + Cursor { index: self.len.checked_sub(1).unwrap_or(0), current: self.tail, list: self } + } + + /// Provides a cursor with editing operations at the back element. + /// + /// The cursor is pointing to the "ghost" non-element if the list is empty. + #[inline] + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn cursor_back_mut(&mut self) -> CursorMut<'_, T> { + CursorMut { index: self.len.checked_sub(1).unwrap_or(0), current: self.tail, list: self } + } + /// Returns `true` if the `LinkedList` is empty. /// /// This operation should compute in O(1) time. @@ -703,30 +875,7 @@ impl LinkedList { } iter.tail }; - - // The split node is the new tail node of the first part and owns - // the head of the second part. - let second_part_head; - - unsafe { - second_part_head = split_node.unwrap().as_mut().next.take(); - if let Some(mut head) = second_part_head { - head.as_mut().prev = None; - } - } - - let second_part = LinkedList { - head: second_part_head, - tail: self.tail, - len: len - at, - marker: PhantomData, - }; - - // Fix the tail ptr of the first part - self.tail = split_node; - self.len = at; - - second_part + unsafe { self.split_off_after_node(split_node, at) } } /// Creates an iterator which uses a closure to determine if an element should be removed. @@ -986,6 +1135,388 @@ impl IterMut<'_, T> { } } +/// A cursor over a `LinkedList`. +/// +/// A `Cursor` is like an iterator, except that it can freely seek back-and-forth. +/// +/// Cursors always rest between two elements in the list, and index in a logically circular way. +/// To accommodate this, there is a "ghost" non-element that yields `None` between the head and +/// tail of the list. +/// +/// When created, cursors start at the front of the list, or the "ghost" non-element if the list is empty. +#[unstable(feature = "linked_list_cursors", issue = "58533")] +pub struct Cursor<'a, T: 'a> { + index: usize, + current: Option>>, + list: &'a LinkedList, +} + +#[unstable(feature = "linked_list_cursors", issue = "58533")] +impl fmt::Debug for Cursor<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_tuple("Cursor").field(&self.list).field(&self.index()).finish() + } +} + +/// A cursor over a `LinkedList` with editing operations. +/// +/// A `Cursor` is like an iterator, except that it can freely seek back-and-forth, and can +/// safely mutate the list during iteration. This is because the lifetime of its yielded +/// references is tied to its own lifetime, instead of just the underlying list. This means +/// cursors cannot yield multiple elements at once. +/// +/// Cursors always rest between two elements in the list, and index in a logically circular way. +/// To accommodate this, there is a "ghost" non-element that yields `None` between the head and +/// tail of the list. +#[unstable(feature = "linked_list_cursors", issue = "58533")] +pub struct CursorMut<'a, T: 'a> { + index: usize, + current: Option>>, + list: &'a mut LinkedList, +} + +#[unstable(feature = "linked_list_cursors", issue = "58533")] +impl fmt::Debug for CursorMut<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_tuple("CursorMut").field(&self.list).field(&self.index()).finish() + } +} + +impl<'a, T> Cursor<'a, T> { + /// Returns the cursor position index within the `LinkedList`. + /// + /// This returns `None` if the cursor is currently pointing to the + /// "ghost" non-element. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn index(&self) -> Option { + let _ = self.current?; + Some(self.index) + } + + /// Moves the cursor to the next element of the `LinkedList`. + /// + /// If the cursor is pointing to the "ghost" non-element then this will move it to + /// the first element of the `LinkedList`. If it is pointing to the last + /// element of the `LinkedList` then this will move it to the "ghost" non-element. