531 lines
17 KiB
Rust
531 lines
17 KiB
Rust
use std::{fmt, iter::FromIterator, ops::AddAssign, sync::Arc};
|
|
|
|
use arrayvec::ArrayVec;
|
|
pub use cursor::Cursor;
|
|
pub use cursor::FilterCursor;
|
|
|
|
mod cursor;
|
|
|
|
#[cfg(feature = "test-util")]
|
|
const TREE_BASE: usize = 2;
|
|
#[cfg(not(feature = "test-util"))]
|
|
const TREE_BASE: usize = 6;
|
|
|
|
pub trait Item: Clone + fmt::Debug {
|
|
type Summary: for<'a> AddAssign<&'a Self::Summary> + Default + Clone + fmt::Debug;
|
|
|
|
fn summary(&self) -> Self::Summary;
|
|
}
|
|
|
|
pub trait KeyedItem: Item {
|
|
type Key: for<'a> Dimension<'a, Self::Summary> + Ord;
|
|
|
|
fn key(&self) -> Self::Key;
|
|
}
|
|
|
|
pub trait Dimension<'a, Summary: Default>: 'a + Clone + fmt::Debug + Default {
|
|
fn add_summary(&mut self, summary: &'a Summary);
|
|
}
|
|
|
|
impl<'a, T: Default> Dimension<'a, T> for () {
|
|
fn add_summary(&mut self, _: &'a T) {}
|
|
}
|
|
|
|
#[derive(Copy, Clone, Eq, PartialEq)]
|
|
pub enum SeekBias {
|
|
Left,
|
|
Right,
|
|
}
|
|
|
|
#[derive(Debug, Clone)]
|
|
pub struct SumTree<T: Item>(Arc<Node<T>>);
|
|
|
|
impl<T: Item> Default for SumTree<T> {
|
|
fn default() -> Self {
|
|
Self::new()
|
|
}
|
|
}
|
|
|
|
impl<T: Item> SumTree<T> {
|
|
pub fn new() -> Self {
|
|
SumTree(Arc::new(Node::Leaf {
|
|
summary: T::Summary::default(),
|
|
items: ArrayVec::new(),
|
|
item_summaries: ArrayVec::new(),
|
|
}))
|
|
}
|
|
|
|
pub fn from_item(item: T) -> Self {
|
|
let mut tree = Self::new();
|
|
tree.push(item);
|
|
tree
|
|
}
|
|
|
|
#[cfg(feature = "test-util")]
|
|
pub fn items(&self) -> Vec<T> {
|
|
let mut cursor = self.cursor::<(), ()>();
|
|
cursor.descend_to_first_item(self, |_| true);
|
|
cursor.cloned().collect()
|
|
}
|
|
|
|
pub fn cursor<'a, S, U>(&'a self) -> Cursor<'a, T, S, U>
|
|
where
|
|
S: Dimension<'a, T::Summary>,
|
|
U: Dimension<'a, T::Summary>,
|
|
{
|
|
Cursor::new(self)
|
|
}
|
|
|
|
pub fn filter<'a, F, U>(&'a self, filter_node: F) -> FilterCursor<'a, F, T, U>
|
|
where
|
|
F: Fn(&T::Summary) -> bool,
|
|
U: Dimension<'a, T::Summary>,
|
|
{
|
|
FilterCursor::new(self, filter_node)
|
|
}
|
|
|
|
#[allow(dead_code)]
|
|
pub fn first(&self) -> Option<&T> {
|
|
self.leftmost_leaf().0.items().first()
|
|
}
|
|
|
|
pub fn last(&self) -> Option<&T> {
|
|
self.rightmost_leaf().0.items().last()
