BTreeMap: various tweaks
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3965524570
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55fa8afe94
1 changed files with 50 additions and 61 deletions
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@ -47,8 +47,7 @@ const KV_IDX_CENTER: usize = B - 1;
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const EDGE_IDX_LEFT_OF_CENTER: usize = B - 1;
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const EDGE_IDX_RIGHT_OF_CENTER: usize = B;
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/// The underlying representation of leaf nodes.
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#[repr(C)]
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/// The underlying representation of leaf nodes and part of the representation of internal nodes.
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struct LeafNode<K, V> {
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/// We want to be covariant in `K` and `V`.
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parent: Option<NonNull<InternalNode<K, V>>>,
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@ -59,9 +58,6 @@ struct LeafNode<K, V> {
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parent_idx: MaybeUninit<u16>,
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/// The number of keys and values this node stores.
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///
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/// This next to `parent_idx` to encourage the compiler to join `len` and
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/// `parent_idx` into the same 32-bit word, reducing space overhead.
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len: u16,
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/// The arrays storing the actual data of the node. Only the first `len` elements of each
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@ -92,7 +88,9 @@ impl<K, V> LeafNode<K, V> {
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/// node, allowing code to act on leaf and internal nodes generically without having to even check
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/// which of the two a pointer is pointing at. This property is enabled by the use of `repr(C)`.
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#[repr(C)]
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// gdb_providers.py uses this type name for introspection.
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struct InternalNode<K, V> {
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// gdb_providers.py uses this field name for introspection.
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data: LeafNode<K, V>,
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/// The pointers to the children of this node. `len + 1` of these are considered
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@ -183,9 +181,9 @@ impl<K, V> Root<K, V> {
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NodeRef { height: self.height, node: self.node.as_ptr(), _marker: PhantomData }
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}
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/// Adds a new internal node with a single edge, pointing to the previous root, and make that
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/// new node the root. This increases the height by 1 and is the opposite of
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/// `pop_internal_level`.
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/// Adds a new internal node with a single edge pointing to the previous root node,
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/// make that new node the root node, and return it. This increases the height by 1
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/// and is the opposite of `pop_internal_level`.
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pub fn push_internal_level(&mut self) -> NodeRef<marker::Mut<'_>, K, V, marker::Internal> {
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let mut new_node = Box::new(unsafe { InternalNode::new() });
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new_node.edges[0].write(unsafe { BoxedNode::from_ptr(self.node.as_ptr()) });
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@ -322,7 +320,7 @@ impl<BorrowType, K, V, Type> NodeRef<BorrowType, K, V, Type> {
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NodeRef { height: self.height, node: self.node, _marker: PhantomData }
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}
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/// Exposes the leaf "portion" of any leaf or internal node.
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/// Exposes the leaf portion of any leaf or internal node.
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/// If the node is a leaf, this function simply opens up its data.
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/// If the node is an internal node, so not a leaf, it does have all the data a leaf has
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/// (header, keys and values), and this function exposes that.
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@ -472,7 +470,7 @@ impl<'a, K, V, Type> NodeRef<marker::Mut<'a>, K, V, Type> {
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NodeRef { height: self.height, node: self.node, _marker: PhantomData }
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}
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/// Exposes the leaf "portion" of any leaf or internal node for writing.
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/// Exposes the leaf portion of any leaf or internal node for writing.
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/// If the node is a leaf, this function simply opens up its data.
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/// If the node is an internal node, so not a leaf, it does have all the data a leaf has
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/// (header, keys and values), and this function exposes that.
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@ -498,18 +496,38 @@ impl<'a, K, V, Type> NodeRef<marker::Mut<'a>, K, V, Type> {
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unsafe { self.reborrow_mut().into_val_mut_at(idx) }
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}
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fn keys_mut(&mut self) -> &mut [K] {
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fn keys_mut(&mut self) -> &mut [K]
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where
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K: 'a,
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V: 'a,
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{
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// SAFETY: the caller will not be able to call further methods on self
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// until the key slice reference is dropped, as we have unique access
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// for the lifetime of the borrow.
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unsafe { self.reborrow_mut().into_key_slice_mut() }
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// SAFETY: The keys of a node must always be initialized up to length.
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unsafe {
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slice::from_raw_parts_mut(
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MaybeUninit::slice_as_mut_ptr(&mut self.as_leaf_mut().keys),
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self.len(),
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)
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}
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}
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fn vals_mut(&mut self) -> &mut [V] {
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fn vals_mut(&mut self) -> &mut [V]
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where
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K: 'a,
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V: 'a,
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{
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// SAFETY: the caller will not be able to call further methods on self
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// until the value slice reference is dropped, as we have unique access
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// for the lifetime of the borrow.
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unsafe { self.reborrow_mut().into_val_slice_mut() }
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// SAFETY: The values of a node must always be initialized up to length.
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unsafe {
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slice::from_raw_parts_mut(
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MaybeUninit::slice_as_mut_ptr(&mut self.as_leaf_mut().vals),
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self.len(),
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)
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}
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}
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}
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@ -539,26 +557,6 @@ impl<'a, K: 'a, V: 'a, Type> NodeRef<marker::Immut<'a>, K, V, Type> {
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}
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impl<'a, K: 'a, V: 'a, Type> NodeRef<marker::Mut<'a>, K, V, Type> {
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fn into_key_slice_mut(mut self) -> &'a mut [K] {
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// SAFETY: The keys of a node must always be initialized up to length.
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unsafe {
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slice::from_raw_parts_mut(
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MaybeUninit::slice_as_mut_ptr(&mut self.as_leaf_mut().keys),
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self.len(),
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)
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}
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}
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fn into_val_slice_mut(mut self) -> &'a mut [V] {
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// SAFETY: The values of a node must always be initialized up to length.
