# 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);

## Trait Implementations§

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### impl<T: Debug, A: Allocator> Debug for CursorMut<'_, T, A>

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl<T: Send, A: Allocator + Send> Send for CursorMut<'_, T, A>

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### impl<T: Sync, A: Allocator + Sync> Sync for CursorMut<'_, T, A>

## Auto Trait Implementations§

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### impl<'a, T, A> Freeze for CursorMut<'a, T, A>

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### impl<'a, T, A> RefUnwindSafe for CursorMut<'a, T, A>
where A: RefUnwindSafe, T: RefUnwindSafe,

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### impl<'a, T, A> Unpin for CursorMut<'a, T, A>

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### impl<'a, T, A = Global> !UnwindSafe for CursorMut<'a, T, A>

## Blanket Implementations§

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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.