|
|
}
|
|
|
|
pub fn extent<'a, D: Dimension<'a, T::Summary>>(&'a self) -> D {
|
|
let mut extent = D::default();
|
|
match self.0.as_ref() {
|
|
Node::Internal { summary, .. } | Node::Leaf { summary, .. } => {
|
|
extent.add_summary(summary)
|
|
}
|
|
}
|
|
extent
|
|
}
|
|
|
|
pub fn summary(&self) -> T::Summary {
|
|
match self.0.as_ref() {
|
|
Node::Internal { summary, .. } => summary.clone(),
|
|
Node::Leaf { summary, .. } => summary.clone(),
|
|
}
|
|
}
|
|
|
|
pub fn extend<I>(&mut self, iter: I)
|
|
where
|
|
I: IntoIterator<Item = T>,
|
|
{
|
|
let mut leaf: Option<Node<T>> = None;
|
|
|
|
for item in iter {
|
|
if leaf.is_some() && leaf.as_ref().unwrap().items().len() == 2 * TREE_BASE {
|
|
self.push_tree(SumTree(Arc::new(leaf.take().unwrap())));
|
|
}
|
|
|
|
if leaf.is_none() {
|
|
leaf = Some(Node::Leaf::<T> {
|
|
summary: T::Summary::default(),
|
|
items: ArrayVec::new(),
|
|
item_summaries: ArrayVec::new(),
|
|
});
|
|
}
|
|
|
|
if let Some(Node::Leaf {
|
|
summary,
|
|
items,
|
|
item_summaries,
|
|
}) = leaf.as_mut()
|
|
{
|
|
let item_summary = item.summary();
|
|
*summary += &item_summary;
|
|
items.push(item);
|
|
item_summaries.push(item_summary);
|
|
} else {
|
|
unreachable!()
|
|
}
|
|
}
|
|
|
|
if leaf.is_some() {
|
|
self.push_tree(SumTree(Arc::new(leaf.take().unwrap())));
|
|
}
|
|
}
|
|
|
|
pub fn push(&mut self, item: T) {
|
|
let summary = item.summary();
|
|
self.push_tree(SumTree::from_child_trees(vec![SumTree(Arc::new(
|
|
Node::Leaf {
|
|
summary: summary.clone(),
|
|
items: ArrayVec::from_iter(Some(item)),
|
|
item_summaries: ArrayVec::from_iter(Some(summary)),
|
|
},
|
|
))]))
|
|
}
|
|
|
|
pub fn push_tree(&mut self, other: Self) {
|
|
let other_node = other.0.clone();
|
|
if !other_node.is_leaf() || !other_node.items().is_empty() {
|
|
if self.0.height() < other_node.height() {
|
|
for tree in other_node.child_trees() {
|
|
self.push_tree(tree.clone());
|
|
}
|
|
} else if let Some(split_tree) = self.push_tree_recursive(other) {
|
|
*self = Self::from_child_trees(vec![self.clone(), split_tree]);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn push_tree_recursive(&mut self, other: SumTree<T>) -> Option<SumTree<T>> {
|
|
match Arc::make_mut(&mut self.0) {
|
|
Node::Internal {
|
|
height,
|
|
summary,
|
|
child_summaries,
|
|
child_trees,
|
|
..
