1mod cursor;
2mod tree_map;
3
4use arrayvec::ArrayVec;
5pub use cursor::{Cursor, FilterCursor, Iter};
6use rayon::prelude::*;
7use std::borrow::Cow;
8use std::marker::PhantomData;
9use std::mem;
10use std::{cmp::Ordering, fmt, iter::FromIterator, sync::Arc};
11pub use tree_map::{MapSeekTarget, TreeMap, TreeSet};
12
13#[cfg(test)]
14pub const TREE_BASE: usize = 2;
15#[cfg(not(test))]
16pub const TREE_BASE: usize = 6;
17
18/// An item that can be stored in a [`SumTree`]
19///
20/// Must be summarized by a type that implements [`Summary`]
21pub trait Item: Clone {
22 type Summary: Summary;
23
24 fn summary(&self, cx: &<Self::Summary as Summary>::Context) -> Self::Summary;
25}
26
27/// An [`Item`] whose summary has a specific key that can be used to identify it
28pub trait KeyedItem: Item {
29 type Key: for<'a> Dimension<'a, Self::Summary> + Ord;
30
31 fn key(&self) -> Self::Key;
32}
33
34/// A type that describes the Sum of all [`Item`]s in a subtree of the [`SumTree`]
35///
36/// Each Summary type can have multiple [`Dimension`]s that it measures,
37/// which can be used to navigate the tree
38pub trait Summary: Clone {
39 type Context;
40
41 fn zero(cx: &Self::Context) -> Self;
42 fn add_summary(&mut self, summary: &Self, cx: &Self::Context);
43 fn sub_summary(&mut self, _: &Self, _: &Self::Context) {}
44}
45
46/// Catch-all implementation for when you need something that implements [`Summary`] without a specific type.
47/// We implement it on a &'static, as that avoids blanket impl collisions with `impl<T: Summary> Dimension for T`
48/// (as we also need unit type to be a fill-in dimension)
49impl Summary for &'static () {
50 type Context = ();
51
52 fn zero(_: &()) -> Self {
53 &()
54 }
55
56 fn add_summary(&mut self, _: &Self, _: &()) {}
57 // fn sub_summary(&mut self, _: &Self, _: &()) {}
58}
59
60/// Each [`Summary`] type can have more than one [`Dimension`] type that it measures.
61///
62/// You can use dimensions to seek to a specific location in the [`SumTree`]
63///
64/// # Example:
65/// Zed's rope has a `TextSummary` type that summarizes lines, characters, and bytes.
66/// Each of these are different dimensions we may want to seek to
67pub trait Dimension<'a, S: Summary>: Clone {
68 fn zero(cx: &S::Context) -> Self;
69
70 fn add_summary(&mut self, summary: &'a S, cx: &S::Context);
71
72 fn from_summary(summary: &'a S, cx: &S::Context) -> Self {
73 let mut dimension = Self::zero(cx);
74 dimension.add_summary(summary, cx);
75 dimension
76 }
77}
78
79impl<'a, T: Summary> Dimension<'a, T> for T {
80 fn zero(cx: &T::Context) -> Self {
81 Summary::zero(cx)
82 }
83
84 fn add_summary(&mut self, summary: &'a T, cx: &T::Context) {
85 Summary::add_summary(self, summary, cx);
86 }
87}
88
89pub trait SeekTarget<'a, S: Summary, D: Dimension<'a, S>> {
90 fn cmp(&self, cursor_location: &D, cx: &S::Context) -> Ordering;
91}
92
93impl<'a, S: Summary, D: Dimension<'a, S> + Ord> SeekTarget<'a, S, D> for D {
94 fn cmp(&self, cursor_location: &Self, _: &S::Context) -> Ordering {
95 Ord::cmp(self, cursor_location)
96 }
97}
98
99impl<'a, T: Summary> Dimension<'a, T> for () {
100 fn zero(_: &T::Context) -> Self {
101 ()
102 }
103
104 fn add_summary(&mut self, _: &'a T, _: &T::Context) {}
105}
106
107#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
108pub struct Dimensions<D1, D2, D3 = ()>(pub D1, pub D2, pub D3);
109
110impl<'a, T: Summary, D1: Dimension<'a, T>, D2: Dimension<'a, T>, D3: Dimension<'a, T>>
111 Dimension<'a, T> for Dimensions<D1, D2, D3>
112{
113 fn zero(cx: &T::Context) -> Self {
114 Dimensions(D1::zero(cx), D2::zero(cx), D3::zero(cx))
115 }
116
117 fn add_summary(&mut self, summary: &'a T, cx: &T::Context) {
118 self.0.add_summary(summary, cx);
119 self.1.add_summary(summary, cx);
120 self.2.add_summary(summary, cx);
121 }
122}
123
124impl<'a, S, D1, D2, D3> SeekTarget<'a, S, Dimensions<D1, D2, D3>> for D1
125where
126 S: Summary,
127 D1: SeekTarget<'a, S, D1> + Dimension<'a, S>,
128 D2: Dimension<'a, S>,
129 D3: Dimension<'a, S>,
130{
131 fn cmp(&self, cursor_location: &Dimensions<D1, D2, D3>, cx: &S::Context) -> Ordering {
132 self.cmp(&cursor_location.0, cx)
133 }
134}
135
136/// Bias is used to settle ambiguities when determining positions in an ordered sequence.
137///
138/// The primary use case is for text, where Bias influences
139/// which character an offset or anchor is associated with.
140///
141/// # Examples
142/// Given the buffer `AˇBCD`:
143/// - The offset of the cursor is 1
144/// - [Bias::Left] would attach the cursor to the character `A`
145/// - [Bias::Right] would attach the cursor to the character `B`
146///
147/// Given the buffer `A«BCˇ»D`:
148/// - The offset of the cursor is 3, and the selection is from 1 to 3
149/// - The left anchor of the selection has [Bias::Right], attaching it to the character `B`
150/// - The right anchor of the selection has [Bias::Left], attaching it to the character `C`
151///
152/// Given the buffer `{ˇ<...>`, where `<...>` is a folded region:
153/// - The display offset of the cursor is 1, but the offset in the buffer is determined by the bias
154/// - [Bias::Left] would attach the cursor to the character `{`, with a buffer offset of 1
155/// - [Bias::Right] would attach the cursor to the first character of the folded region,
156/// and the buffer offset would be the offset of the first character of the folded region
157#[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Debug, Hash, Default)]
158pub enum Bias {
159 /// Attach to the character on the left
160 #[default]
161 Left,
162 /// Attach to the character on the right
163 Right,
164}
165
166impl Bias {
167 pub fn invert(self) -> Self {
168 match self {
169 Self::Left => Self::Right,
170 Self::Right => Self::Left,
171 }
172 }
173}
174
175/// A B+ tree in which each leaf node contains `Item`s of type `T` and a `Summary`s for each `Item`.
