1mod cursor;
2mod tree_map;
3
4use arrayvec::ArrayVec;
5pub use cursor::{Cursor, FilterCursor, Iter};
6use rayon::prelude::*;
7use std::marker::PhantomData;
8use std::mem;
9use std::{cmp::Ordering, fmt, iter::FromIterator, sync::Arc};
10pub use tree_map::{MapSeekTarget, TreeMap, TreeSet};
11
12#[cfg(test)]
13pub const TREE_BASE: usize = 2;
14#[cfg(not(test))]
15pub const TREE_BASE: usize = 6;
16
17/// An item that can be stored in a [`SumTree`]
18///
19/// Must be summarized by a type that implements [`Summary`]
20pub trait Item: Clone {
21 type Summary: Summary;
22
23 fn summary(&self, cx: &<Self::Summary as Summary>::Context) -> Self::Summary;
24}
25
26/// An [`Item`] whose summary has a specific key that can be used to identify it
27pub trait KeyedItem: Item {
28 type Key: for<'a> Dimension<'a, Self::Summary> + Ord;
29
30 fn key(&self) -> Self::Key;
31}
32
33/// A type that describes the Sum of all [`Item`]s in a subtree of the [`SumTree`]
34///
35/// Each Summary type can have multiple [`Dimension`]s that it measures,
36/// which can be used to navigate the tree
37pub trait Summary: Clone {
38 type Context;
39
40 fn zero(cx: &Self::Context) -> Self;
41 fn add_summary(&mut self, summary: &Self, cx: &Self::Context);
42}
43
44/// Catch-all implementation for when you need something that implements [`Summary`] without a specific type.
45/// We implement it on a &'static, as that avoids blanket impl collisions with `impl<T: Summary> Dimension for T`
46/// (as we also need unit type to be a fill-in dimension)
47impl Summary for &'static () {
48 type Context = ();
49
50 fn zero(_: &()) -> Self {
51 &()
52 }
53
54 fn add_summary(&mut self, _: &Self, _: &()) {}
55}
56
57/// Each [`Summary`] type can have more than one [`Dimension`] type that it measures.
58///
59/// You can use dimensions to seek to a specific location in the [`SumTree`]
60///
61/// # Example:
62/// Zed's rope has a `TextSummary` type that summarizes lines, characters, and bytes.
63/// Each of these are different dimensions we may want to seek to
64pub trait Dimension<'a, S: Summary>: Clone {
65 fn zero(cx: &S::Context) -> Self;
66
67 fn add_summary(&mut self, summary: &'a S, cx: &S::Context);
68
69 fn from_summary(summary: &'a S, cx: &S::Context) -> Self {
70 let mut dimension = Self::zero(cx);
71 dimension.add_summary(summary, cx);
72 dimension
73 }
74}
75
76impl<'a, T: Summary> Dimension<'a, T> for T {
77 fn zero(cx: &T::Context) -> Self {
78 Summary::zero(cx)
79 }
80
81 fn add_summary(&mut self, summary: &'a T, cx: &T::Context) {
82 Summary::add_summary(self, summary, cx);
83 }
84}
85
86pub trait SeekTarget<'a, S: Summary, D: Dimension<'a, S>> {
87 fn cmp(&self, cursor_location: &D, cx: &S::Context) -> Ordering;
88}
89
90impl<'a, S: Summary, D: Dimension<'a, S> + Ord> SeekTarget<'a, S, D> for D {
91 fn cmp(&self, cursor_location: &Self, _: &S::Context) -> Ordering {
92 Ord::cmp(self, cursor_location)
93 }
94}
95
96impl<'a, T: Summary> Dimension<'a, T> for () {
97 fn zero(_: &T::Context) -> Self {
98 ()
99 }
100
101 fn add_summary(&mut self, _: &'a T, _: &T::Context) {}
102}
103
104impl<'a, T: Summary, D1: Dimension<'a, T>, D2: Dimension<'a, T>> Dimension<'a, T> for (D1, D2) {
105 fn zero(cx: &T::Context) -> Self {
106 (D1::zero(cx), D2::zero(cx))
107 }
108
109 fn add_summary(&mut self, summary: &'a T, cx: &T::Context) {
110 self.0.add_summary(summary, cx);
111 self.1.add_summary(summary, cx);
112 }
113}
114
115impl<'a, S, D1, D2> SeekTarget<'a, S, (D1, D2)> for D1
116where
117 S: Summary,
118 D1: SeekTarget<'a, S, D1> + Dimension<'a, S>,
119 D2: Dimension<'a, S>,
120{
121 fn cmp(&self, cursor_location: &(D1, D2), cx: &S::Context) -> Ordering {
122 self.cmp(&cursor_location.0, cx)
123 }
124}
125
126impl<'a, S, D1, D2, D3> SeekTarget<'a, S, ((D1, D2), D3)> for D1
127where
128 S: Summary,
129 D1: SeekTarget<'a, S, D1> + Dimension<'a, S>,
130 D2: Dimension<'a, S>,
131 D3: Dimension<'a, S>,
132{
133 fn cmp(&self, cursor_location: &((D1, D2), D3), cx: &S::Context) -> Ordering {
134 self.cmp(&cursor_location.0.0, cx)
135 }
136}
137
138/// Bias is used to settle ambiguities when determining positions in an ordered sequence.
139///
140/// The primary use case is for text, where Bias influences
141/// which character an offset or anchor is associated with.
142///
143/// # Examples
144/// Given the buffer `AˇBCD`:
145/// - The offset of the cursor is 1
146/// - [Bias::Left] would attach the cursor to the character `A`
147/// - [Bias::Right] would attach the cursor to the character `B`
148///
149/// Given the buffer `A«BCˇ»D`:
150/// - The offset of the cursor is 3, and the selection is from 1 to 3
151/// - The left anchor of the selection has [Bias::Right], attaching it to the character `B`
152/// - The right anchor of the selection has [Bias::Left], attaching it to the character `C`
153///
154/// Given the buffer `{ˇ<...>`, where `<...>` is a folded region:
155/// - The display offset of the cursor is 1, but the offset in the buffer is determined by the bias
156/// - [Bias::Left] would attach the cursor to the character `{`, with a buffer offset of 1
157/// - [Bias::Right] would attach the cursor to the first character of the folded region,
158/// and the buffer offset would be the offset of the first character of the folded region
159#[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Debug, Hash, Default)]
160pub enum Bias {
161 /// Attach to the character on the left
162 #[default]
163 Left,
164 /// Attach to the character on the right
165 Right,
166}
167
168impl Bias {
169 pub fn invert(self) -> Self {
170 match self {
171 Self::Left => Self::Right,
172 Self::Right => Self::Left,
173 }
174 }
175}
176
177/// A B+ tree in which each leaf node contains `Item`s of type `T` and a `Summary`s for each `Item`.
