Struct CursorMut

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pub struct CursorMut<'a, T: 'a, A: Allocator = Global> { /* private fields */ }

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Expand description

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.

Implementations§

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impl<'a, T, A: Allocator> CursorMut<'a, T, A>

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pub fn index(&self) -> Option<usize>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Returns the cursor position index within the LinkedList.

This returns None if the cursor is currently pointing to the “ghost” non-element.

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pub fn move_next(&mut self)

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn move_prev(&mut self)

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn current(&mut self) -> Option<&mut T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn peek_next(&mut self) -> Option<&mut T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn peek_prev(&mut self) -> Option<&mut T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn as_cursor(&self) -> Cursor<'_, T, A>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn as_list(&self) -> &LinkedList<T, A>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Provides a read-only reference to the cursor’s parent list.

The lifetime of the returned reference 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 reference.

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impl<'a, T> CursorMut<'a, T>

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pub fn splice_after(&mut self, list: LinkedList<T>)

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn splice_before(&mut self, list: LinkedList<T>)

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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impl<'a, T, A: Allocator> CursorMut<'a, T, A>

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pub fn insert_after(&mut self, item: T)

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn insert_before(&mut self, item: T)

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn remove_current(&mut self) -> Option<T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn remove_current_as_list(&mut self) -> Option<LinkedList<T, A>>
where A: Clone,

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn split_after(&mut self) -> LinkedList<T, A>
where A: Clone,

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn split_before(&mut self) -> LinkedList<T, A>
where A: Clone,

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

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.

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pub fn push_front(&mut self, elt: T)

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Appends an element to the front of the cursor’s parent list. The node that the cursor points to is unchanged, even if it is the “ghost” node.

This operation should compute in O(1) time.

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pub fn push_back(&mut self, elt: T)

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Appends an element to the back of the cursor’s parent list. The node that the cursor points to is unchanged, even if it is the “ghost” node.

This operation should compute in O(1) time.

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pub fn pop_front(&mut self) -> Option<T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Removes the first element from the cursor’s parent list and returns it, or None if the list is empty. The element the cursor points to remains unchanged, unless it was pointing to the front element. In that case, it points to the new front element.

This operation should compute in O(1) time.

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pub fn pop_back(&mut self) -> Option<T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Removes the last element from the cursor’s parent list and returns it, or None if the list is empty. The element the cursor points to remains unchanged, unless it was pointing to the back element. In that case, it points to the “ghost” element.

This operation should compute in O(1) time.

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pub fn front(&self) -> Option<&T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Provides a reference to the front element of the cursor’s parent list, or None if the list is empty.

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pub fn front_mut(&mut self) -> Option<&mut T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Provides a mutable reference to the front element of the cursor’s parent list, or None if the list is empty.

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pub fn back(&self) -> Option<&T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Provides a reference to the back element of the cursor’s parent list, or None if the list is empty.

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pub fn back_mut(&mut self) -> Option<&mut T>

🔬This is a nightly-only experimental API. (linked_list_cursors #58533)

Provides a mutable reference to back element of the cursor’s parent list, or None if the list is empty.

§Examples

Building and mutating a list with a cursor, then getting the back element:

#![feature(linked_list_cursors)]
use std::collections::LinkedList;
let mut dl = LinkedList::new();
dl.push_front(3);
dl.push_front(2);
dl.push_front(1);
let mut cursor = dl.cursor_front_mut();
*cursor.current().unwrap() = 99;
*cursor.back_mut().unwrap() = 0;
let mut contents = dl.into_iter();
assert_eq!(contents.next(), Some(99));
assert_eq!(contents.next(), Some(2));
assert_eq!(contents.next(), Some(0));
assert_eq!(contents.next(), None);