Struct switchboard_solana::prelude::borsh::maybestd::collections::btree_map::CursorMutKey
source · pub struct CursorMutKey<'a, K, V, A = Global>where
K: 'a,
V: 'a,{ /* private fields */ }btree_cursors)Expand description
A cursor over a BTreeMap with editing operations, and which allows
mutating the key of elements.
A Cursor is like an iterator, except that it can freely seek back-and-forth, and can
safely mutate the map during iteration. This is because the lifetime of its yielded
references is tied to its own lifetime, instead of just the underlying map. This means
cursors cannot yield multiple elements at once.
Cursors always point to a gap between two elements in the map, and can operate on the two immediately adjacent elements.
A CursorMutKey is created from a CursorMut with the
CursorMut::with_mutable_key method.
§Safety
Since this cursor allows mutating keys, you must ensure that the BTreeMap
invariants are maintained. Specifically:
- The key of the newly inserted element must be unique in the tree.
- All keys in the tree must remain in sorted order.
Implementations§
source§impl<'a, K, V, A> CursorMutKey<'a, K, V, A>
impl<'a, K, V, A> CursorMutKey<'a, K, V, A>
sourcepub fn next(&mut self) -> Option<(&mut K, &mut V)>
🔬This is a nightly-only experimental API. (btree_cursors)
pub fn next(&mut self) -> Option<(&mut K, &mut V)>
btree_cursors)Advances the cursor to the next gap, returning the key and value of the element that it moved over.
If the cursor is already at the end of the map then None is returned
and the cursor is not moved.
sourcepub fn prev(&mut self) -> Option<(&mut K, &mut V)>
🔬This is a nightly-only experimental API. (btree_cursors)
pub fn prev(&mut self) -> Option<(&mut K, &mut V)>
btree_cursors)Advances the cursor to the previous gap, returning the key and value of the element that it moved over.
If the cursor is already at the start of the map then None is returned
and the cursor is not moved.
sourcepub fn peek_next(&mut self) -> Option<(&mut K, &mut V)>
🔬This is a nightly-only experimental API. (btree_cursors)
pub fn peek_next(&mut self) -> Option<(&mut K, &mut V)>
btree_cursors)Returns a reference to the the key and value of the next element without moving the cursor.
If the cursor is at the end of the map then None is returned
sourcepub fn peek_prev(&mut self) -> Option<(&mut K, &mut V)>
🔬This is a nightly-only experimental API. (btree_cursors)
pub fn peek_prev(&mut self) -> Option<(&mut K, &mut V)>
btree_cursors)Returns a reference to the the key and value of the previous element without moving the cursor.
If the cursor is at the start of the map then None is returned.
sourcepub fn as_cursor(&self) -> Cursor<'_, K, V>
🔬This is a nightly-only experimental API. (btree_cursors)
pub fn as_cursor(&self) -> Cursor<'_, K, V>
btree_cursors)Returns a read-only cursor pointing to the same location as the
CursorMutKey.
The lifetime of the returned Cursor is bound to that of the
CursorMutKey, which means it cannot outlive the CursorMutKey and that the
CursorMutKey is frozen for the lifetime of the Cursor.
source§impl<'a, K, V, A> CursorMutKey<'a, K, V, A>
impl<'a, K, V, A> CursorMutKey<'a, K, V, A>
sourcepub unsafe fn insert_after_unchecked(&mut self, key: K, value: V)
🔬This is a nightly-only experimental API. (btree_cursors)
pub unsafe fn insert_after_unchecked(&mut self, key: K, value: V)
btree_cursors)Inserts a new element into the BTreeMap in the gap that the
CursorMutKey is currently pointing to.
After the insertion the cursor will be pointing at the gap before the newly inserted element.
§Safety
You must ensure that the BTreeMap invariants are maintained.
Specifically:
- The key of the newly inserted element must be unique in the tree.
- All keys in the tree must remain in sorted order.
sourcepub unsafe fn insert_before_unchecked(&mut self, key: K, value: V)
🔬This is a nightly-only experimental API. (btree_cursors)
pub unsafe fn insert_before_unchecked(&mut self, key: K, value: V)
btree_cursors)Inserts a new element into the BTreeMap in the gap that the
CursorMutKey is currently pointing to.
After the insertion the cursor will be pointing at the gap after the newly inserted element.
§Safety
You must ensure that the BTreeMap invariants are maintained.
Specifically:
- The key of the newly inserted element must be unique in the tree.
- All keys in the tree must remain in sorted order.
sourcepub fn insert_after(
&mut self,
key: K,
value: V
) -> Result<(), UnorderedKeyError>
🔬This is a nightly-only experimental API. (btree_cursors)
pub fn insert_after( &mut self, key: K, value: V ) -> Result<(), UnorderedKeyError>
btree_cursors)Inserts a new element into the BTreeMap in the gap that the
CursorMutKey is currently pointing to.
After the insertion the cursor will be pointing at the gap before the newly inserted element.
§Panics
This function panics if:
- the given key compares less than or equal to the current element (if any).
- the given key compares greater than or equal to the next element (if any).
sourcepub fn insert_before(
&mut self,
key: K,
value: V
) -> Result<(), UnorderedKeyError>
🔬This is a nightly-only experimental API. (btree_cursors)
pub fn insert_before( &mut self, key: K, value: V ) -> Result<(), UnorderedKeyError>
btree_cursors)Inserts a new element into the BTreeMap in the gap that the
CursorMutKey is currently pointing to.
After the insertion the cursor will be pointing at the gap after the newly inserted element.
§Panics
This function panics if:
- the given key compares greater than or equal to the current element (if any).
- the given key compares less than or equal to the previous element (if any).
sourcepub fn remove_next(&mut self) -> Option<(K, V)>
🔬This is a nightly-only experimental API. (btree_cursors)
pub fn remove_next(&mut self) -> Option<(K, V)>
btree_cursors)Removes the next element from the BTreeMap.
The element that was removed is returned. The cursor position is unchanged (before the removed element).
sourcepub fn remove_prev(&mut self) -> Option<(K, V)>
🔬This is a nightly-only experimental API. (btree_cursors)
pub fn remove_prev(&mut self) -> Option<(K, V)>
btree_cursors)Removes the precending element from the BTreeMap.
The element that was removed is returned. The cursor position is unchanged (after the removed element).