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn move_next(&mut self) { + match self.current.take() { + // We had no current element; the cursor was sitting at the start position + // Next element should be the head of the list + None => { + self.current = self.list.head; + self.index = 0; + } + // We had a previous element, so let's go to its next + Some(current) => unsafe { + self.current = current.as_ref().next; + self.index += 1; + }, + } + } + + /// Moves the cursor to the previous element of the `LinkedList`. + /// + /// If the cursor is pointing to the "ghost" non-element then this will move it to + /// the last element of the `LinkedList`. If it is pointing to the first + /// element of the `LinkedList` then this will move it to the "ghost" non-element. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn move_prev(&mut self) { + match self.current.take() { + // No current. We're at the start of the list. Yield None and jump to the end. + None => { + self.current = self.list.tail; + self.index = self.list.len().checked_sub(1).unwrap_or(0); + } + // Have a prev. Yield it and go to the previous element. + Some(current) => unsafe { + self.current = current.as_ref().prev; + self.index = self.index.checked_sub(1).unwrap_or_else(|| self.list.len()); + }, + } + } + + /// Returns a reference to the element that the cursor is currently + /// pointing to. + /// + /// This returns `None` if the cursor is currently pointing to the + /// "ghost" non-element. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn current(&self) -> Option<&'a T> { + unsafe { self.current.map(|current| &(*current.as_ptr()).element) } + } + + /// Returns a reference to the next element. + /// + /// If the cursor is pointing to the "ghost" non-element then this returns + /// the first element of the `LinkedList`. If it is pointing to the last + /// element of the `LinkedList` then this returns `None`. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn peek_next(&self) -> Option<&'a T> { + unsafe { + let next = match self.current { + None => self.list.head, + Some(current) => current.as_ref().next, + }; + next.map(|next| &(*next.as_ptr()).element) + } + } + + /// Returns a reference to the previous element. + /// + /// If the cursor is pointing to the "ghost" non-element then this returns + /// the last element of the `LinkedList`. If it is pointing to the first + /// element of the `LinkedList` then this returns `None`. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn peek_prev(&self) -> Option<&'a T> { + unsafe { + let prev = match self.current { + None => self.list.tail, + Some(current) => current.as_ref().prev, + }; + prev.map(|prev| &(*prev.as_ptr()).element) + } + } +} + +impl<'a, T> CursorMut<'a, T> { + /// Returns the cursor position index within the `LinkedList`. + /// + /// This returns `None` if the cursor is currently pointing to the + /// "ghost" non-element. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn index(&self) -> Option { + let _ = self.current?; + Some(self.index) + } + + /// Moves the cursor to the next element of the `LinkedList`. + /// + /// If the cursor is pointing to the "ghost" non-element then this will move it to + /// the first element of the `LinkedList`. If it is pointing to the last + /// element of the `LinkedList` then this will move it to the "ghost" non-element. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn move_next(&mut self) { + match self.current.take() { + // We had no current element; the cursor was sitting at the start position + // Next element should be the head of the list + None => { + self.current = self.list.head; + self.index = 0; + } + // We had a previous element, so let's go to its next + Some(current) => unsafe { + self.current = current.as_ref().next; + self.index += 1; + }, + } + } + + /// Moves the cursor to the previous element of the `LinkedList`. + /// + /// If the cursor is pointing to the "ghost" non-element then this will move it to + /// the last element of the `LinkedList`. If it is pointing to the first + /// element of the `LinkedList` then this will move it to the "ghost" non-element. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn move_prev(&mut self) { + match self.current.take() { + // No current. We're at the start of the list. Yield None and jump to the end. + None => { + self.current = self.list.tail; + self.index = self.list.len().checked_sub(1).unwrap_or(0); + } + // Have a prev. Yield it and go to the previous element. + Some(current) => unsafe { + self.current = current.as_ref().prev; + self.index = self.index.checked_sub(1).unwrap_or_else(|| self.list.len()); + }, + } + } + + /// Returns a reference to the element that the cursor is currently + /// pointing to. + /// + /// This returns `None` if the cursor is currently pointing to the + /// "ghost" non-element. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn current(&mut self) -> Option<&mut T> { + unsafe { self.current.map(|current| &mut (*current.as_ptr()).element) } + } + + /// Returns a reference to the next element. + /// + /// If the cursor is pointing to the "ghost" non-element then this returns + /// the first element of the `LinkedList`. If it is pointing to the last + /// element of the `LinkedList` then this returns `None`. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn peek_next(&mut self) -> Option<&mut T> { + unsafe { + let next = match self.current { + None => self.list.head, + Some(current) => current.as_ref().next, + }; + next.map(|next| &mut (*next.as_ptr()).element) + } + } + + /// Returns a reference to the previous element. + /// + /// If the cursor is pointing to the "ghost" non-element then this returns + /// the last element of the `LinkedList`. If it is pointing to the first + /// element of the `LinkedList` then this returns `None`. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn peek_prev(&mut self) -> Option<&mut T> { + unsafe { + let prev = match self.current { + None => self.list.tail, + Some(current) => current.as_ref().prev, + }; + prev.map(|prev| &mut (*prev.as_ptr()).element) + } + } + + /// Returns a read-only cursor pointing to the current element. + /// + /// The lifetime of the returned `Cursor` is bound to that of the + /// `CursorMut`, which means it cannot outlive the `CursorMut` and that the + /// `CursorMut` is frozen for the lifetime of the `Cursor`. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn as_cursor<'cm>(&'cm self) -> Cursor<'cm, T> { + Cursor { list: self.list, current: self.current, index: self.index } + } +} + +// Now the list editing operations + +impl<'a, T> CursorMut<'a, T> { + /// Inserts a new element into the `LinkedList` after the current one. + /// + /// If the cursor is pointing at the "ghost" non-element then the new element is + /// inserted at the front of the `LinkedList`. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn insert_after(&mut self, item: T) { + unsafe { + let spliced_node = Box::into_raw_non_null(Box::new(Node::new(item))); + let node_next = match self.current { + None => self.list.head, + Some(node) => node.as_ref().next, + }; + self.list.splice_nodes(self.current, node_next, spliced_node, spliced_node, 1); + if self.current.is_none() { + // The "ghost" non-element's index has changed. + self.index = self.list.len; + } + } + } + + /// Inserts a new element into the `LinkedList` before the current one. + /// + /// If the cursor is pointing at the "ghost" non-element then the new element is + /// inserted at the end of the `LinkedList`. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn insert_before(&mut self, item: T) { + unsafe { + let spliced_node = Box::into_raw_non_null(Box::new(Node::new(item))); + let node_prev = match self.current { + None => self.list.tail, + Some(node) => node.as_ref().prev, + }; + self.list.splice_nodes(node_prev, self.current, spliced_node, spliced_node, 1); + self.index += 1; + } + } + + /// Removes the current element from the `LinkedList`. + /// + /// The element that was removed is returned, and the cursor is + /// moved to point to the next element in the `LinkedList`. + /// + /// If the cursor is currently pointing to the "ghost" non-element then no element + /// is removed and `None` is returned. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn remove_current(&mut self) -> Option { + let unlinked_node = self.current?; + unsafe { + self.current = unlinked_node.as_ref().next; + self.list.unlink_node(unlinked_node); + let unlinked_node = Box::from_raw(unlinked_node.as_ptr()); + Some(unlinked_node.element) + } + } + + /// Inserts the elements from the given `LinkedList` after the current one. + /// + /// If the cursor is pointing at the "ghost" non-element then the new elements are + /// inserted at the start of the `LinkedList`. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn splice_after(&mut self, list: LinkedList) { + unsafe { + let (splice_head, splice_tail, splice_len) = match list.detach_all_nodes() { + Some(parts) => parts, + _ => return, + }; + let node_next = match self.current { + None => self.list.head, + Some(node) => node.as_ref().next, + }; + self.list.splice_nodes(self.current, node_next, splice_head, splice_tail, splice_len); + if self.current.is_none() { + // The "ghost" non-element's index has changed. + self.index = self.list.len; + } + } + } + + /// Inserts the elements from the given `LinkedList` before the current one. + /// + /// If the cursor is pointing at the "ghost" non-element then the new elements are + /// inserted at the end of the `LinkedList`. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn splice_before(&mut self, list: LinkedList) { + unsafe { + let (splice_head, splice_tail, splice_len) = match list.detach_all_nodes() { + Some(parts) => parts, + _ => return, + }; + let node_prev = match self.current { + None => self.list.tail, + Some(node) => node.as_ref().prev, + }; + self.list.splice_nodes(node_prev, self.current, splice_head, splice_tail, splice_len); + self.index += splice_len; + } + } + + /// Splits the list into two after the current element. This will return a + /// new list consisting of everything after the cursor, with the original + /// list retaining everything before. + /// + /// If the cursor is pointing at the "ghost" non-element then the entire contents + /// of the `LinkedList` are moved. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn split_after(&mut self) -> LinkedList { + let split_off_idx = if self.index == self.list.len { 0 } else { self.index + 1 }; + if self.index == self.list.len { + // The "ghost" non-element's index has changed to 0. + self.index = 0; + } + unsafe { self.list.split_off_after_node(self.current, split_off_idx) } + } + + /// Splits the list into two before the current element. This will return a + /// new list consisting of everything before the cursor, with the original + /// list retaining everything after. + /// + /// If the cursor is pointing at the "ghost" non-element then the entire contents + /// of the `LinkedList` are moved. + #[unstable(feature = "linked_list_cursors", issue = "58533")] + pub fn split_before(&mut self) -> LinkedList { + let split_off_idx = self.index; + self.index = 0; + unsafe { self.list.split_off_before_node(self.current, split_off_idx) } + } +} + /// An iterator produced by calling `drain_filter` on LinkedList. #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] pub struct DrainFilter<'a, T: 'a, F: 'a> diff --git a/src/liballoc/collections/linked_list/tests.rs b/src/liballoc/collections/linked_list/tests.rs index 1b1d8eab39bfc..085f734ed916a 100644 --- a/src/liballoc/collections/linked_list/tests.rs +++ b/src/liballoc/collections/linked_list/tests.rs @@ -304,3 +304,155 @@ fn drain_to_empty_test() { assert_eq!(deleted, &[1, 2, 3, 4, 5, 6]); assert_eq!(m.into_iter().collect::>(), &[]); } + +#[test] +fn test_cursor_move_peek() { + let mut m: LinkedList = LinkedList::new(); + m.extend(&[1, 2, 3, 4, 5, 6]); + let mut cursor = m.cursor_front(); + assert_eq!(cursor.current(), Some(&1)); + assert_eq!(cursor.peek_next(), Some(&2)); + assert_eq!(cursor.peek_prev(), None); + assert_eq!(cursor.index(), Some(0)); + cursor.move_prev(); + assert_eq!(cursor.current(), None); + assert_eq!(cursor.peek_next(), Some(&1)); + assert_eq!(cursor.peek_prev(), Some(&6)); + assert_eq!(cursor.index(), None); + cursor.move_next(); + cursor.move_next(); + assert_eq!(cursor.current(), Some(&2)); + assert_eq!(cursor.peek_next(), Some(&3)); + assert_eq!(cursor.peek_prev(), Some(&1)); + assert_eq!(cursor.index(), Some(1)); + + let mut cursor = m.cursor_back(); + assert_eq!(cursor.current(), Some(&6)); + assert_eq!(cursor.peek_next(), None); + assert_eq!(cursor.peek_prev(), Some(&5)); + assert_eq!(cursor.index(), Some(5)); + cursor.move_next(); + assert_eq!(cursor.current(), None); + assert_eq!(cursor.peek_next(), Some(&1)); + assert_eq!(cursor.peek_prev(), Some(&6)); + assert_eq!