|
|
} => {
|
|
let other_node = other.0.clone();
|
|
*summary += other_node.summary();
|
|
|
|
let height_delta = *height - other_node.height();
|
|
let mut summaries_to_append = ArrayVec::<T::Summary, { 2 * TREE_BASE }>::new();
|
|
let mut trees_to_append = ArrayVec::<SumTree<T>, { 2 * TREE_BASE }>::new();
|
|
if height_delta == 0 {
|
|
summaries_to_append.extend(other_node.child_summaries().iter().cloned());
|
|
trees_to_append.extend(other_node.child_trees().iter().cloned());
|
|
} else if height_delta == 1 && !other_node.is_underflowing() {
|
|
summaries_to_append.push(other_node.summary().clone());
|
|
trees_to_append.push(other)
|
|
} else {
|
|
let tree_to_append = child_trees.last_mut().unwrap().push_tree_recursive(other);
|
|
*child_summaries.last_mut().unwrap() =
|
|
child_trees.last().unwrap().0.summary().clone();
|
|
|
|
if let Some(split_tree) = tree_to_append {
|
|
summaries_to_append.push(split_tree.0.summary().clone());
|
|
trees_to_append.push(split_tree);
|
|
}
|
|
}
|
|
|
|
let child_count = child_trees.len() + trees_to_append.len();
|
|
if child_count > 2 * TREE_BASE {
|
|
let left_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
|
|
let right_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
|
|
let left_trees;
|
|
let right_trees;
|
|
|
|
let midpoint = (child_count + child_count % 2) / 2;
|
|
{
|
|
let mut all_summaries = child_summaries
|
|
.iter()
|
|
.chain(summaries_to_append.iter())
|
|
.cloned();
|
|
left_summaries = all_summaries.by_ref().take(midpoint).collect();
|
|
right_summaries = all_summaries.collect();
|
|
let mut all_trees =
|
|
child_trees.iter().chain(trees_to_append.iter()).cloned();
|
|
left_trees = all_trees.by_ref().take(midpoint).collect();
|
|
right_trees = all_trees.collect();
|
|
}
|
|
*summary = sum(left_summaries.iter());
|
|
*child_summaries = left_summaries;
|
|
*child_trees = left_trees;
|
|
|
|
Some(SumTree(Arc::new(Node::Internal {
|
|
height: *height,
|
|
summary: sum(right_summaries.iter()),
|
|
child_summaries: right_summaries,
|
|
child_trees: right_trees,
|
|
})))
|
|
} else {
|
|
child_summaries.extend(summaries_to_append);
|
|
child_trees.extend(trees_to_append);
|
|
None
|
|
}
|
|
}
|
|
Node::Leaf {
|
|
summary,
|
|
items,
|
|
item_summaries,
|
|
} => {
|
|
let other_node = other.0;
|
|
|
|
let child_count = items.len() + other_node.items().len();
|
|
if child_count > 2 * TREE_BASE {
|
|
let left_items;
|
|
let right_items;
|
|
let left_summaries;
|
|
let right_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>;
|
|
|
|
let midpoint = (child_count + child_count % 2) / 2;
|
|
{
|
|
let mut all_items = items.iter().chain(other_node.items().iter()).cloned();
|
|
left_items = all_items.by_ref().take(midpoint).collect();
|
|
right_items = all_items.collect();
|
|
|
|
let mut all_summaries = item_summaries
|
|
.iter()
|
|
.chain(other_node.child_summaries())
|
|
.cloned();
|
|
left_summaries = all_summaries.by_ref().take(midpoint).collect();
|
|
right_summaries = all_summaries.collect();
|
|
}
|
|
*items = left_items;
|
|
*item_summaries = left_summaries;
|
|
*summary = sum(item_summaries.iter());
|
|
Some(SumTree(Arc::new(Node::Leaf {
|
|
items: right_items,
|
|
summary: sum(right_summaries.iter()),
|
|
item_summaries: right_summaries,
|
|
})))
|
|
} else {
|
|
*summary += other_node.summary();
|
|
items.extend(other_node.items().iter().cloned());
|
|
item_summaries.extend(other_node.child_summaries().iter().cloned());
|
|
None
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn is_empty(&self) -> bool {
|
|
match self.0.as_ref() {
|
|
Node::Leaf { items, .. } => items.is_empty(),
|
|
Node::Internal { .. } => false,
|
|
}
|
|
}
|
|
|
|
/// Update the last element in the Sumtree with the provided f.
|
|
pub fn update_last(&mut self, f: impl FnOnce(&mut T)) {
|
|
if self.is_empty() {
|
|
log::warn!("Trying to update the last item in an empty sumtree");
|
|
return;
|
|
}
|
|
self.update_last_leaf_recursive(f);
|
|
}
|
|
|
|
fn update_last_leaf_recursive(&mut self, f: impl FnOnce(&mut T)) -> T::Summary {
|
|
match Arc::make_mut(&mut self.0) {
|
|
Node::Internal {
|
|
summary,
|
|
child_summaries,
|
|
child_trees,
|
|
..