176/// Each internal node contains a `Summary` of the items in its subtree.
177///
178/// The maximum number of items per node is `TREE_BASE * 2`.
179///
180/// Any [`Dimension`] supported by the [`Summary`] type can be used to seek to a specific location in the tree.
181#[derive(Clone)]
182pub struct SumTree<T: Item>(Arc<Node<T>>);
183
184impl<T> fmt::Debug for SumTree<T>
185where
186 T: fmt::Debug + Item,
187 T::Summary: fmt::Debug,
188{
189 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
190 f.debug_tuple("SumTree").field(&self.0).finish()
191 }
192}
193
194impl<T: Item> SumTree<T> {
195 pub fn new() -> Self {
196 SumTree(Arc::new(Node::Leaf {
197 items: ArrayVec::new(),
198 item_summaries: ArrayVec::new(),
199 }))
200 }
201
202 pub fn from_item(item: T, cx: &<T::Summary as Summary>::Context) -> Self {
203 let mut tree = Self::new();
204 tree.push(item, cx);
205 tree
206 }
207
208 pub fn from_iter<I: IntoIterator<Item = T>>(
209 iter: I,
210 cx: &<T::Summary as Summary>::Context,
211 ) -> Self {
212 let mut nodes = Vec::new();
213
214 let mut iter = iter.into_iter().fuse().peekable();
215 while iter.peek().is_some() {
216 let items: ArrayVec<T, { 2 * TREE_BASE }> = iter.by_ref().take(2 * TREE_BASE).collect();
217 let item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }> =
218 items.iter().map(|item| item.summary(cx)).collect();
219
220 let mut summary = item_summaries[0].clone();
221 for item_summary in &item_summaries[1..] {
222 <T::Summary as Summary>::add_summary(&mut summary, item_summary, cx);
223 }
224
225 nodes.push(Node::Leaf {
226 items,
227 item_summaries,
228 });
229 }
230
231 let mut parent_nodes = Vec::new();
232 let mut height = 0;
233 while nodes.len() > 1 {
234 height += 1;
235 let mut current_parent_node = None;
236 for child_node in nodes.drain(..) {
237 let parent_node = current_parent_node.get_or_insert_with(|| Node::Internal {
238 height,
239 child_summaries: ArrayVec::new(),
240 child_trees: ArrayVec::new(),
241 });
242 let Node::Internal {
243 child_summaries,
244 child_trees,
245 ..
246 } = parent_node
247 else {
248 unreachable!()
249 };
250 let child_summary = child_node.summary_or_zero(cx);
251 let child_summary = if let Some(mut last) = child_summaries.last().cloned() {
252 <T::Summary as Summary>::add_summary(&mut last, &child_summary, cx);
253 last
254 } else {
255 child_summary.into_owned()
256 };
257
258 child_summaries.push(child_summary);
259 child_trees.push(Self(Arc::new(child_node)));
260
261 if child_trees.len() == 2 * TREE_BASE {
262 parent_nodes.extend(current_parent_node.take());
263 }
264 }
265 parent_nodes.extend(current_parent_node.take());
266 mem::swap(&mut nodes, &mut parent_nodes);
267 }
268
269 if nodes.is_empty() {
270 Self::new()
271 } else {
272 debug_assert_eq!(nodes.len(), 1);
273 Self(Arc::new(nodes.pop().unwrap()))
274 }
275 }
276
277 pub fn from_par_iter<I, Iter>(iter: I, cx: &<T::Summary as Summary>::Context) -> Self
278 where
279 I: IntoParallelIterator<Iter = Iter>,
280 Iter: IndexedParallelIterator<Item = T>,
281 T: Send + Sync,
282 T::Summary: Send + Sync,
283 <T::Summary as Summary>::Context: Sync,
284 {
285 let mut nodes = iter
286 .into_par_iter()
287 .chunks(2 * TREE_BASE)
288 .map(|items| {
289 let items: ArrayVec<T, { 2 * TREE_BASE }> = items.into_iter().collect();
290 let item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }> = items
291 .iter()
292 .scan(None, |previous_item, item| {
293 let summary = item.summary(cx);
294 let current_item = if let Some(mut base) = previous_item.take() {
295 <T::Summary as Summary>::add_summary(&mut base, &summary, cx);
296 base
297 } else {
298 summary
299 };
300 _ = previous_item.insert(current_item.clone());
301 Some(current_item)
302 })
303 .collect();
304
305 SumTree(Arc::new(Node::Leaf {
306 items,
307 item_summaries,
308 }))
309 })
310 .collect::<Vec<_>>();
311
312 let mut height = 0;
313 while nodes.len() > 1 {
314 height += 1;
315 nodes = nodes
316 .into_par_iter()
317 .chunks(2 * TREE_BASE)
318 .map(|child_nodes| {
319 let child_trees: ArrayVec<SumTree<T>, { 2 * TREE_BASE }> =
320 child_nodes.into_iter().collect();
321 let child_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }> = child_trees
322 .iter()
323 .map(|child_tree| child_tree.0.summary_or_zero(cx).into_owned())
324 .collect();
325 let mut summary = child_summaries[0].clone();
326 for child_summary in &child_summaries[1..] {
327 <T::Summary as Summary>::add_summary(&mut summary, child_summary, cx);
328 }
329 SumTree(Arc::new(Node::Internal {
330 height,
331
332 child_summaries,
333 child_trees,
334 }))
335 })
336 .collect::<Vec<_>>();
337 }
338
339 if nodes.is_empty() {
340 Self::new()
341 } else {
342 debug_assert_eq!(nodes.len(), 1);
343 nodes.pop().unwrap()
344 }
345 }
346
347 #[allow(unused)]
348 pub fn items(&self, cx: &<T::Summary as Summary>::Context) -> Vec<T> {
349 let mut items = Vec::new();
350 let mut cursor = self.cursor::<()>(cx);
351 cursor.next();
352 while let Some(item) = cursor.item() {
353 items.push(item.clone());
354 cursor.next();
355 }
356 items
357 }
358
359 pub fn iter(&self) -> Iter<'_, T> {
360 Iter::new(self)
361 }
362
363 pub fn cursor<'a, S>(&'a self, cx: &'a <T::Summary as Summary>::Context) -> Cursor<'a, T, S>
364 where
365 S: Dimension<'a, T::Summary>,
366 {
367 Cursor::new(self, cx)
368 }
369
370 /// Note: If the summary type requires a non `()` context, then the filter cursor
371 /// that is returned cannot be used with Rust's iterators.