178/// Each internal node contains a `Summary` of the items in its subtree.
179///
180/// The maximum number of items per node is `TREE_BASE * 2`.
181///
182/// Any [`Dimension`] supported by the [`Summary`] type can be used to seek to a specific location in the tree.
183#[derive(Clone)]
184pub struct SumTree<T: Item>(Arc<Node<T>>);
185
186impl<T> fmt::Debug for SumTree<T>
187where
188 T: fmt::Debug + Item,
189 T::Summary: fmt::Debug,
190{
191 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
192 f.debug_tuple("SumTree").field(&self.0).finish()
193 }
194}
195
196impl<T: Item> SumTree<T> {
197 pub fn new(cx: &<T::Summary as Summary>::Context) -> Self {
198 SumTree(Arc::new(Node::Leaf {
199 summary: <T::Summary as Summary>::zero(cx),
200 items: ArrayVec::new(),
201 item_summaries: ArrayVec::new(),
202 }))
203 }
204
205 /// Useful in cases where the item type has a non-trivial context type, but the zero value of the summary type doesn't depend on that context.
206 pub fn from_summary(summary: T::Summary) -> Self {
207 SumTree(Arc::new(Node::Leaf {
208 summary,
209 items: ArrayVec::new(),
210 item_summaries: ArrayVec::new(),
211 }))
212 }
213
214 pub fn from_item(item: T, cx: &<T::Summary as Summary>::Context) -> Self {
215 let mut tree = Self::new(cx);
216 tree.push(item, cx);
217 tree
218 }
219
220 pub fn from_iter<I: IntoIterator<Item = T>>(
221 iter: I,
222 cx: &<T::Summary as Summary>::Context,
223 ) -> Self {
224 let mut nodes = Vec::new();
225
226 let mut iter = iter.into_iter().fuse().peekable();
227 while iter.peek().is_some() {
228 let items: ArrayVec<T, { 2 * TREE_BASE }> = iter.by_ref().take(2 * TREE_BASE).collect();
229 let item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }> =
230 items.iter().map(|item| item.summary(cx)).collect();
231
232 let mut summary = item_summaries[0].clone();
233 for item_summary in &item_summaries[1..] {
234 <T::Summary as Summary>::add_summary(&mut summary, item_summary, cx);
235 }
236
237 nodes.push(Node::Leaf {
238 summary,
239 items,
240 item_summaries,
241 });
242 }
243
244 let mut parent_nodes = Vec::new();
245 let mut height = 0;
246 while nodes.len() > 1 {
247 height += 1;
248 let mut current_parent_node = None;
249 for child_node in nodes.drain(..) {
250 let parent_node = current_parent_node.get_or_insert_with(|| Node::Internal {
251 summary: <T::Summary as Summary>::zero(cx),
252 height,
253 child_summaries: ArrayVec::new(),
254 child_trees: ArrayVec::new(),
255 });
256 let Node::Internal {
257 summary,
258 child_summaries,
259 child_trees,
260 ..
261 } = parent_node
262 else {
263 unreachable!()
264 };
265 let child_summary = child_node.summary();
266 <T::Summary as Summary>::add_summary(summary, child_summary, cx);
267 child_summaries.push(child_summary.clone());
268 child_trees.push(Self(Arc::new(child_node)));
269
270 if child_trees.len() == 2 * TREE_BASE {
271 parent_nodes.extend(current_parent_node.take());
272 }
273 }
274 parent_nodes.extend(current_parent_node.take());
275 mem::swap(&mut nodes, &mut parent_nodes);
276 }
277
278 if nodes.is_empty() {
279 Self::new(cx)
280 } else {
281 debug_assert_eq!(nodes.len(), 1);
282 Self(Arc::new(nodes.pop().unwrap()))
283 }
284 }
285
286 pub fn from_par_iter<I, Iter>(iter: I, cx: &<T::Summary as Summary>::Context) -> Self
287 where
288 I: IntoParallelIterator<Iter = Iter>,
289 Iter: IndexedParallelIterator<Item = T>,
290 T: Send + Sync,
291 T::Summary: Send + Sync,
292 <T::Summary as Summary>::Context: Sync,
293 {
294 let mut nodes = iter
295 .into_par_iter()
296 .chunks(2 * TREE_BASE)
297 .map(|items| {
298 let items: ArrayVec<T, { 2 * TREE_BASE }> = items.into_iter().collect();
299 let item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }> =
300 items.iter().map(|item| item.summary(cx)).collect();
301 let mut summary = item_summaries[0].clone();
302 for item_summary in &item_summaries[1..] {
303 <T::Summary as Summary>::add_summary(&mut summary, item_summary, cx);
304 }
305 SumTree(Arc::new(Node::Leaf {
306 summary,
307 items,
308 item_summaries,
309 }))
310 })
311 .collect::<Vec<_>>();
312
313 let mut height = 0;
314 while nodes.len() > 1 {
315 height += 1;
316 nodes = nodes
317 .into_par_iter()
318 .chunks(2 * TREE_BASE)
319 .map(|child_nodes| {
320 let child_trees: ArrayVec<SumTree<T>, { 2 * TREE_BASE }> =
321 child_nodes.into_iter().collect();
322 let child_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }> = child_trees
323 .iter()
324 .map(|child_tree| child_tree.summary().clone())
325 .collect();
326 let mut summary = child_summaries[0].clone();
327 for child_summary in &child_summaries[1..] {
328 <T::Summary as Summary>::add_summary(&mut summary, child_summary, cx);
329 }
330 SumTree(Arc::new(Node::Internal {
331 height,
332 summary,
333 child_summaries,
334 child_trees,
335 }))
336 })
337 .collect::<Vec<_>>();
338 }
339
340 if nodes.is_empty() {
341 Self::new(cx)
342 } else {
343 debug_assert_eq!(nodes.len(), 1);
344 nodes.pop().unwrap()
345 }
346 }
347
348 #[allow(unused)]
349 pub fn items(&self, cx: &<T::Summary as Summary>::Context) -> Vec<T> {
350 let mut items = Vec::new();
351 let mut cursor = self.cursor::<()>(cx);
352 cursor.next();
353 while let Some(item) = cursor.item() {
354 items.push(item.clone());
355 cursor.next();
356 }
357 items
358 }
359
360 pub fn iter(&self) -> Iter<'_, T> {
361 Iter::new(self)
362 }
363
364 pub fn cursor<'a, S>(&'a self, cx: &'a <T::Summary as Summary>::Context) -> Cursor<'a, T, S>
365 where
366 S: Dimension<'a, T::Summary>,
367 {
368 Cursor::new(self, cx)
369 }
370
371 /// Note: If the summary type requires a non `()` context, then the filter cursor
372 /// that is returned cannot be used with Rust's iterators.