|
|
} => {
|
|
let last_summary = child_summaries
|
|
.last_mut()
|
|
.expect("Internal node should hold at least one child");
|
|
let last_child = child_trees
|
|
.last_mut()
|
|
.expect("Internal node should hold at least one child");
|
|
// If the current node is an internal node, recursively update its last child.
|
|
*last_summary = last_child.update_last_leaf_recursive(f);
|
|
// Get the new summary after the child has been updated.
|
|
*summary = sum(child_summaries.iter());
|
|
summary.clone()
|
|
}
|
|
Node::Leaf {
|
|
summary,
|
|
items,
|
|
item_summaries,
|
|
} => {
|
|
let (item, item_summary) = (
|
|
items
|
|
.last_mut()
|
|
.expect("Leaf node should have at least one item"),
|
|
item_summaries
|
|
.last_mut()
|
|
.expect("Leaf node should have at least one item"),
|
|
);
|
|
(f)(item);
|
|
*item_summary = item.summary();
|
|
*summary = sum(item_summaries.iter());
|
|
summary.clone()
|
|
}
|
|
}
|
|
}
|
|
|
|
fn from_child_trees(child_trees: Vec<SumTree<T>>) -> Self {
|
|
let height = child_trees[0].0.height() + 1;
|
|
let mut child_summaries = ArrayVec::new();
|
|
for child in &child_trees {
|
|
child_summaries.push(child.0.summary().clone());
|
|
}
|
|
let summary = sum(child_summaries.iter());
|
|
SumTree(Arc::new(Node::Internal {
|
|
height,
|
|
summary,
|
|
child_summaries,
|
|
child_trees: ArrayVec::from_iter(child_trees),
|
|
}))
|
|
}
|
|
|
|
fn leftmost_leaf(&self) -> &Self {
|
|
match *self.0 {
|
|
Node::Leaf { .. } => self,
|
|
Node::Internal {
|
|
ref child_trees, ..
|
|
} => child_trees.first().unwrap().leftmost_leaf(),
|
|
}
|
|
}
|
|
|
|
fn rightmost_leaf(&self) -> &Self {
|
|
match *self.0 {
|
|
Node::Leaf { .. } => self,
|
|
Node::Internal {
|
|
ref child_trees, ..
|
|
} => child_trees.last().unwrap().rightmost_leaf(),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T: KeyedItem> SumTree<T> {
|
|
#[allow(dead_code)]
|
|
pub fn insert(&mut self, item: T) {
|
|
*self = {
|
|
let mut cursor = self.cursor::<T::Key, ()>();
|
|
let mut new_tree = cursor.slice(&item.key(), SeekBias::Left);
|
|
new_tree.push(item);
|
|
new_tree.push_tree(cursor.suffix());
|
|
new_tree
|
|
};
|
|
}
|
|
|
|
pub fn edit(&mut self, edits: &mut [Edit<T>]) {
|
|
if edits.is_empty() {
|
|
return;
|
|
}
|
|
|
|
edits.sort_unstable_by_key(|item| item.key());
|
|
|
|
*self = {
|
|
let mut cursor = self.cursor::<T::Key, ()>();
|
|
let mut new_tree = SumTree::new();
|
|
let mut buffered_items = Vec::new();
|
|
|
|
cursor.seek(&T::Key::default(), SeekBias::Left);
|
|
for edit in edits {
|
|
let new_key = edit.key();
|
|
let mut old_item = cursor.item();
|
|
|
|
if old_item
|
|
.as_ref()
|
|
.is_some_and(|old_item| old_item.key() < new_key)
|
|
{
|
|
new_tree.extend(buffered_items.drain(..));