372 pub fn filter<'a, F, U>(
373 &'a self,
374 cx: &'a <T::Summary as Summary>::Context,
375 filter_node: F,
376 ) -> FilterCursor<'a, F, T, U>
377 where
378 F: FnMut(&T::Summary) -> Ordering,
379 U: Dimension<'a, T::Summary>,
380 {
381 FilterCursor::new(self, cx, filter_node)
382 }
383
384 #[allow(dead_code)]
385 pub fn first(&self) -> Option<&T> {
386 self.leftmost_leaf().0.items().first()
387 }
388
389 pub fn last(&self) -> Option<&T> {
390 self.rightmost_leaf().0.items().last()
391 }
392
393 pub fn update_last(&mut self, f: impl FnOnce(&mut T), cx: &<T::Summary as Summary>::Context) {
394 self.update_last_recursive(f, cx);
395 }
396
397 fn update_last_recursive(
398 &mut self,
399 f: impl FnOnce(&mut T),
400 cx: &<T::Summary as Summary>::Context,
401 ) -> Option<T::Summary> {
402 match Arc::make_mut(&mut self.0) {
403 Node::Internal {
404 child_summaries,
405 child_trees,
406 ..
407 } => {
408 let last_child = child_trees.last_mut().unwrap();
409
410 let mut bare_summary = last_child.update_last_recursive(f, cx).unwrap();
411
412 if let Some(mut second_to_last_summary) = child_summaries
413 .len()
414 .checked_sub(2)
415 .and_then(|ix| child_summaries.get(ix))
416 .cloned()
417 {
418 <T::Summary as Summary>::add_summary(
419 &mut second_to_last_summary,
420 &bare_summary,
421 cx,
422 );
423 bare_summary = second_to_last_summary;
424 }
425 let last_summary = child_summaries.last_mut().unwrap();
426 *last_summary = bare_summary;
427
428 Some(last_summary.clone())
429 }
430 Node::Leaf {
431 items,
432 item_summaries,
433 } => {
434 let preceding_summary = item_summaries
435 .len()
436 .checked_sub(2)
437 .and_then(|ix| item_summaries.get(ix))
438 .cloned();
439 if let Some((item, item_summary)) = items.last_mut().zip(item_summaries.last_mut())
440 {
441 (f)(item);
442 let mut bare_summary = item.summary(cx);
443
444 if let Some(mut second_to_last_summary) = preceding_summary {
445 <T::Summary as Summary>::add_summary(
446 &mut second_to_last_summary,
447 &bare_summary,
448 cx,
449 );
450 bare_summary = second_to_last_summary;
451 }
452 *item_summary = bare_summary.clone();
453
454 Some(item_summary.clone())
455 } else {
456 None
457 }
458 }
459 }
460 }
461
462 pub fn extent<'a, D: Dimension<'a, T::Summary>>(
463 &'a self,
464 cx: &<T::Summary as Summary>::Context,
465 ) -> D {
466 let mut extent = D::zero(cx);
467 if let Some(last) = self.0.child_summaries().last() {
468 extent.add_summary(last, cx);
469 }
470
471 extent
472 }
473
474 pub fn is_empty(&self) -> bool {
475 match self.0.as_ref() {
476 Node::Internal { .. } => false,
477 Node::Leaf { items, .. } => items.is_empty(),
478 }
479 }
480
481 pub fn extend<I>(&mut self, iter: I, cx: &<T::Summary as Summary>::Context)
482 where
483 I: IntoIterator<Item = T>,
484 {
485 self.append(Self::from_iter(iter, cx), cx);
486 }
487
488 pub fn par_extend<I, Iter>(&mut self, iter: I, cx: &<T::Summary as Summary>::Context)
489 where
490 I: IntoParallelIterator<Iter = Iter>,
491 Iter: IndexedParallelIterator<Item = T>,
492 T: Send + Sync,
493 T::Summary: Send + Sync,
494 <T::Summary as Summary>::Context: Sync,
495 {
496 self.append(Self::from_par_iter(iter, cx), cx);
497 }
498
499 pub fn push(&mut self, item: T, cx: &<T::Summary as Summary>::Context) {
500 let summary = item.summary(cx);
501 self.append(
502 SumTree(Arc::new(Node::Leaf {
503 items: ArrayVec::from_iter(Some(item)),
504 item_summaries: ArrayVec::from_iter(Some(summary)),
505 })),
506 cx,
507 );
508 }
509
510 pub fn append(&mut self, other: Self, cx: &<T::Summary as Summary>::Context) {
511 if self.is_empty() {
512 *self = other;
513 } else if !other.0.is_leaf() || !other.0.items().is_empty() {
514 if self.0.height() < other.0.height() {
515 for tree in other.0.child_trees() {
516 self.append(tree.clone(), cx);
517 }
518 } else if let Some(split_tree) = self.push_tree_recursive(other, cx) {
519 *self = Self::from_child_trees(self.clone(), split_tree, cx);
520 }
521 }
522 }
523
524 fn push_tree_recursive(
525 &mut self,
526 other: SumTree<T>,
527 cx: &<T::Summary as Summary>::Context,
528 ) -> Option<SumTree<T>> {
529 match Arc::make_mut(&mut self.0) {
530 Node::Internal {
531 height,
532 child_summaries,
533 child_trees,
534 ..