373 pub fn filter<'a, F, U>(
374 &'a self,
375 cx: &'a <T::Summary as Summary>::Context,
376 filter_node: F,
377 ) -> FilterCursor<'a, F, T, U>
378 where
379 F: FnMut(&T::Summary) -> bool,
380 U: Dimension<'a, T::Summary>,
381 {
382 FilterCursor::new(self, cx, filter_node)
383 }
384
385 #[allow(dead_code)]
386 pub fn first(&self) -> Option<&T> {
387 self.leftmost_leaf().0.items().first()
388 }
389
390 pub fn last(&self) -> Option<&T> {
391 self.rightmost_leaf().0.items().last()
392 }
393
394 pub fn update_last(&mut self, f: impl FnOnce(&mut T), cx: &<T::Summary as Summary>::Context) {
395 self.update_last_recursive(f, cx);
396 }
397
398 fn update_last_recursive(
399 &mut self,
400 f: impl FnOnce(&mut T),
401 cx: &<T::Summary as Summary>::Context,
402 ) -> Option<T::Summary> {
403 match Arc::make_mut(&mut self.0) {
404 Node::Internal {
405 summary,
406 child_summaries,
407 child_trees,
408 ..
409 } => {
410 let last_summary = child_summaries.last_mut().unwrap();
411 let last_child = child_trees.last_mut().unwrap();
412 *last_summary = last_child.update_last_recursive(f, cx).unwrap();
413 *summary = sum(child_summaries.iter(), cx);
414 Some(summary.clone())
415 }
416 Node::Leaf {
417 summary,
418 items,
419 item_summaries,
420 } => {
421 if let Some((item, item_summary)) = items.last_mut().zip(item_summaries.last_mut())
422 {
423 (f)(item);
424 *item_summary = item.summary(cx);
425 *summary = sum(item_summaries.iter(), cx);
426 Some(summary.clone())
427 } else {
428 None
429 }
430 }
431 }
432 }
433
434 pub fn extent<'a, D: Dimension<'a, T::Summary>>(
435 &'a self,
436 cx: &<T::Summary as Summary>::Context,
437 ) -> D {
438 let mut extent = D::zero(cx);
439 match self.0.as_ref() {
440 Node::Internal { summary, .. } | Node::Leaf { summary, .. } => {
441 extent.add_summary(summary, cx);
442 }
443 }
444 extent
445 }
446
447 pub fn summary(&self) -> &T::Summary {
448 match self.0.as_ref() {
449 Node::Internal { summary, .. } => summary,
450 Node::Leaf { summary, .. } => summary,
451 }
452 }
453
454 pub fn is_empty(&self) -> bool {
455 match self.0.as_ref() {
456 Node::Internal { .. } => false,
457 Node::Leaf { items, .. } => items.is_empty(),
458 }
459 }
460
461 pub fn extend<I>(&mut self, iter: I, cx: &<T::Summary as Summary>::Context)
462 where
463 I: IntoIterator<Item = T>,
464 {
465 self.append(Self::from_iter(iter, cx), cx);
466 }
467
468 pub fn par_extend<I, Iter>(&mut self, iter: I, cx: &<T::Summary as Summary>::Context)
469 where
470 I: IntoParallelIterator<Iter = Iter>,
471 Iter: IndexedParallelIterator<Item = T>,
472 T: Send + Sync,
473 T::Summary: Send + Sync,
474 <T::Summary as Summary>::Context: Sync,
475 {
476 self.append(Self::from_par_iter(iter, cx), cx);
477 }
478
479 pub fn push(&mut self, item: T, cx: &<T::Summary as Summary>::Context) {
480 let summary = item.summary(cx);
481 self.append(
482 SumTree(Arc::new(Node::Leaf {
483 summary: summary.clone(),
484 items: ArrayVec::from_iter(Some(item)),
485 item_summaries: ArrayVec::from_iter(Some(summary)),
486 })),
487 cx,
488 );
489 }
490
491 pub fn append(&mut self, other: Self, cx: &<T::Summary as Summary>::Context) {
492 if self.is_empty() {
493 *self = other;
494 } else if !other.0.is_leaf() || !other.0.items().is_empty() {
495 if self.0.height() < other.0.height() {
496 for tree in other.0.child_trees() {
497 self.append(tree.clone(), cx);
498 }
499 } else if let Some(split_tree) = self.push_tree_recursive(other, cx) {
500 *self = Self::from_child_trees(self.clone(), split_tree, cx);
501 }
502 }
503 }
504
505 fn push_tree_recursive(
506 &mut self,
507 other: SumTree<T>,
508 cx: &<T::Summary as Summary>::Context,
509 ) -> Option<SumTree<T>> {
510 match Arc::make_mut(&mut self.0) {
511 Node::Internal {
512 height,
513 summary,
514 child_summaries,
515 child_trees,
516 ..
