Struct alloc::collections::btree_map::Cursor

pub struct Cursor<'a, K: 'a, V: 'a> {
    current: Option<Handle<NodeRef<Immut<'a>, K, V, LeafOrInternal>, KV>>,
    root: Option<&'a NodeRef<Owned, K, V, LeafOrInternal>>,
}

🔬This is a nightly-only experimental API. (btree_cursors #107540)

A cursor over a BTreeMap.

A Cursor is like an iterator, except that it can freely seek back-and-forth.

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 and BTreeMap::upper_bound methods.

Fields

current: Option<Handle<NodeRef<Immut<'a>, K, V, LeafOrInternal>, KV>>

🔬This is a nightly-only experimental API. (btree_cursors #107540)

root: Option<&'a NodeRef<Owned, K, V, LeafOrInternal>>

🔬This is a nightly-only experimental API. (btree_cursors #107540)

Implementations

impl<'a, K, V> Cursor<'a, K, V>

pub fn move_next(&mut self)

🔬This is a nightly-only experimental API. (btree_cursors #107540)

Moves the cursor to the next element of the BTreeMap.

If the cursor is pointing to the “ghost” non-element then this will move it to the first element of the BTreeMap. If it is pointing to the last element of the BTreeMap then this will move it to the “ghost” non-element.

pub fn move_prev(&mut self)

🔬This is a nightly-only experimental API. (btree_cursors #107540)

Moves the cursor to the previous element of the BTreeMap.

If the cursor is pointing to the “ghost” non-element then this will move it to the last element of the BTreeMap. If it is pointing to the first element of the BTreeMap then this will move it to the “ghost” non-element.

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

🔬This is a nightly-only experimental API. (btree_cursors #107540)

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<&'a V>

🔬This is a nightly-only experimental API. (btree_cursors #107540)

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<(&'a K, &'a V)>

🔬This is a nightly-only experimental API. (btree_cursors #107540)

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 peek_next(&self) -> Option<(&'a K, &'a V)>

🔬This is a nightly-only experimental API. (btree_cursors #107540)

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 BTreeMap. If it is pointing to the last element of the BTreeMap then this returns None.

pub fn peek_prev(&self) -> Option<(&'a K, &'a V)>

🔬This is a nightly-only experimental API. (btree_cursors #107540)

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 BTreeMap. If it is pointing to the first element of the BTreeMap then this returns None.

Trait Implementations

impl<K, V> Clone for Cursor<'_, K, V>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<K: Debug, V: Debug> Debug for Cursor<'_, K, V>

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

Formats the value using the given formatter.