From 1593e2b7df05da71162b9ad0e3f12d577aec3131 Mon Sep 17 00:00:00 2001
From: "main()" <main@ehvag.de>
Date: Mon, 4 May 2020 15:53:02 +0200
Subject: [PATCH 1/2] Add remove_current_as_list to LinkedList's CursorMut
The `remove_current` method only returns the inner `T` and deallocates the list node. This is unnecessary for move operations, where the element is going to be linked back into this (or even a different) `LinkedList`. The `remove_current_as_list` method avoids this by returning the unlinked list node as a new single-element `LinkedList` structure .
---
src/liballoc/collections/linked_list.rs | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/src/liballoc/collections/linked_list.rs b/src/liballoc/collections/linked_list.rs
index bfa4045787f5b..952e5317840a1 100644
--- a/src/liballoc/collections/linked_list.rs
+++ b/src/liballoc/collections/linked_list.rs
@@ -1496,6 +1496,31 @@ impl<'a, T> CursorMut<'a, T> {
}
}
+ /// Removes the current element from the `LinkedList` without deallocating the list node.
+ ///
+ /// The node that was removed is returned as a new `LinkedList` containing only this node.
+ /// The cursor is moved to point to the next element in the current `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_as_list(&mut self) -> Option<LinkedList<T>> {
+ let unlinked_node = self.current?;
+ unsafe {
+ self.current = unlinked_node.as_ref().next;
+ self.list.unlink_node(unlinked_node);
+
+ unlinked_node.as_mut().prev = None;
+ unlinked_node.as_mut().next = None;
+ Some(LinkedList {
+ head: Some(unlinked_node),
+ tail: Some(unlinked_node),
+ len: 1,
+ marker: PhantomData,
+ })
+ }
+ }
+
/// 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
From c5cdf7fe920c8cb3b60f5a6e257f6cdfb51102d3 Mon Sep 17 00:00:00 2001
From: "main()" <main@ehvag.de>
Date: Mon, 4 May 2020 16:10:59 +0200
Subject: [PATCH 2/2] whoops
---
src/liballoc/collections/linked_list.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/liballoc/collections/linked_list.rs b/src/liballoc/collections/linked_list.rs
index 952e5317840a1..cc0f07b822741 100644
--- a/src/liballoc/collections/linked_list.rs
+++ b/src/liballoc/collections/linked_list.rs
@@ -1505,7 +1505,7 @@ impl<'a, T> CursorMut<'a, T> {
/// is removed and `None` is returned.
#[unstable(feature = "linked_list_cursors", issue = "58533")]
pub fn remove_current_as_list(&mut self) -> Option<LinkedList<T>> {
- let unlinked_node = self.current?;
+ let mut unlinked_node = self.current?;
unsafe {
self.current = unlinked_node.as_ref().next;
self.list.unlink_node(unlinked_node);