535 } => {
536 let other_node = other.0.clone();
537
538 let height_delta = *height - other_node.height();
539 let mut summaries_to_append = ArrayVec::<T::Summary, { 2 * TREE_BASE }>::new();
540 let mut trees_to_append = ArrayVec::<SumTree<T>, { 2 * TREE_BASE }>::new();
541 if height_delta == 0 {
542 summaries_to_append.extend(other_node.child_summaries().iter().cloned());
543 trees_to_append.extend(other_node.child_trees().iter().cloned());
544 } else if height_delta == 1 && !other_node.is_underflowing() {
545 summaries_to_append.push(other_node.summary_or_zero(cx).into_owned());
546 trees_to_append.push(other)
547 } else {
548 let tree_to_append = child_trees
549 .last_mut()
550 .unwrap()
551 .push_tree_recursive(other, cx);
552 *child_summaries.last_mut().unwrap() = child_trees
553 .last()
554 .unwrap()
555 .0
556 .summary_or_zero(cx)
557 .into_owned();
558
559 if let Some(split_tree) = tree_to_append {
560 summaries_to_append.push(split_tree.0.summary_or_zero(cx).into_owned());
561 trees_to_append.push(split_tree);
562 }
563 }
564
565 let child_count = child_trees.len() + trees_to_append.len();
566 if child_count > 2 * TREE_BASE {
567 let left_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
568 let right_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
569 let left_trees;
570 let right_trees;
571
572 let midpoint = (child_count + child_count % 2) / 2;
573 {
574 let mut all_summaries = child_summaries
575 .iter()
576 .chain(summaries_to_append.iter())
577 .cloned();
578 left_summaries = all_summaries.by_ref().take(midpoint).collect();
579 right_summaries = all_summaries.collect();
580 let mut all_trees =
581 child_trees.iter().chain(trees_to_append.iter()).cloned();
582 left_trees = all_trees.by_ref().take(midpoint).collect();
583 right_trees = all_trees.collect();
584 }
585
586 *child_summaries = left_summaries;
587 *child_trees = left_trees;
588
589 Some(SumTree(Arc::new(Node::Internal {
590 height: *height,
591 child_summaries: right_summaries,
592 child_trees: right_trees,
593 })))
594 } else {
595 child_summaries.extend(summaries_to_append);
596 child_trees.extend(trees_to_append);
597 None
598 }
599 }
600 Node::Leaf {
601 items,
602 item_summaries,
603 } => {
604 let other_node = other.0;
605
606 let child_count = items.len() + other_node.items().len();
607 if child_count > 2 * TREE_BASE {
608 let left_items;
609 let right_items;
610 let left_summaries;
611 let right_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>;
612
613 let midpoint = (child_count + child_count % 2) / 2;
614 {
615 let mut all_items = items.iter().chain(other_node.items().iter()).cloned();
616 left_items = all_items.by_ref().take(midpoint).collect();
617 right_items = all_items.collect();
618
619 let mut all_summaries = item_summaries
620 .iter()
621 .chain(other_node.child_summaries())
622 .cloned();
623 left_summaries = all_summaries.by_ref().take(midpoint).collect();
624 right_summaries = all_summaries.collect();
625 }
626 *items = left_items;
627 *item_summaries = left_summaries;
628
629 Some(SumTree(Arc::new(Node::Leaf {
630 items: right_items,
631
632 item_summaries: right_summaries,
633 })))
634 } else {
635 let baseline = item_summaries.last().cloned();
636
637 items.extend(other_node.items().iter().cloned());
638 item_summaries.extend(other_node.child_summaries().iter().map(|summary| {
639 if let Some(mut baseline) = baseline.clone() {
640 <T::Summary as Summary>::add_summary(&mut baseline, summary, cx);
641 baseline
642 } else {
643 summary.clone()
644 }
645 }));
646 None
647 }
648 }
649 }
650 }
651
652 fn from_child_trees(
653 left: SumTree<T>,
654 right: SumTree<T>,
655 cx: &<T::Summary as Summary>::Context,
656 ) -> Self {
657 let height = left.0.height() + 1;
658 let mut child_summaries = ArrayVec::new();
659 child_summaries.push(left.0.summary_or_zero(cx).into_owned());
660 child_summaries.push(right.0.summary_or_zero(cx).into_owned());
661 let mut child_trees = ArrayVec::new();
662 child_trees.push(left);
663 child_trees.push(right);
664 SumTree(Arc::new(Node::Internal {
665 height,
666
667 child_summaries,
668 child_trees,
669 }))
670 }
671
672 fn leftmost_leaf(&self) -> &Self {
673 match *self.0 {
674 Node::Leaf { .. } => self,
675 Node::Internal {
676 ref child_trees, ..
677 } => child_trees.first().unwrap().leftmost_leaf(),
678 }
679 }
680
681 fn rightmost_leaf(&self) -> &Self {
682 match *self.0 {
683 Node::Leaf { .. } => self,
684 Node::Internal {
685 ref child_trees, ..