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unsafe {
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slice::from_raw_parts_mut(
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MaybeUninit::slice_as_mut_ptr(&mut self.as_leaf_mut().vals),
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self.len(),
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)
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}
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}
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/// # Safety
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/// The node has more than `idx` initialized elements.
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unsafe fn into_key_mut_at(mut self, idx: usize) -> &'a mut K {
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@ -610,8 +608,8 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::Leaf> {
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}
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/// Adds a key/value pair to the beginning of the node.
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pub fn push_front(&mut self, key: K, val: V) {
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assert!(self.len() < CAPACITY);
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fn push_front(&mut self, key: K, val: V) {
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debug_assert!(self.len() < CAPACITY);
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unsafe {
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slice_insert(self.keys_mut(), 0, key);
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@ -683,10 +681,9 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::Internal> {
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impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal> {
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/// Removes a key/value pair from the end of this node and returns the pair.
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/// If this is an internal node, also removes the edge that was to the right
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/// of that pair and returns the orphaned node that this edge owned with its
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/// parent erased.
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pub fn pop(&mut self) -> (K, V, Option<Root<K, V>>) {
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assert!(self.len() > 0);
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/// of that pair and returns the orphaned node that this edge owned.
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fn pop(&mut self) -> (K, V, Option<Root<K, V>>) {
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debug_assert!(self.len() > 0);
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let idx = self.len() - 1;
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@ -708,10 +705,11 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal> {
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}
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}
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/// Removes a key/value pair from the beginning of this node. If this is an internal node,
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/// also removes the edge that was to the left of that pair.
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pub fn pop_front(&mut self) -> (K, V, Option<Root<K, V>>) {
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assert!(self.len() > 0);
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/// Removes a key/value pair from the beginning of this node and returns the pair.
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/// If this is an internal node, also removes the edge that was to the left
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/// of that pair and returns the orphaned node that this edge owned.
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fn pop_front(&mut self) -> (K, V, Option<Root<K, V>>) {
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debug_assert!(self.len() > 0);
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let old_len = self.len();
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@ -913,7 +911,6 @@ impl<'a, K: 'a, V: 'a, NodeType> Handle<NodeRef<marker::Mut<'a>, K, V, NodeType>
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/// this edge. This method assumes that there is enough space in the node for the new
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/// pair to fit.
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fn leafy_insert_fit(&mut self, key: K, val: V) {
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// Necessary for correctness, but in a private module
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debug_assert!(self.node.len() < CAPACITY);
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unsafe {
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@ -951,18 +948,18 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, mark
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let (middle_kv_idx, insertion) = splitpoint(self.idx);
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let middle = unsafe { Handle::new_kv(self.node, middle_kv_idx) };
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let (mut left, k, v, mut right) = middle.split();
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let val_ptr = match insertion {
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let mut insertion_edge = match insertion {
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InsertionPlace::Left(insert_idx) => unsafe {
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Handle::new_edge(left.reborrow_mut(), insert_idx).insert_fit(key, val)
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Handle::new_edge(left.reborrow_mut(), insert_idx)
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},
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InsertionPlace::Right(insert_idx) => unsafe {
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Handle::new_edge(
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right.node_as_mut().cast_unchecked::<marker::Leaf>(),
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insert_idx,
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)
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.insert_fit(key, val)
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},
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};
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let val_ptr = insertion_edge.insert_fit(key, val);
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(InsertResult::Split(SplitResult { left: left.forget_type(), k, v, right }), val_ptr)
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}
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}
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@ -985,8 +982,6 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>,
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/// between this edge and the key/value pair to the right of this edge. This method assumes
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/// that there is enough space in the node for the new pair to fit.
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fn insert_fit(&mut self, key: K, val: V, edge: Root<K, V>) {
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// Necessary for correctness, but in an internal module
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debug_assert!(self.node.len() < CAPACITY);
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debug_assert!(edge.height == self.node.height - 1);
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unsafe {
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@ -1136,12 +1131,12 @@ impl<'a, K: 'a, V: 'a, NodeType> Handle<NodeRef<marker::Mut<'a>, K, V, NodeType>
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ptr::copy_nonoverlapping(
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self.node.key_at(self.idx + 1),
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new_node.keys.as_mut_ptr() as *mut K,
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MaybeUninit::slice_as_mut_ptr(&mut new_node.keys),
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new_len,
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);
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ptr::copy_nonoverlapping(
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self.node.val_at(self.idx + 1),
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new_node.vals.as_mut_ptr() as *mut V,
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MaybeUninit::slice_as_mut_ptr(&mut new_node.vals),
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new_len,
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);
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@ -1376,9 +1371,7 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>,
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move_edges(left, new_left_len + 1, right, 0, count);
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}
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(ForceResult::Leaf(_), ForceResult::Leaf(_)) => {}
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_ => {
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unreachable!();
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}
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_ => unreachable!(),
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}
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}
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}
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@ -1433,9 +1426,7 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>,
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right.correct_childrens_parent_links(0..=new_right_len);
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}
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(ForceResult::Leaf(_), ForceResult::Leaf(_)) => {}
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_ => {
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unreachable!();
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}
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_ => unreachable!(),
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}
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}
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}
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@ -1568,9 +1559,7 @@ impl<'a, K, V> Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>, ma
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move_edges(left, left_new_len + 1, right, 1, right_new_len);
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}
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(ForceResult::Leaf(_), ForceResult::Leaf(_)) => {}
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_ => {
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unreachable!();
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}
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_ => unreachable!(),
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}
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}
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}
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