517 } => {
518 let other_node = other.0.clone();
519 <T::Summary as Summary>::add_summary(summary, other_node.summary(), cx);
520
521 let height_delta = *height - other_node.height();
522 let mut summaries_to_append = ArrayVec::<T::Summary, { 2 * TREE_BASE }>::new();
523 let mut trees_to_append = ArrayVec::<SumTree<T>, { 2 * TREE_BASE }>::new();
524 if height_delta == 0 {
525 summaries_to_append.extend(other_node.child_summaries().iter().cloned());
526 trees_to_append.extend(other_node.child_trees().iter().cloned());
527 } else if height_delta == 1 && !other_node.is_underflowing() {
528 summaries_to_append.push(other_node.summary().clone());
529 trees_to_append.push(other)
530 } else {
531 let tree_to_append = child_trees
532 .last_mut()
533 .unwrap()
534 .push_tree_recursive(other, cx);
535 *child_summaries.last_mut().unwrap() =
536 child_trees.last().unwrap().0.summary().clone();
537
538 if let Some(split_tree) = tree_to_append {
539 summaries_to_append.push(split_tree.0.summary().clone());
540 trees_to_append.push(split_tree);
541 }
542 }
543
544 let child_count = child_trees.len() + trees_to_append.len();
545 if child_count > 2 * TREE_BASE {
546 let left_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
547 let right_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
548 let left_trees;
549 let right_trees;
550
551 let midpoint = (child_count + child_count % 2) / 2;
552 {
553 let mut all_summaries = child_summaries
554 .iter()
555 .chain(summaries_to_append.iter())
556 .cloned();
557 left_summaries = all_summaries.by_ref().take(midpoint).collect();
558 right_summaries = all_summaries.collect();
559 let mut all_trees =
560 child_trees.iter().chain(trees_to_append.iter()).cloned();
561 left_trees = all_trees.by_ref().take(midpoint).collect();
562 right_trees = all_trees.collect();
563 }
564 *summary = sum(left_summaries.iter(), cx);
565 *child_summaries = left_summaries;
566 *child_trees = left_trees;
567
568 Some(SumTree(Arc::new(Node::Internal {
569 height: *height,
570 summary: sum(right_summaries.iter(), cx),
571 child_summaries: right_summaries,
572 child_trees: right_trees,
573 })))
574 } else {
575 child_summaries.extend(summaries_to_append);
576 child_trees.extend(trees_to_append);
577 None
578 }
579 }
580 Node::Leaf {
581 summary,
582 items,
583 item_summaries,
584 } => {
585 let other_node = other.0;
586
587 let child_count = items.len() + other_node.items().len();
588 if child_count > 2 * TREE_BASE {
589 let left_items;
590 let right_items;
591 let left_summaries;
592 let right_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>;
593
594 let midpoint = (child_count + child_count % 2) / 2;
595 {
596 let mut all_items = items.iter().chain(other_node.items().iter()).cloned();
597 left_items = all_items.by_ref().take(midpoint).collect();
598 right_items = all_items.collect();
599
600 let mut all_summaries = item_summaries
601 .iter()
602 .chain(other_node.child_summaries())
603 .cloned();
604 left_summaries = all_summaries.by_ref().take(midpoint).collect();
605 right_summaries = all_summaries.collect();
606 }
607 *items = left_items;
608 *item_summaries = left_summaries;
609 *summary = sum(item_summaries.iter(), cx);
610 Some(SumTree(Arc::new(Node::Leaf {
611 items: right_items,
612 summary: sum(right_summaries.iter(), cx),
613 item_summaries: right_summaries,
614 })))
615 } else {
616 <T::Summary as Summary>::add_summary(summary, other_node.summary(), cx);
617 items.extend(other_node.items().iter().cloned());
618 item_summaries.extend(other_node.child_summaries().iter().cloned());
619 None
620 }
621 }
622 }
623 }
624
625 fn from_child_trees(
626 left: SumTree<T>,
627 right: SumTree<T>,
628 cx: &<T::Summary as Summary>::Context,
629 ) -> Self {
630 let height = left.0.height() + 1;
631 let mut child_summaries = ArrayVec::new();
632 child_summaries.push(left.0.summary().clone());
633 child_summaries.push(right.0.summary().clone());
634 let mut child_trees = ArrayVec::new();
635 child_trees.push(left);
636 child_trees.push(right);
637 SumTree(Arc::new(Node::Internal {
638 height,
639 summary: sum(child_summaries.iter(), cx),
640 child_summaries,
641 child_trees,
642 }))
643 }
644
645 fn leftmost_leaf(&self) -> &Self {
646 match *self.0 {
647 Node::Leaf { .. } => self,
648 Node::Internal {
649 ref child_trees, ..
650 } => child_trees.first().unwrap().leftmost_leaf(),
651 }
652 }
653
654 fn rightmost_leaf(&self) -> &Self {
655 match *self.0 {
656 Node::Leaf { .. } => self,
657 Node::Internal {
658 ref child_trees, ..
659 } => child_trees.last().unwrap().rightmost_leaf(),
660 }
661 }
662}
663
664impl<T: Item + PartialEq> PartialEq for SumTree<T> {
665 fn eq(&self, other: &Self) -> bool {
666 self.iter().eq(other.iter())
667 }
668}
669
670impl<T: Item + Eq> Eq for SumTree<T> {}
671
672impl<T: KeyedItem> SumTree<T> {
673 pub fn insert_or_replace(
674 &mut self,
675 item: T,
676 cx: &<T::Summary as Summary>::Context,
677 ) -> Option<T> {
678 let mut replaced = None;
679 *self = {
680 let mut cursor = self.cursor::<T::Key>(cx);
681 let mut new_tree = cursor.slice(&item.key(), Bias::Left);
682 if let Some(cursor_item) = cursor.item() {
683 if cursor_item.key() == item.key() {
684 replaced = Some(cursor_item.clone());
685 cursor.next();
686 }
687 }
688 new_tree.push(item, cx);
689 new_tree.append(cursor.suffix(), cx);
690 new_tree
691 };
692 replaced
693 }
694
695 pub fn remove(&mut self, key: &T::Key, cx: &<T::Summary as Summary>::Context) -> Option<T> {
696 let mut removed = None;
697 *self = {
698 let mut cursor = self.cursor::<T::Key>(cx);