686 } => child_trees.last().unwrap().rightmost_leaf(),
687 }
688 }
689}
690
691impl<T: Item + PartialEq> PartialEq for SumTree<T> {
692 fn eq(&self, other: &Self) -> bool {
693 self.iter().eq(other.iter())
694 }
695}
696
697impl<T: Item + Eq> Eq for SumTree<T> {}
698
699impl<T: KeyedItem> SumTree<T> {
700 pub fn insert_or_replace(
701 &mut self,
702 item: T,
703 cx: &<T::Summary as Summary>::Context,
704 ) -> Option<T> {
705 let mut replaced = None;
706 *self = {
707 let mut cursor = self.cursor::<T::Key>(cx);
708 let mut new_tree = cursor.slice(&item.key(), Bias::Left);
709 if let Some(cursor_item) = cursor.item() {
710 if cursor_item.key() == item.key() {
711 replaced = Some(cursor_item.clone());
712 cursor.next();
713 }
714 }
715 new_tree.push(item, cx);
716 new_tree.append(cursor.suffix(), cx);
717 new_tree
718 };
719 replaced
720 }
721
722 pub fn remove(&mut self, key: &T::Key, cx: &<T::Summary as Summary>::Context) -> Option<T> {
723 let mut removed = None;
724 *self = {
725 let mut cursor = self.cursor::<T::Key>(cx);
726 let mut new_tree = cursor.slice(key, Bias::Left);
727 if let Some(item) = cursor.item() {
728 if item.key() == *key {
729 removed = Some(item.clone());
730 cursor.next();
731 }
732 }
733 new_tree.append(cursor.suffix(), cx);
734 new_tree
735 };
736 removed
737 }
738
739 pub fn edit(
740 &mut self,
741 mut edits: Vec<Edit<T>>,
742 cx: &<T::Summary as Summary>::Context,
743 ) -> Vec<T> {
744 if edits.is_empty() {
745 return Vec::new();
746 }
747
748 let mut removed = Vec::new();
749 edits.sort_unstable_by_key(|item| item.key());
750
751 *self = {
752 let mut cursor = self.cursor::<T::Key>(cx);
753 let mut new_tree = SumTree::new();
754 let mut buffered_items = Vec::new();
755
756 cursor.seek(&T::Key::zero(cx), Bias::Left);
757 for edit in edits {
758 let new_key = edit.key();
759 let mut old_item = cursor.item();
760
761 if old_item
762 .as_ref()
763 .map_or(false, |old_item| old_item.key() < new_key)
764 {
765 new_tree.extend(buffered_items.drain(..), cx);
766 let slice = cursor.slice(&new_key, Bias::Left);
767 new_tree.append(slice, cx);
768 old_item = cursor.item();
769 }
770
771 if let Some(old_item) = old_item {
772 if old_item.key() == new_key {
773 removed.push(old_item.clone());
774 cursor.next();
775 }
776 }
777
778 match edit {
779 Edit::Insert(item) => {
780 buffered_items.push(item);
781 }
782 Edit::Remove(_) => {}
783 }
784 }
785
786 new_tree.extend(buffered_items, cx);
787 new_tree.append(cursor.suffix(), cx);
788 new_tree
789 };
790
791 removed
792 }
793
794 pub fn get<'a>(
795 &'a self,
796 key: &T::Key,
797 cx: &'a <T::Summary as Summary>::Context,
798 ) -> Option<&'a T> {
799 let mut cursor = self.cursor::<T::Key>(cx);
800 if cursor.seek(key, Bias::Left) {
801 cursor.item()
802 } else {
803 None
804 }
805 }
806}
807
808impl<T: Item> Default for SumTree<T> {
809 fn default() -> Self {
810 Self::new()
811 }
812}
813
814#[derive(Clone)]
815pub enum Node<T: Item> {
816 Internal {
817 height: u8,
818 child_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
819 child_trees: ArrayVec<SumTree<T>, { 2 * TREE_BASE }>,
820 },
821 Leaf {
822 items: ArrayVec<T, { 2 * TREE_BASE }>,
823 item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
824 },
825}
826
827impl<T> fmt::Debug for Node<T>
828where
829 T: Item + fmt::Debug,
830 T::Summary: fmt::Debug,
831{
832 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
833 match self {
834 Node::Internal {
835 height,
836 child_summaries,
837 child_trees,
838 } => f
839 .debug_struct("Internal")
840 .field("height", height)
841 .field("child_summaries", child_summaries)
842 .field("child_trees", child_trees)
843 .finish(),
844 Node::Leaf {
845 items,
846 item_summaries,
847 } => f
848 .debug_struct("Leaf")
849 .field("items", items)
850 .field("item_summaries", item_summaries)
851 .finish(),
852 }
853 }
854}
855
856impl<T: Item> Node<T> {
857 fn is_leaf(&self) -> bool {
858 matches!(self, Node::Leaf { .. })
859 }
860
861 fn height(&self) -> u8 {
862 match self {
863 Node::Internal { height, .. } => *height,
864 Node::Leaf { .. } => 0,
865 }
866 }
867
868 fn summary<'a>(&'a self) -> Option<&'a T::Summary> {
869 let child_summaries = self.child_summaries();
870 child_summaries.last()
871 }
872
873 fn summary_or_zero<'a>(&'a self, cx: &<T::Summary as Summary>::Context) -> Cow<'a, T::Summary> {
874 self.summary().map_or_else(
875 || Cow::Owned(<T::Summary as Summary>::zero(cx)),
876 |last_summary| Cow::Borrowed(last_summary),
877 )
878 }
879
880 fn child_summaries(&self) -> &[T::Summary] {
881 match self {
882 Node::Internal {
883 child_summaries, ..
884 } => child_summaries.as_slice(),
885 Node::Leaf { item_summaries, .. } => item_summaries.as_slice(),
886 }
887 }
888
889 fn child_trees(&self) -> &ArrayVec<SumTree<T>, { 2 * TREE_BASE }> {
890 match self {
891 Node::Internal { child_trees, .. } => child_trees,
892 Node::Leaf { .. } => panic!("Leaf nodes have no child trees"),
893 }
894 }
895
896 fn items(&self) -> &ArrayVec<T, { 2 * TREE_BASE }> {
897 match self {
898 Node::Leaf { items, .. } => items,
899 Node::Internal { .. } => panic!("Internal nodes have no items"),
900 }
901 }
