Struct CursorMut

pub struct CursorMut<'a, K, V, A = Global>
where
    K: 'a,
    V: 'a,
{ /* private fields */ }

A cursor over a BTreeMap with editing operations.

A Cursor is like an iterator, except that it can freely seek back-and-forth, and can safely mutate the tree during iteration. This is because the lifetime of its yielded references is tied to its own lifetime, instead of just the underlying tree. This means cursors cannot yield multiple elements at once.

Cursors always point to an element in the tree, and index in a logically circular way. To accommodate this, there is a “ghost” non-element that yields None between the last and first elements of the tree.

A Cursor is created with the BTreeMap::lower_bound_mut and BTreeMap::upper_bound_mut methods.

Implementations

impl<'a, K, V, A> CursorMut<'a, K, V, A>

pub fn key(&self) -> Option<&K>

Returns a reference to the key of the element that the cursor is currently pointing to.

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

pub fn value(&self) -> Option<&V>

Returns a reference to the value of the element that the cursor is currently pointing to.

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

pub fn key_value(&self) -> Option<(&K, &V)>

Returns a reference to the key and value of the element that the cursor is currently pointing to.

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

pub fn value_mut(&mut self) -> Option<&mut V>

Returns a mutable reference to the value of the element that the cursor is currently pointing to.

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

pub fn key_value_mut(&mut self) -> Option<(&K, &mut V)>

Returns a reference to the key and mutable reference to the value of the element that the cursor is currently pointing to.

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

Trait Implementations

impl<K, V, A> Debug for CursorMut<'_, K, V, A>

where K: Debug, V: Debug,

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

Formats the value using the given formatter.