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use super::map::MIN_LEN;
use super::node::{marker, ForceResult::*, Handle, LeftOrRight::*, NodeRef};
use super::unwrap_unchecked;
impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>, marker::KV> {
pub fn remove_kv_tracking<F: FnOnce()>(
self,
handle_emptied_internal_root: F,
) -> ((K, V), Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>) {
match self.force() {
Leaf(node) => node.remove_leaf_kv(handle_emptied_internal_root),
Internal(node) => node.remove_internal_kv(handle_emptied_internal_root),
}
}
}
impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::KV> {
fn remove_leaf_kv<F: FnOnce()>(
self,
handle_emptied_internal_root: F,
) -> ((K, V), Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>) {
let (old_kv, mut pos) = self.remove();
let len = pos.reborrow().into_node().len();
if len < MIN_LEN {
let idx = pos.idx();
let new_pos = match pos.into_node().forget_type().choose_parent_kv() {
Ok(Left(left_parent_kv)) => {
debug_assert!(left_parent_kv.right_child_len() == MIN_LEN - 1);
if left_parent_kv.can_merge() {
left_parent_kv.merge(Some(Right(idx)))
} else {
debug_assert!(left_parent_kv.left_child_len() > MIN_LEN);
left_parent_kv.steal_left(idx)
}
}
Ok(Right(right_parent_kv)) => {
debug_assert!(right_parent_kv.left_child_len() == MIN_LEN - 1);
if right_parent_kv.can_merge() {
right_parent_kv.merge(Some(Left(idx)))
} else {
debug_assert!(right_parent_kv.right_child_len() > MIN_LEN);
right_parent_kv.steal_right(idx)
}
}
Err(pos) => unsafe { Handle::new_edge(pos, idx) },
};
pos = unsafe { new_pos.cast_to_leaf_unchecked() };
if let Ok(parent) = unsafe { pos.reborrow_mut() }.into_node().ascend() {
parent.into_node().handle_shrunk_node_recursively(handle_emptied_internal_root);
}
}
(old_kv, pos)
}
}
impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>, marker::KV> {
fn remove_internal_kv<F: FnOnce()>(
self,
handle_emptied_internal_root: F,
) -> ((K, V), Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>) {
let left_leaf_kv = self.left_edge().descend().last_leaf_edge().left_kv();
let left_leaf_kv = unsafe { unwrap_unchecked(left_leaf_kv.ok()) };
let (left_kv, left_hole) = left_leaf_kv.remove_leaf_kv(handle_emptied_internal_root);
let mut internal = unsafe { unwrap_unchecked(left_hole.next_kv().ok()) };
let old_kv = internal.replace_kv(left_kv.0, left_kv.1);
let pos = internal.next_leaf_edge();
(old_kv, pos)
}
}
impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::Internal> {
fn handle_shrunk_node_recursively<F: FnOnce()>(mut self, handle_emptied_internal_root: F) {
loop {
self = match self.len() {
0 => {
debug_assert!(self.ascend().is_err());
handle_emptied_internal_root();
return;
}
1..MIN_LEN => {
if let Some(parent) = self.handle_underfull_node_locally() {
parent
} else {
return;
}
}
_ => return,
}
}
}
fn handle_underfull_node_locally(
self,
) -> Option<NodeRef<marker::Mut<'a>, K, V, marker::Internal>> {
match self.forget_type().choose_parent_kv() {
Ok(Left(left_parent_kv)) => {
debug_assert_eq!(left_parent_kv.right_child_len(), MIN_LEN - 1);
if left_parent_kv.can_merge() {
let pos = left_parent_kv.merge(None);
let parent_edge = unsafe { unwrap_unchecked(pos.into_node().ascend().ok()) };
Some(parent_edge.into_node())
} else {
debug_assert!(left_parent_kv.left_child_len() > MIN_LEN);
left_parent_kv.steal_left(0);
None
}
}
Ok(Right(right_parent_kv)) => {
debug_assert_eq!(right_parent_kv.left_child_len(), MIN_LEN - 1);
if right_parent_kv.can_merge() {
let pos = right_parent_kv.merge(None);
let parent_edge = unsafe { unwrap_unchecked(pos.into_node().ascend().ok()) };
Some(parent_edge.into_node())
} else {
debug_assert!(right_parent_kv.right_child_len() > MIN_LEN);
right_parent_kv.steal_right(0);
None
}
}
Err(_) => None,
}
}
}