902
903 fn is_underflowing(&self) -> bool {
904 match self {
905 Node::Internal { child_trees, .. } => child_trees.len() < TREE_BASE,
906 Node::Leaf { items, .. } => items.len() < TREE_BASE,
907 }
908 }
909}
910
911#[derive(Debug)]
912pub enum Edit<T: KeyedItem> {
913 Insert(T),
914 Remove(T::Key),
915}
916
917impl<T: KeyedItem> Edit<T> {
918 fn key(&self) -> T::Key {
919 match self {
920 Edit::Insert(item) => item.key(),
921 Edit::Remove(key) => key.clone(),
922 }
923 }
924}
925
926#[cfg(test)]
927mod tests {
928 use super::*;
929 use rand::{distributions, prelude::*};
930 use std::cmp;
931
932 #[ctor::ctor]
933 fn init_logger() {
934 zlog::init_test();
935 }
936
937 #[test]
938 fn test_extend_and_push_tree() {
939 let mut tree1 = SumTree::default();
940 tree1.extend(0..20, &());
941
942 let mut tree2 = SumTree::default();
943 tree2.extend(50..100, &());
944
945 tree1.append(tree2, &());
946 assert_eq!(
947 tree1.items(&()),
948 (0..20).chain(50..100).collect::<Vec<u8>>()
949 );
950 }
951
952 #[test]
953 fn test_random() {
954 let mut starting_seed = 0;
955 if let Ok(value) = std::env::var("SEED") {
956 starting_seed = value.parse().expect("invalid SEED variable");
957 }
958 let mut num_iterations = 100;
959 if let Ok(value) = std::env::var("ITERATIONS") {
960 num_iterations = value.parse().expect("invalid ITERATIONS variable");
961 }
962 let num_operations = std::env::var("OPERATIONS")
963 .map_or(5, |o| o.parse().expect("invalid OPERATIONS variable"));
964
965 for seed in starting_seed..(starting_seed + num_iterations) {
966 eprintln!("seed = {}", seed);
967 let mut rng = StdRng::seed_from_u64(seed);
968
969 let rng = &mut rng;
970 let mut tree = SumTree::<u8>::default();
971 let count = rng.gen_range(0..10);
972 if rng.r#gen() {
973 tree.extend(rng.sample_iter(distributions::Standard).take(count), &());
974 } else {
975 let items = rng
976 .sample_iter(distributions::Standard)
977 .take(count)
978 .collect::<Vec<_>>();
979 tree.par_extend(items, &());
980 }
981
982 for _ in 0..num_operations {
983 let splice_end = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
984 let splice_start = rng.gen_range(0..splice_end + 1);
985 let count = rng.gen_range(0..10);
986 let tree_end = tree.extent::<Count>(&());
987 let new_items = rng
988 .sample_iter(distributions::Standard)
989 .take(count)
990 .collect::<Vec<u8>>();
991
992 let mut reference_items = tree.items(&());
993 reference_items.splice(splice_start..splice_end, new_items.clone());
994
995 tree = {
996 let mut cursor = tree.cursor::<Count>(&());
997 let mut new_tree = cursor.slice(&Count(splice_start), Bias::Right);
998 if rng.r#gen() {
999 new_tree.extend(new_items, &());
1000 } else {
1001 new_tree.par_extend(new_items, &());
1002 }
1003 cursor.seek(&Count(splice_end), Bias::Right);
1004 new_tree.append(cursor.slice(&tree_end, Bias::Right), &());
1005 new_tree
1006 };
1007
1008 assert_eq!(tree.items(&()), reference_items);
1009 assert_eq!(
1010 tree.iter().collect::<Vec<_>>(),
1011 tree.cursor::<()>(&()).collect::<Vec<_>>()
1012 );
1013
1014 log::info!("tree items: {:?}", tree.items(&()));
1015
1016 let mut filter_cursor =
1017 tree.filter::<_, Count>(&(), |summary| summary.contains_even.cmp(&false));
1018 let expected_filtered_items = tree
1019 .items(&())
1020 .into_iter()
1021 .enumerate()
1022 .filter(|(_, item)| (item & 1) == 0)
1023 .collect::<Vec<_>>();
1024
1025 let mut item_ix = if rng.r#gen() {
1026 filter_cursor.next();
1027 0
1028 } else {
1029 filter_cursor.prev();
1030 expected_filtered_items.len().saturating_sub(1)
1031 };
1032 while item_ix < expected_filtered_items.len() {
1033 log::info!("filter_cursor, item_ix: {}", item_ix);
1034 let actual_item = filter_cursor.item().unwrap();
1035 let (reference_index, reference_item) = expected_filtered_items[item_ix];
1036 assert_eq!(actual_item, &reference_item);
1037 assert_eq!(filter_cursor.start().0, reference_index);
1038 log::info!("next");
1039 filter_cursor.next();
1040 item_ix += 1;
1041
1042 while item_ix > 0 && rng.gen_bool(0.2) {
1043 log::info!("prev");
1044 filter_cursor.prev();
1045 item_ix -= 1;
1046
1047 if item_ix == 0 && rng.gen_bool(0.2) {
1048 filter_cursor.prev();
1049 assert_eq!(filter_cursor.item(), None);
1050 assert_eq!(filter_cursor.start().0, 0);
1051 filter_cursor.next();
1052 }
1053 }
1054 }
1055 assert_eq!(filter_cursor.item(), None);
1056
1057 let mut before_start = false;
1058 let mut cursor = tree.cursor::<Count>(&());
1059 let start_pos = rng.gen_range(0..=reference_items.len());
1060 cursor.seek(&Count(start_pos), Bias::Right);
1061 let mut pos = rng.gen_range(start_pos..=reference_items.len());
1062 cursor.seek_forward(&Count(pos), Bias::Right);
1063
1064 for i in 0..10 {
1065 assert_eq!(cursor.start().0, pos);
1066
1067 if pos > 0 {
1068 assert_eq!(cursor.prev_item().unwrap(), &reference_items[pos - 1]);
1069 } else {
1070 assert_eq!(cursor.prev_item(), None);
1071 }
1072
1073 if pos < reference_items.len() && !before_start {
1074 assert_eq!(cursor.item().unwrap(), &reference_items[pos]);
1075 } else {
1076 assert_eq!(cursor.item(), None);
1077 }
1078
1079 if before_start {