(cursor.index(), None); + cursor.move_prev(); + cursor.move_prev(); + assert_eq!(cursor.current(), Some(&5)); + assert_eq!(cursor.peek_next(), Some(&6)); + assert_eq!(cursor.peek_prev(), Some(&4)); + assert_eq!(cursor.index(), Some(4)); + + let mut m: LinkedList = LinkedList::new(); + m.extend(&[1, 2, 3, 4, 5, 6]); + let mut cursor = m.cursor_front_mut(); + assert_eq!(cursor.current(), Some(&mut 1)); + assert_eq!(cursor.peek_next(), Some(&mut 2)); + assert_eq!(cursor.peek_prev(), None); + assert_eq!(cursor.index(), Some(0)); + cursor.move_prev(); + assert_eq!(cursor.current(), None); + assert_eq!(cursor.peek_next(), Some(&mut 1)); + assert_eq!(cursor.peek_prev(), Some(&mut 6)); + assert_eq!(cursor.index(), None); + cursor.move_next(); + cursor.move_next(); + assert_eq!(cursor.current(), Some(&mut 2)); + assert_eq!(cursor.peek_next(), Some(&mut 3)); + assert_eq!(cursor.peek_prev(), Some(&mut 1)); + assert_eq!(cursor.index(), Some(1)); + let mut cursor2 = cursor.as_cursor(); + assert_eq!(cursor2.current(), Some(&2)); + assert_eq!(cursor2.index(), Some(1)); + cursor2.move_next(); + assert_eq!(cursor2.current(), Some(&3)); + assert_eq!(cursor2.index(), Some(2)); + assert_eq!(cursor.current(), Some(&mut 2)); + assert_eq!(cursor.index(), Some(1)); + + let mut m: LinkedList = LinkedList::new(); + m.extend(&[1, 2, 3, 4, 5, 6]); + let mut cursor = m.cursor_back_mut(); + assert_eq!(cursor.current(), Some(&mut 6)); + assert_eq!(cursor.peek_next(), None); + assert_eq!(cursor.peek_prev(), Some(&mut 5)); + assert_eq!(cursor.index(), Some(5)); + cursor.move_next(); + assert_eq!(cursor.current(), None); + assert_eq!(cursor.peek_next(), Some(&mut 1)); + assert_eq!(cursor.peek_prev(), Some(&mut 6)); + assert_eq!(cursor.index(), None); + cursor.move_prev(); + cursor.move_prev(); + assert_eq!(cursor.current(), Some(&mut 5)); + assert_eq!(cursor.peek_next(), Some(&mut 6)); + assert_eq!(cursor.peek_prev(), Some(&mut 4)); + assert_eq!(cursor.index(), Some(4)); + let mut cursor2 = cursor.as_cursor(); + assert_eq!(cursor2.current(), Some(&5)); + assert_eq!(cursor2.index(), Some(4)); + cursor2.move_prev(); + assert_eq!(cursor2.current(), Some(&4)); + assert_eq!(cursor2.index(), Some(3)); + assert_eq!(cursor.current(), Some(&mut 5)); + assert_eq!(cursor.index(), Some(4)); +} + +#[test] +fn test_cursor_mut_insert() { + let mut m: LinkedList = LinkedList::new(); + m.extend(&[1, 2, 3, 4, 5, 6]); + let mut cursor = m.cursor_front_mut(); + cursor.insert_before(7); + cursor.insert_after(8); + check_links(&m); + assert_eq!(m.iter().cloned().collect::>(), &[7, 1, 8, 2, 3, 4, 5, 6]); + let mut cursor = m.cursor_front_mut(); + cursor.move_prev(); + cursor.insert_before(9); + cursor.insert_after(10); + check_links(&m); + assert_eq!(m.iter().cloned().collect::>(), &[10, 7, 1, 8, 2, 3, 4, 5, 6, 9]); + let mut cursor = m.cursor_front_mut(); + cursor.move_prev(); + assert_eq!(cursor.remove_current(), None); + cursor.move_next(); + cursor.move_next(); + assert_eq!(cursor.remove_current(), Some(7)); + cursor.move_prev(); + cursor.move_prev(); + cursor.move_prev(); + assert_eq!(cursor.remove_current(), Some(9)); + cursor.move_next(); + assert_eq!(cursor.remove_current(), Some(10)); + check_links(&m); + assert_eq!(m.iter().cloned().collect::>(), &[1, 8, 2, 3, 4, 5, 6]); + let mut cursor = m.cursor_front_mut(); + let mut p: LinkedList = LinkedList::new(); + p.extend(&[100, 101, 102, 103]); + let mut q: LinkedList = LinkedList::new(); + q.extend(&[200, 201, 202, 203]); + cursor.splice_after(p); + cursor.splice_before(q); + check_links(&m); + assert_eq!( + m.iter().cloned().collect::>(), + &[200, 201, 202, 203, 1, 100, 101, 102, 103, 8, 2, 3, 4, 5, 6] + ); + let mut cursor = m.cursor_front_mut(); + cursor.move_prev(); + let tmp = cursor.split_before(); + assert_eq!(m.into_iter().collect::>(), &[]); + m = tmp; + let mut cursor = m.cursor_front_mut(); + cursor.move_next(); + cursor.move_next(); + cursor.move_next(); + cursor.move_next(); + cursor.move_next(); + cursor.move_next(); + let tmp = cursor.split_after(); + assert_eq!(tmp.into_iter().collect::>(), &[102, 103, 8, 2, 3, 4, 5, 6]); + check_links(&m); + assert_eq!(m.iter().cloned().collect::>(), &[200, 201, 202, 203, 1, 100, 101]); +}