699 let mut new_tree = cursor.slice(key, Bias::Left);
700 if let Some(item) = cursor.item() {
701 if item.key() == *key {
702 removed = Some(item.clone());
703 cursor.next();
704 }
705 }
706 new_tree.append(cursor.suffix(), cx);
707 new_tree
708 };
709 removed
710 }
711
712 pub fn edit(
713 &mut self,
714 mut edits: Vec<Edit<T>>,
715 cx: &<T::Summary as Summary>::Context,
716 ) -> Vec<T> {
717 if edits.is_empty() {
718 return Vec::new();
719 }
720
721 let mut removed = Vec::new();
722 edits.sort_unstable_by_key(|item| item.key());
723
724 *self = {
725 let mut cursor = self.cursor::<T::Key>(cx);
726 let mut new_tree = SumTree::new(cx);
727 let mut buffered_items = Vec::new();
728
729 cursor.seek(&T::Key::zero(cx), Bias::Left);
730 for edit in edits {
731 let new_key = edit.key();
732 let mut old_item = cursor.item();
733
734 if old_item
735 .as_ref()
736 .map_or(false, |old_item| old_item.key() < new_key)
737 {
738 new_tree.extend(buffered_items.drain(..), cx);
739 let slice = cursor.slice(&new_key, Bias::Left);
740 new_tree.append(slice, cx);
741 old_item = cursor.item();
742 }
743
744 if let Some(old_item) = old_item {
745 if old_item.key() == new_key {
746 removed.push(old_item.clone());
747 cursor.next();
748 }
749 }
750
751 match edit {
752 Edit::Insert(item) => {
753 buffered_items.push(item);
754 }
755 Edit::Remove(_) => {}
756 }
757 }
758
759 new_tree.extend(buffered_items, cx);
760 new_tree.append(cursor.suffix(), cx);
761 new_tree
762 };
763
764 removed
765 }
766
767 pub fn get<'a>(
768 &'a self,
769 key: &T::Key,
770 cx: &'a <T::Summary as Summary>::Context,
771 ) -> Option<&'a T> {
772 let mut cursor = self.cursor::<T::Key>(cx);
773 if cursor.seek(key, Bias::Left) {
774 cursor.item()
775 } else {
776 None
777 }
778 }
779}
780
781impl<T, S> Default for SumTree<T>
782where
783 T: Item<Summary = S>,
784 S: Summary<Context = ()>,
785{
786 fn default() -> Self {
787 Self::new(&())
788 }
789}
790
791#[derive(Clone)]
792pub enum Node<T: Item> {
793 Internal {
794 height: u8,
795 summary: T::Summary,
796 child_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
797 child_trees: ArrayVec<SumTree<T>, { 2 * TREE_BASE }>,
798 },
799 Leaf {
800 summary: T::Summary,
801 items: ArrayVec<T, { 2 * TREE_BASE }>,
802 item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
803 },
804}
805
806impl<T> fmt::Debug for Node<T>
807where
808 T: Item + fmt::Debug,
809 T::Summary: fmt::Debug,
810{
811 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
812 match self {
813 Node::Internal {
814 height,
815 summary,
816 child_summaries,
817 child_trees,
818 } => f
819 .debug_struct("Internal")
820 .field("height", height)
821 .field("summary", summary)
822 .field("child_summaries", child_summaries)
823 .field("child_trees", child_trees)
824 .finish(),
825 Node::Leaf {
826 summary,
827 items,
828 item_summaries,
829 } => f
830 .debug_struct("Leaf")
831 .field("summary", summary)
832 .field("items", items)
833 .field("item_summaries", item_summaries)
834 .finish(),
835 }
836 }
837}
838
839impl<T: Item> Node<T> {
840 fn is_leaf(&self) -> bool {
841 matches!(self, Node::Leaf { .. })
842 }
843
844 fn height(&self) -> u8 {
845 match self {
846 Node::Internal { height, .. } => *height,
847 Node::Leaf { .. } => 0,
848 }
849 }
850
851 fn summary(&self) -> &T::Summary {
852 match self {
853 Node::Internal { summary, .. } => summary,
854 Node::Leaf { summary, .. } => summary,
855 }
856 }
857
858 fn child_summaries(&self) -> &[T::Summary] {
859 match self {
860 Node::Internal {
861 child_summaries, ..
862 } => child_summaries.as_slice(),
863 Node::Leaf { item_summaries, .. } => item_summaries.as_slice(),
864 }
865 }
866
867 fn child_trees(&self) -> &ArrayVec<SumTree<T>, { 2 * TREE_BASE }> {
868 match self {
869 Node::Internal { child_trees, .. } => child_trees,
870 Node::Leaf { .. } => panic!("Leaf nodes have no child trees"),
871 }
872 }
873
874 fn items(&self) -> &ArrayVec<T, { 2 * TREE_BASE }> {
875 match self {
876 Node::Leaf { items, .. } => items,
877 Node::Internal { .. } => panic!("Internal nodes have no items"),
878 }
879 }
880
881 fn is_underflowing(&self) -> bool {
882 match self {
883 Node::Internal { child_trees, .. } => child_trees.len() < TREE_BASE,
884 Node::Leaf { items, .. } => items.len() < TREE_BASE,
885 }
886 }
887}
888
889#[derive(Debug)]
890pub enum Edit<T: KeyedItem> {
891 Insert(T),
892 Remove(T::Key),
893}
894
895impl<T: KeyedItem> Edit<T> {
896 fn key(&self) -> T::Key {
897 match self {
898 Edit::Insert(item) => item.key(),
899 Edit::Remove(key) => key.clone(),
900 }
901 }
902}
903
904fn sum<'a, T, I>(iter: I, cx: &T::Context) -> T
905where
906 T: 'a + Summary,
907 I: Iterator<Item = &'a T>,
908{
909 let mut sum = T::zero(cx);
910 for value in iter {
911 sum.add_summary(value, cx);
912 }
913 sum
914}
915
916#[cfg(test)]
917mod tests {
918 use super::*;
919 use rand::{distributions, prelude::*};
920 use std::cmp;
921
922 #[ctor::ctor]
923 fn init_logger() {
924 zlog::init_test();
925 }
926
927 #[test]
928 fn test_extend_and_push_tree() {
929 let mut tree1 = SumTree::default();
930 tree1.extend(0..20, &());
931
932 let mut tree2 = SumTree::default();
933 tree2.extend(50..100, &());
934
935 tree1.append(tree2, &());
936 assert_eq!(
937 tree1.items(&()),
938 (0..20).chain(50..100).collect::<Vec<u8>>()
939 );
940 }
941
942 #[test]
943 fn test_random() {
944 let mut starting_seed = 0;
945 if let Ok(value) = std::env::var("SEED") {
946 starting_seed = value.parse().expect("invalid SEED variable");
947 }
948 let mut num_iterations = 100;