1080 assert_eq!(cursor.next_item(), reference_items.first());
1081 } else if pos + 1 < reference_items.len() {
1082 assert_eq!(cursor.next_item().unwrap(), &reference_items[pos + 1]);
1083 } else {
1084 assert_eq!(cursor.next_item(), None);
1085 }
1086
1087 if i < 5 {
1088 cursor.next();
1089 if pos < reference_items.len() {
1090 pos += 1;
1091 before_start = false;
1092 }
1093 } else {
1094 cursor.prev();
1095 if pos == 0 {
1096 before_start = true;
1097 }
1098 pos = pos.saturating_sub(1);
1099 }
1100 }
1101 }
1102
1103 for _ in 0..10 {
1104 let end = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
1105 let start = rng.gen_range(0..end + 1);
1106 let start_bias = if rng.r#gen() { Bias::Left } else { Bias::Right };
1107 let end_bias = if rng.r#gen() { Bias::Left } else { Bias::Right };
1108
1109 let mut cursor = tree.cursor::<Count>(&());
1110 cursor.seek(&Count(start), start_bias);
1111 let slice = cursor.slice(&Count(end), end_bias);
1112
1113 cursor.seek(&Count(start), start_bias);
1114 let summary = cursor.summary::<_, Sum>(&Count(end), end_bias);
1115
1116 assert_eq!(summary.0, slice.0.summary_or_zero(&()).sum);
1117 }
1118 }
1119 }
1120
1121 #[test]
1122 fn test_cursor() {
1123 // Empty tree
1124 let tree = SumTree::<u8>::default();
1125 let mut cursor = tree.cursor::<IntegersSummary>(&());
1126 assert_eq!(
1127 cursor.slice(&Count(0), Bias::Right).items(&()),
1128 Vec::<u8>::new()
1129 );
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 cursor.prev();
1135 assert_eq!(cursor.item(), None);
1136 assert_eq!(cursor.prev_item(), None);
1137 assert_eq!(cursor.next_item(), None);
1138 assert_eq!(cursor.start().sum, 0);
1139 cursor.next();
1140 assert_eq!(cursor.item(), None);
1141 assert_eq!(cursor.prev_item(), None);
1142 assert_eq!(cursor.next_item(), None);
1143 assert_eq!(cursor.start().sum, 0);
1144
1145 // Single-element tree
1146 let mut tree = SumTree::<u8>::default();
1147 tree.extend(vec![1], &());
1148 let mut cursor = tree.cursor::<IntegersSummary>(&());
1149 assert_eq!(
1150 cursor.slice(&Count(0), Bias::Right).items(&()),
1151 Vec::<u8>::new()
1152 );
1153 assert_eq!(cursor.item(), Some(&1));
1154 assert_eq!(cursor.prev_item(), None);
1155 assert_eq!(cursor.next_item(), None);
1156 assert_eq!(cursor.start().sum, 0);
1157
1158 cursor.next();
1159 assert_eq!(cursor.item(), None);
1160 assert_eq!(cursor.prev_item(), Some(&1));
1161 assert_eq!(cursor.next_item(), None);
1162 assert_eq!(cursor.start().sum, 1);
1163
1164 cursor.prev();
1165 assert_eq!(cursor.item(), Some(&1));
1166 assert_eq!(cursor.prev_item(), None);
1167 assert_eq!(cursor.next_item(), None);
1168 assert_eq!(cursor.start().sum, 0);
1169
1170 let mut cursor = tree.cursor::<IntegersSummary>(&());
1171 assert_eq!(cursor.slice(&Count(1), Bias::Right).items(&()), [1]);
1172 assert_eq!(cursor.item(), None);
1173 assert_eq!(cursor.prev_item(), Some(&1));
1174 assert_eq!(cursor.next_item(), None);
1175 assert_eq!(cursor.start().sum, 1);
1176
1177 cursor.seek(&Count(0), Bias::Right);
1178 assert_eq!(
1179 cursor
1180 .slice(&tree.extent::<Count>(&()), Bias::Right)
1181 .items(&()),
1182 [1]
1183 );
1184 assert_eq!(cursor.item(), None);
1185 assert_eq!(cursor.prev_item(), Some(&1));
1186 assert_eq!(cursor.next_item(), None);
1187 assert_eq!(cursor.start().sum, 1);
1188
1189 // Multiple-element tree
1190 let mut tree = SumTree::default();
1191 tree.extend(vec![1, 2, 3, 4, 5, 6], &());
1192 let mut cursor = tree.cursor::<IntegersSummary>(&());
1193
1194 assert_eq!(cursor.slice(&Count(2), Bias::Right).items(&()), [1, 2]);
1195 assert_eq!(cursor.item(), Some(&3));
1196 assert_eq!(cursor.prev_item(), Some(&2));
1197 assert_eq!(cursor.next_item(), Some(&4));
1198 assert_eq!(cursor.start().sum, 3);
1199
1200 cursor.next();
1201 assert_eq!(cursor.item(), Some(&4));
1202 assert_eq!(cursor.prev_item(), Some(&3));
1203 assert_eq!(cursor.next_item(), Some(&5));
1204 assert_eq!(cursor.start().sum, 6);
1205
1206 cursor.next();
1207 assert_eq!(cursor.item(), Some(&5));
1208 assert_eq!(cursor.prev_item(), Some(&4));
1209 assert_eq!(cursor.next_item(), Some(&6));
1210 assert_eq!(cursor.start().sum, 10);
1211
1212 cursor.next();
1213 assert_eq!(cursor.item(), Some(&6));
1214 assert_eq!(cursor.prev_item(), Some(&5));
1215 assert_eq!(cursor.next_item(), None);
1216 assert_eq!(cursor.start().sum, 15);
1217
1218 cursor.next();
1219 cursor.next();
1220 assert_eq!(cursor.item(), None);
1221 assert_eq!(cursor.prev_item(), Some(&6));
1222 assert_eq!(cursor.next_item(), None);
1223 assert_eq!(cursor.start().sum, 21);
1224
1225 cursor.prev();
1226 assert_eq!(cursor.item(), Some(&6));
1227 assert_eq!(cursor.prev_item(), Some(&5));
1228 assert_eq!(cursor.next_item(), None);
1229 assert_eq!(cursor.start().sum, 15);
1230
1231 cursor.prev();
1232 assert_eq!(cursor.item(), Some(&5));
1233 assert_eq!(cursor.prev_item(), Some(&4));
1234 assert_eq!(cursor.next_item(), Some(&6));
1235 assert_eq!(cursor.start().sum, 10);
1236
1237 cursor.prev();
1238 assert_eq!(cursor.item(), Some(&4));
1239 assert_eq!(cursor.prev_item(), Some(&3));
1240 assert_eq!(cursor.next_item(), Some(&5));
1241 assert_eq!(cursor.start().sum, 6);
1242
1243 cursor.prev();
