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implement deletion in art tree

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This commit is contained in:
Heikki Linnakangas
2025-05-04 23:29:01 +03:00
parent 42df3e5453
commit 884e028a4a
8 changed files with 322 additions and 94 deletions
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85
libs/neonart/src/algorithm/node_ptr.rs
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@@ -404,6 +404,19 @@ impl<V: Value> NodePtr<V> {
}
}
pub(crate) fn delete_value(&mut self, key_byte: u8) {
match self.variant_mut() {
NodeVariantMut::Internal4(_)
| NodeVariantMut::Internal16(_)
| NodeVariantMut::Internal48(_)
| NodeVariantMut::Internal256(_) => panic!("delete_value called on internal node"),
NodeVariantMut::Leaf4(n) => n.delete_value(key_byte),
NodeVariantMut::Leaf16(n) => n.delete_value(key_byte),
NodeVariantMut::Leaf48(n) => n.delete_value(key_byte),
NodeVariantMut::Leaf256(n) => n.delete_value(key_byte),
}
}
pub(crate) fn deallocate(self, allocator: &impl ArtAllocator<V>) {
match self.variant() {
NodeVariant::Internal4(_) => allocator.dealloc_node_internal4(self.ptr.cast()),
@@ -766,7 +779,7 @@ impl<V: Value> NodeLeaf4<V> {
}
fn insert_value(&mut self, key_byte: u8, value: V) {
assert!(self.num_values < 16);
assert!(self.num_values < 4);
let idx = self.num_values as usize;
self.child_keys[idx] = key_byte;
@@ -797,6 +810,23 @@ impl<V: Value> NodeLeaf4<V> {
unsafe { ptr.write(init) };
ptr.into()
}
fn delete_value(&mut self, key_byte: u8) {
assert!(self.num_values <= 4);
for i in 0..self.num_values as usize {
if self.child_keys[i] == key_byte {
assert!(self.child_values[i].is_some());
if i < self.num_values as usize - 1 {
self.child_keys[i] = self.child_keys[self.num_values as usize - 1];
self.child_values[i] = std::mem::replace(&mut self.child_values[self.num_values as usize - 1], None);
}
self.num_values -= 1;
return;
}
}
panic!("key to delete not found in leaf4 node");
}
}
impl<V: Value> NodeLeaf16<V> {
@@ -859,6 +889,23 @@ impl<V: Value> NodeLeaf16<V> {
unsafe { ptr.write(init) };
ptr.into()
}
fn delete_value(&mut self, key_byte: u8) {
assert!(self.num_values <= 16);
for i in 0..self.num_values as usize {
if self.child_keys[i as usize] == key_byte {
assert!(self.child_values[i as usize].is_some());
if i < self.num_values as usize - 1 {
self.child_keys[i] = self.child_keys[self.num_values as usize - 1];
self.child_values[i] = std::mem::replace(&mut self.child_values[self.num_values as usize - 1], None);
}
self.num_values -= 1;
return;
}
}
panic!("key to delete not found in leaf16 node");
}
}
impl<V: Value> NodeLeaf48<V> {
@@ -921,6 +968,34 @@ impl<V: Value> NodeLeaf48<V> {
unsafe { ptr.write(init) };
ptr.into()
}
fn delete_value(&mut self, key_byte: u8) {
assert!(self.num_values <= 48);
let idx = self.child_indexes[key_byte as usize];
if idx == INVALID_CHILD_INDEX {
panic!("key to delete not found in leaf48 node");
}
self.child_indexes[key_byte as usize] = INVALID_CHILD_INDEX;
self.num_values -= 1;
if idx < self.num_values {
// Move all existing values with higher indexes down one position
for i in idx as usize ..self.num_values as usize {
self.child_values[i] = std::mem::replace(&mut self.child_values[i + 1], None);
}
// Update all higher indexes
for i in 0..256 {
if self.child_indexes[i] != INVALID_CHILD_INDEX {
if self.child_indexes[i] > idx {
self.child_indexes[i] -= 1;
}
assert!(self.child_indexes[i] < self.num_values);
}
}
}
}
}
impl<V: Value> NodeLeaf256<V> {
@@ -952,6 +1027,14 @@ impl<V: Value> NodeLeaf256<V> {
self.child_values[key_byte as usize] = Some(value);
self.num_values += 1;
}
fn delete_value(&mut self, key_byte: u8) {
if self.child_values[key_byte as usize].is_none() {
panic!("key to delete not found in leaf256 node");
}
self.child_values[key_byte as usize] = None;
self.num_values -= 1;
}
}
impl<V: Value> NodeInternal256<V> {