949 if let Ok(value) = std::env::var("ITERATIONS") {
950 num_iterations = value.parse().expect("invalid ITERATIONS variable");
951 }
952 let num_operations = std::env::var("OPERATIONS")
953 .map_or(5, |o| o.parse().expect("invalid OPERATIONS variable"));
954
955 for seed in starting_seed..(starting_seed + num_iterations) {
956 eprintln!("seed = {}", seed);
957 let mut rng = StdRng::seed_from_u64(seed);
958
959 let rng = &mut rng;
960 let mut tree = SumTree::<u8>::default();
961 let count = rng.gen_range(0..10);
962 if rng.r#gen() {
963 tree.extend(rng.sample_iter(distributions::Standard).take(count), &());
964 } else {
965 let items = rng
966 .sample_iter(distributions::Standard)
967 .take(count)
968 .collect::<Vec<_>>();
969 tree.par_extend(items, &());
970 }
971
972 for _ in 0..num_operations {
973 let splice_end = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
974 let splice_start = rng.gen_range(0..splice_end + 1);
975 let count = rng.gen_range(0..10);
976 let tree_end = tree.extent::<Count>(&());
977 let new_items = rng
978 .sample_iter(distributions::Standard)
979 .take(count)
980 .collect::<Vec<u8>>();
981
982 let mut reference_items = tree.items(&());
983 reference_items.splice(splice_start..splice_end, new_items.clone());
984
985 tree = {
986 let mut cursor = tree.cursor::<Count>(&());
987 let mut new_tree = cursor.slice(&Count(splice_start), Bias::Right);
988 if rng.r#gen() {
989 new_tree.extend(new_items, &());
990 } else {
991 new_tree.par_extend(new_items, &());
992 }
993 cursor.seek(&Count(splice_end), Bias::Right);
994 new_tree.append(cursor.slice(&tree_end, Bias::Right), &());
995 new_tree
996 };
997
998 assert_eq!(tree.items(&()), reference_items);
999 assert_eq!(
1000 tree.iter().collect::<Vec<_>>(),
1001 tree.cursor::<()>(&()).collect::<Vec<_>>()
1002 );
1003
1004 log::info!("tree items: {:?}", tree.items(&()));
1005
1006 let mut filter_cursor =
1007 tree.filter::<_, Count>(&(), |summary| summary.contains_even);
1008 let expected_filtered_items = tree
1009 .items(&())
1010 .into_iter()
1011 .enumerate()
1012 .filter(|(_, item)| (item & 1) == 0)
1013 .collect::<Vec<_>>();
1014
1015 let mut item_ix = if rng.r#gen() {
1016 filter_cursor.next();
1017 0
1018 } else {
1019 filter_cursor.prev();
1020 expected_filtered_items.len().saturating_sub(1)
1021 };
1022 while item_ix < expected_filtered_items.len() {
1023 log::info!("filter_cursor, item_ix: {}", item_ix);
1024 let actual_item = filter_cursor.item().unwrap();
1025 let (reference_index, reference_item) = expected_filtered_items[item_ix];
1026 assert_eq!(actual_item, &reference_item);
1027 assert_eq!(filter_cursor.start().0, reference_index);
1028 log::info!("next");
1029 filter_cursor.next();
1030 item_ix += 1;
1031
1032 while item_ix > 0 && rng.gen_bool(0.2) {
1033 log::info!("prev");
1034 filter_cursor.prev();
1035 item_ix -= 1;
1036
1037 if item_ix == 0 && rng.gen_bool(0.2) {
1038 filter_cursor.prev();
1039 assert_eq!(filter_cursor.item(), None);
1040 assert_eq!(filter_cursor.start().0, 0);
1041 filter_cursor.next();
1042 }
1043 }
1044 }
1045 assert_eq!(filter_cursor.item(), None);
1046
1047 let mut before_start = false;
1048 let mut cursor = tree.cursor::<Count>(&());
1049 let start_pos = rng.gen_range(0..=reference_items.len());
1050 cursor.seek(&Count(start_pos), Bias::Right);
1051 let mut pos = rng.gen_range(start_pos..=reference_items.len());
1052 cursor.seek_forward(&Count(pos), Bias::Right);
1053
1054 for i in 0..10 {
1055 assert_eq!(cursor.start().0, pos);
1056
1057 if pos > 0 {
1058 assert_eq!(cursor.prev_item().unwrap(), &reference_items[pos - 1]);
1059 } else {
1060 assert_eq!(cursor.prev_item(), None);
1061 }
1062
1063 if pos < reference_items.len() && !before_start {
1064 assert_eq!(cursor.item().unwrap(), &reference_items[pos]);
1065 } else {
1066 assert_eq!(cursor.item(), None);
1067 }
1068
1069 if before_start {
1070 assert_eq!(cursor.next_item(), reference_items.first());
1071 } else if pos + 1 < reference_items.len() {
1072 assert_eq!(cursor.next_item().unwrap(), &reference_items[pos + 1]);
1073 } else {
1074 assert_eq!(cursor.next_item(), None);
1075 }
1076
1077 if i < 5 {
1078 cursor.next();
1079 if pos < reference_items.len() {
1080 pos += 1;
1081 before_start = false;
1082 }
1083 } else {
1084 cursor.prev();
1085 if pos == 0 {
1086 before_start = true;
1087 }
1088 pos = pos.saturating_sub(1);
1089 }
1090 }
1091 }
1092
1093 for _ in 0..10 {
1094 let end = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
1095 let start = rng.gen_range(0..end + 1);
1096 let start_bias = if rng.r#gen() { Bias::Left } else { Bias::Right };
1097 let end_bias = if rng.r#gen() { Bias::Left } else { Bias::Right };
1098
1099 let mut cursor = tree.cursor::<Count>(&());
1100 cursor.seek(&Count(start), start_bias);
1101 let slice = cursor.slice(&Count(end), end_bias);
1102
1103 cursor.seek(&Count(start), start_bias);
1104 let summary = cursor.summary::<_, Sum>(&Count(end), end_bias);
1105
1106 assert_eq!(summary.0, slice.summary().sum);
1107 }
1108 }
1109 }
1110
1111 #[test]
1112 fn test_cursor() {
1113 // Empty tree
1114 let tree = SumTree::<u8>::default();
1115 let mut cursor = tree.cursor::<IntegersSummary>(&());
1116 assert_eq!(
1117 cursor.slice(&Count(0), Bias::Right).items(&()),
1118 Vec::<u8>::new()
1119 );
1120 assert_eq!(cursor.item(), None);
1121 assert_eq!(cursor.prev_item(), None);
1122 assert_eq!(cursor.next_item(), None);
1123 assert_eq!(cursor.start().sum, 0);
1124 cursor.prev();
1125 assert_eq!(cursor.item(), None);
1126 assert_eq!(cursor.prev_item(), None);