|
|
let slice = cursor.slice(&new_key, SeekBias::Left);
|
|
new_tree.push_tree(slice);
|
|
old_item = cursor.item();
|
|
}
|
|
if old_item.is_some_and(|old_item| old_item.key() == new_key) {
|
|
cursor.next();
|
|
}
|
|
match edit {
|
|
Edit::Insert(item) => {
|
|
buffered_items.push(item.clone());
|
|
}
|
|
Edit::Remove(_) => {}
|
|
}
|
|
}
|
|
|
|
new_tree.extend(buffered_items);
|
|
new_tree.push_tree(cursor.suffix());
|
|
new_tree
|
|
};
|
|
}
|
|
}
|
|
|
|
#[derive(Clone, Debug)]
|
|
pub enum Node<T: Item> {
|
|
Internal {
|
|
height: u8,
|
|
summary: T::Summary,
|
|
child_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
|
|
child_trees: ArrayVec<SumTree<T>, { 2 * TREE_BASE }>,
|
|
},
|
|
Leaf {
|
|
summary: T::Summary,
|
|
items: ArrayVec<T, { 2 * TREE_BASE }>,
|
|
item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
|
|
},
|
|
}
|
|
|
|
impl<T: Item> Node<T> {
|
|
fn is_leaf(&self) -> bool {
|
|
matches!(self, Node::Leaf { .. })
|
|
}
|
|
|
|
fn height(&self) -> u8 {
|
|
match self {
|
|
Node::Internal { height, .. } => *height,
|
|
Node::Leaf { .. } => 0,
|
|
}
|
|
}
|
|
|
|
fn summary(&self) -> &T::Summary {
|
|
match self {
|
|
Node::Internal { summary, .. } => summary,
|
|
Node::Leaf { summary, .. } => summary,
|
|
}
|
|
}
|
|
|
|
fn child_summaries(&self) -> &[T::Summary] {
|
|
match self {
|
|
Node::Internal {
|
|
child_summaries, ..
|
|
} => child_summaries.as_slice(),
|
|
Node::Leaf { item_summaries, .. } => item_summaries.as_slice(),
|
|
}
|
|
}
|
|
|
|
fn child_trees(&self) -> &ArrayVec<SumTree<T>, { 2 * TREE_BASE }> {
|
|
match self {
|
|
Node::Internal { child_trees, .. } => child_trees,
|
|
Node::Leaf { .. } => panic!("Leaf nodes have no child trees"),
|
|
}
|
|
}
|
|
|
|
fn items(&self) -> &ArrayVec<T, { 2 * TREE_BASE }> {
|
|
match self {
|
|
Node::Leaf { items, .. } => items,
|
|
Node::Internal { .. } => panic!("Internal nodes have no items"),
|
|
}
|
|
}
|
|
|
|
fn is_underflowing(&self) -> bool {
|
|
match self {
|
|
Node::Internal { child_trees, .. } => child_trees.len() < TREE_BASE,
|
|
Node::Leaf { items, .. } => items.len() < TREE_BASE,
|
|
}
|
|
}
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
#[allow(dead_code)]
|
|
pub enum Edit<T: KeyedItem> {
|
|
Insert(T),
|
|
Remove(T),
|
|
}
|
|
|
|
impl<T: KeyedItem> Edit<T> {
|
|
fn key(&self) -> T::Key {
|
|
match self {
|
|
Edit::Insert(item) | Edit::Remove(item) => item.key(),
|
|
}
|
|
}
|
|
}
|
|
|
|
fn sum<'a, T, I>(iter: I) -> T
|
|
where
|
|
T: 'a + Default + AddAssign<&'a T>,
|
|
I: Iterator<Item = &'a T>,
|
|
{
|
|
let mut sum = T::default();
|
|
for value in iter {
|
|
sum += value;
|
|
}
|
|
sum
|
|
}
|
|
|
|
#[cfg(test)]
|
|
#[path = "lib_test.rs"]
|
|
mod tests;
|