1127 assert_eq!(cursor.next_item(), None);
1128 assert_eq!(cursor.start().sum, 0);
1129 cursor.next();
1130 assert_eq!(cursor.item(), None);
1131 assert_eq!(cursor.prev_item(), None);
1132 assert_eq!(cursor.next_item(), None);
1133 assert_eq!(cursor.start().sum, 0);
1134
1135 // Single-element tree
1136 let mut tree = SumTree::<u8>::default();
1137 tree.extend(vec![1], &());
1138 let mut cursor = tree.cursor::<IntegersSummary>(&());
1139 assert_eq!(
1140 cursor.slice(&Count(0), Bias::Right).items(&()),
1141 Vec::<u8>::new()
1142 );
1143 assert_eq!(cursor.item(), Some(&1));
1144 assert_eq!(cursor.prev_item(), None);
1145 assert_eq!(cursor.next_item(), None);
1146 assert_eq!(cursor.start().sum, 0);
1147
1148 cursor.next();
1149 assert_eq!(cursor.item(), None);
1150 assert_eq!(cursor.prev_item(), Some(&1));
1151 assert_eq!(cursor.next_item(), None);
1152 assert_eq!(cursor.start().sum, 1);
1153
1154 cursor.prev();
1155 assert_eq!(cursor.item(), Some(&1));
1156 assert_eq!(cursor.prev_item(), None);
1157 assert_eq!(cursor.next_item(), None);
1158 assert_eq!(cursor.start().sum, 0);
1159
1160 let mut cursor = tree.cursor::<IntegersSummary>(&());
1161 assert_eq!(cursor.slice(&Count(1), Bias::Right).items(&()), [1]);
1162 assert_eq!(cursor.item(), None);
1163 assert_eq!(cursor.prev_item(), Some(&1));
1164 assert_eq!(cursor.next_item(), None);
1165 assert_eq!(cursor.start().sum, 1);
1166
1167 cursor.seek(&Count(0), Bias::Right);
1168 assert_eq!(
1169 cursor
1170 .slice(&tree.extent::<Count>(&()), Bias::Right)
1171 .items(&()),
1172 [1]
1173 );
1174 assert_eq!(cursor.item(), None);
1175 assert_eq!(cursor.prev_item(), Some(&1));
1176 assert_eq!(cursor.next_item(), None);
1177 assert_eq!(cursor.start().sum, 1);
1178
1179 // Multiple-element tree
1180 let mut tree = SumTree::default();
1181 tree.extend(vec![1, 2, 3, 4, 5, 6], &());
1182 let mut cursor = tree.cursor::<IntegersSummary>(&());
1183
1184 assert_eq!(cursor.slice(&Count(2), Bias::Right).items(&()), [1, 2]);
1185 assert_eq!(cursor.item(), Some(&3));
1186 assert_eq!(cursor.prev_item(), Some(&2));
1187 assert_eq!(cursor.next_item(), Some(&4));
1188 assert_eq!(cursor.start().sum, 3);
1189
1190 cursor.next();
1191 assert_eq!(cursor.item(), Some(&4));
1192 assert_eq!(cursor.prev_item(), Some(&3));
1193 assert_eq!(cursor.next_item(), Some(&5));
1194 assert_eq!(cursor.start().sum, 6);
1195
1196 cursor.next();
1197 assert_eq!(cursor.item(), Some(&5));
1198 assert_eq!(cursor.prev_item(), Some(&4));
1199 assert_eq!(cursor.next_item(), Some(&6));
1200 assert_eq!(cursor.start().sum, 10);
1201
1202 cursor.next();
1203 assert_eq!(cursor.item(), Some(&6));
1204 assert_eq!(cursor.prev_item(), Some(&5));
1205 assert_eq!(cursor.next_item(), None);
1206 assert_eq!(cursor.start().sum, 15);
1207
1208 cursor.next();
1209 cursor.next();
1210 assert_eq!(cursor.item(), None);
1211 assert_eq!(cursor.prev_item(), Some(&6));
1212 assert_eq!(cursor.next_item(), None);
1213 assert_eq!(cursor.start().sum, 21);
1214
1215 cursor.prev();
1216 assert_eq!(cursor.item(), Some(&6));
1217 assert_eq!(cursor.prev_item(), Some(&5));
1218 assert_eq!(cursor.next_item(), None);
1219 assert_eq!(cursor.start().sum, 15);
1220
1221 cursor.prev();
1222 assert_eq!(cursor.item(), Some(&5));
1223 assert_eq!(cursor.prev_item(), Some(&4));
1224 assert_eq!(cursor.next_item(), Some(&6));
1225 assert_eq!(cursor.start().sum, 10);
1226
1227 cursor.prev();
1228 assert_eq!(cursor.item(), Some(&4));
1229 assert_eq!(cursor.prev_item(), Some(&3));
1230 assert_eq!(cursor.next_item(), Some(&5));
1231 assert_eq!(cursor.start().sum, 6);
1232
1233 cursor.prev();
1234 assert_eq!(cursor.item(), Some(&3));
1235 assert_eq!(cursor.prev_item(), Some(&2));
1236 assert_eq!(cursor.next_item(), Some(&4));
1237 assert_eq!(cursor.start().sum, 3);
1238
1239 cursor.prev();
1240 assert_eq!(cursor.item(), Some(&2));
1241 assert_eq!(cursor.prev_item(), Some(&1));
1242 assert_eq!(cursor.next_item(), Some(&3));
1243 assert_eq!(cursor.start().sum, 1);
1244
1245 cursor.prev();
1246 assert_eq!(cursor.item(), Some(&1));
1247 assert_eq!(cursor.prev_item(), None);
1248 assert_eq!(cursor.next_item(), Some(&2));
1249 assert_eq!(cursor.start().sum, 0);
1250
1251 cursor.prev();
1252 assert_eq!(cursor.item(), None);
1253 assert_eq!(cursor.prev_item(), None);
1254 assert_eq!(cursor.next_item(), Some(&1));
1255 assert_eq!(cursor.start().sum, 0);
1256
1257 cursor.next();
1258 assert_eq!(cursor.item(), Some(&1));
1259 assert_eq!(cursor.prev_item(), None);
1260 assert_eq!(cursor.next_item(), Some(&2));
1261 assert_eq!(cursor.start().sum, 0);
1262
1263 let mut cursor = tree.cursor::<IntegersSummary>(&());
1264 assert_eq!(
1265 cursor
1266 .slice(&tree.extent::<Count>(&()), Bias::Right)
1267 .items(&()),
1268 tree.items(&())
1269 );
1270 assert_eq!(cursor.item(), None);
1271 assert_eq!(cursor.prev_item(), Some(&6));
1272 assert_eq!(cursor.next_item(), None);
1273 assert_eq!(cursor.start().sum, 21);
1274
1275 cursor.seek(&Count(3), Bias::Right);
1276 assert_eq!(
1277 cursor
1278 .slice(&tree.extent::<Count>(&()), Bias::Right)
1279 .items(&()),
1280 [4, 5, 6]
1281 );
1282 assert_eq!(cursor.item(), None);
1283 assert_eq!(cursor.prev_item(), Some(&6));
1284 assert_eq!(cursor.next_item(), None);
1285 assert_eq!(cursor.start().sum, 21);
1286
1287 // Seeking can bias left or right
1288 cursor.seek(&Count(1), Bias::Left);
1289 assert_eq!(cursor.item(), Some(&1));
1290 cursor.seek(&Count(1), Bias::Right);
1291 assert_eq!(cursor.item(), Some(&2));
1292
1293 // Slicing without resetting starts from where the cursor is parked at.
1294 cursor.seek(&Count(1), Bias::Right);
1295 assert_eq!(cursor.slice(&Count(3), Bias::Right).items(&()), vec![2, 3]);
1296 assert_eq!(cursor.slice(&Count(6), Bias::Left).items(&()), vec![4, 5]);
1297 assert_eq!(cursor.slice(&Count(6), Bias::Right).items(&()), vec![6]);
1298 }
1299
1300 #[test]
1301 fn test_edit() {
1302 let mut tree = SumTree::<u8>::default();
1303
1304 let removed = tree.edit(vec![Edit::Insert(1), Edit::Insert(2), Edit::Insert(0)], &());
1305 assert_eq!(tree.items(&()), vec![0, 1, 2]);
1306 assert_eq!(removed, Vec::<u8>::new());
1307 assert_eq!(tree.get(&0, &()), Some(&0));
1308 assert_eq!(tree.get(&1, &()), Some(&1));
1309 assert_eq!(tree.get(&2, &()), Some(&2));
1310 assert_eq!(tree.get(&4, &()), None);
1311
1312 let removed = tree.edit(vec![Edit::Insert(2), Edit::Insert(4), Edit::Remove(0)], &());
1313 assert_eq!(tree.items(&()), vec![1, 2, 4]);
1314 assert_eq!(removed, vec![0, 2]);
1315 assert_eq!(tree.get(&0, &()), None);
1316 assert_eq!(tree.get(&1, &()), Some(&1));
1317 assert_eq!(tree.get(&2, &()), Some(&2));
1318 assert_eq!(tree.get(&4, &()), Some(&4));
1319 }
1320
1321 #[test]
1322 fn test_from_iter() {
1323 assert_eq!(
1324 SumTree::from_iter(0..100, &()).items(&()),
1325 (0..100).collect::<Vec<_>>()
1326 );
1327
1328 // Ensure `from_iter` works correctly when the given iterator restarts
1329 // after calling `next` if `None` was already returned.
1330 let mut ix = 0;
1331 let iterator = std::iter::from_fn(|| {
1332 ix = (ix + 1) % 2;
1333 if ix == 1 { Some(1) } else { None }
1334 });
1335 assert_eq!(SumTree::from_iter(iterator, &()).items(&()), vec![1]);
1336 }
1337
1338 #[derive(Clone, Default, Debug)]
1339 pub struct IntegersSummary {
1340 count: usize,
1341 sum: usize,
1342 contains_even: bool,
1343 max: u8,
1344 }
1345
1346 #[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
1347 struct Count(usize);
1348
1349 #[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
1350 struct Sum(usize);
1351
1352 impl Item for u8 {
1353 type Summary = IntegersSummary;
1354
1355 fn summary(&self, _cx: &()) -> Self::Summary {
1356 IntegersSummary {
1357 count: 1,
1358 sum: *self as usize,
1359 contains_even: (*self & 1) == 0,
1360 max: *self,
1361 }
1362 }
1363 }
1364
1365 impl KeyedItem for u8 {
1366 type Key = u8;
1367
1368 fn key(&self) -> Self::Key {
1369 *self
1370 }
1371 }
1372
1373 impl Summary for IntegersSummary {
1374 type Context = ();
1375
1376 fn zero(_cx: &()) -> Self {
1377 Default::default()
1378 }
1379
1380 fn add_summary(&mut self, other: &Self, _: &()) {
1381 self.count += other.count;
1382 self.sum += other.sum;
1383 self.contains_even |= other.contains_even;
1384 self.max = cmp::max(self.max, other.max);
1385 }
1386 }
1387
1388 impl Dimension<'_, IntegersSummary> for u8 {
1389 fn zero(_cx: &()) -> Self {
1390 Default::default()
1391 }
1392
1393 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1394 *self = summary.max;
1395 }
1396 }
1397
1398 impl Dimension<'_, IntegersSummary> for Count {
1399 fn zero(_cx: &()) -> Self {
1400 Default::default()
1401 }
1402
1403 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1404 self.0 += summary.count;
1405 }
1406 }
1407
1408 impl SeekTarget<'_, IntegersSummary, IntegersSummary> for Count {
1409 fn cmp(&self, cursor_location: &IntegersSummary, _: &()) -> Ordering {
1410 self.0.cmp(&cursor_location.count)
1411 }
1412 }
1413
1414 impl Dimension<'_, IntegersSummary> for Sum {
1415 fn zero(_cx: &()) -> Self {
1416 Default::default()
1417 }
1418
1419 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1420 self.0 += summary.sum;
1421 }
1422 }
1423}