1244 assert_eq!(cursor.item(), Some(&3));
1245 assert_eq!(cursor.prev_item(), Some(&2));
1246 assert_eq!(cursor.next_item(), Some(&4));
1247 assert_eq!(cursor.start().sum, 3);
1248
1249 cursor.prev();
1250 assert_eq!(cursor.item(), Some(&2));
1251 assert_eq!(cursor.prev_item(), Some(&1));
1252 assert_eq!(cursor.next_item(), Some(&3));
1253 assert_eq!(cursor.start().sum, 1);
1254
1255 cursor.prev();
1256 assert_eq!(cursor.item(), Some(&1));
1257 assert_eq!(cursor.prev_item(), None);
1258 assert_eq!(cursor.next_item(), Some(&2));
1259 assert_eq!(cursor.start().sum, 0);
1260
1261 cursor.prev();
1262 assert_eq!(cursor.item(), None);
1263 assert_eq!(cursor.prev_item(), None);
1264 assert_eq!(cursor.next_item(), Some(&1));
1265 assert_eq!(cursor.start().sum, 0);
1266
1267 cursor.next();
1268 assert_eq!(cursor.item(), Some(&1));
1269 assert_eq!(cursor.prev_item(), None);
1270 assert_eq!(cursor.next_item(), Some(&2));
1271 assert_eq!(cursor.start().sum, 0);
1272
1273 let mut cursor = tree.cursor::<IntegersSummary>(&());
1274 assert_eq!(
1275 cursor
1276 .slice(&tree.extent::<Count>(&()), Bias::Right)
1277 .items(&()),
1278 tree.items(&())
1279 );
1280 assert_eq!(cursor.item(), None);
1281 assert_eq!(cursor.prev_item(), Some(&6));
1282 assert_eq!(cursor.next_item(), None);
1283 assert_eq!(cursor.start().sum, 21);
1284
1285 cursor.seek(&Count(3), Bias::Right);
1286 assert_eq!(
1287 cursor
1288 .slice(&tree.extent::<Count>(&()), Bias::Right)
1289 .items(&()),
1290 [4, 5, 6]
1291 );
1292 assert_eq!(cursor.item(), None);
1293 assert_eq!(cursor.prev_item(), Some(&6));
1294 assert_eq!(cursor.next_item(), None);
1295 assert_eq!(cursor.start().sum, 21);
1296
1297 // Seeking can bias left or right
1298 cursor.seek(&Count(1), Bias::Left);
1299 assert_eq!(cursor.item(), Some(&1));
1300 cursor.seek(&Count(1), Bias::Right);
1301 assert_eq!(cursor.item(), Some(&2));
1302
1303 // Slicing without resetting starts from where the cursor is parked at.
1304 cursor.seek(&Count(1), Bias::Right);
1305 assert_eq!(cursor.slice(&Count(3), Bias::Right).items(&()), vec![2, 3]);
1306 assert_eq!(cursor.slice(&Count(6), Bias::Left).items(&()), vec![4, 5]);
1307 assert_eq!(cursor.slice(&Count(6), Bias::Right).items(&()), vec![6]);
1308 }
1309
1310 #[test]
1311 fn test_edit() {
1312 let mut tree = SumTree::<u8>::default();
1313
1314 let removed = tree.edit(vec![Edit::Insert(1), Edit::Insert(2), Edit::Insert(0)], &());
1315 assert_eq!(tree.items(&()), vec![0, 1, 2]);
1316 assert_eq!(removed, Vec::<u8>::new());
1317 assert_eq!(tree.get(&0, &()), Some(&0));
1318 assert_eq!(tree.get(&1, &()), Some(&1));
1319 assert_eq!(tree.get(&2, &()), Some(&2));
1320 assert_eq!(tree.get(&4, &()), None);
1321
1322 let removed = tree.edit(vec![Edit::Insert(2), Edit::Insert(4), Edit::Remove(0)], &());
1323 assert_eq!(tree.items(&()), vec![1, 2, 4]);
1324 assert_eq!(removed, vec![0, 2]);
1325 assert_eq!(tree.get(&0, &()), None);
1326 assert_eq!(tree.get(&1, &()), Some(&1));
1327 assert_eq!(tree.get(&2, &()), Some(&2));
1328 assert_eq!(tree.get(&4, &()), Some(&4));
1329 }
1330
1331 #[test]
1332 fn test_from_iter() {
1333 assert_eq!(
1334 SumTree::from_iter(0..100, &()).items(&()),
1335 (0..100).collect::<Vec<_>>()
1336 );
1337
1338 // Ensure `from_iter` works correctly when the given iterator restarts
1339 // after calling `next` if `None` was already returned.
1340 let mut ix = 0;
1341 let iterator = std::iter::from_fn(|| {
1342 ix = (ix + 1) % 2;
1343 if ix == 1 { Some(1) } else { None }
1344 });
1345 assert_eq!(SumTree::from_iter(iterator, &()).items(&()), vec![1]);
1346 }
1347
1348 #[derive(Clone, Default, Debug)]
1349 pub struct IntegersSummary {
1350 count: usize,
1351 sum: usize,
1352 contains_even: bool,
1353 max: u8,
1354 }
1355
1356 #[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
1357 struct Count(usize);
1358
1359 #[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
1360 struct Sum(usize);
1361
1362 impl Item for u8 {
1363 type Summary = IntegersSummary;
1364
1365 fn summary(&self, _cx: &()) -> Self::Summary {
1366 IntegersSummary {
1367 count: 1,
1368 sum: *self as usize,
1369 contains_even: (*self & 1) == 0,
1370 max: *self,
1371 }
1372 }
1373 }
1374
1375 impl KeyedItem for u8 {
1376 type Key = u8;
1377
1378 fn key(&self) -> Self::Key {
1379 *self
1380 }
1381 }
1382
1383 impl Summary for IntegersSummary {
1384 type Context = ();
1385
1386 fn zero(_cx: &()) -> Self {
1387 Default::default()
1388 }
1389
1390 fn add_summary(&mut self, other: &Self, _: &()) {
1391 self.count += other.count;
1392 self.sum += other.sum;
1393 self.contains_even |= other.contains_even;
1394 self.max = cmp::max(self.max, other.max);
1395 }
1396 }
1397
1398 impl Dimension<'_, IntegersSummary> for u8 {
1399 fn zero(_cx: &()) -> Self {
1400 Default::default()
1401 }
1402
1403 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1404 *self = summary.max;
1405 }
1406 }
1407
1408 impl Dimension<'_, IntegersSummary> for Count {
1409 fn zero(_cx: &()) -> Self {
1410 Default::default()
1411 }
1412
1413 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1414 self.0 += summary.count;
1415 }
1416 }
1417
1418 impl SeekTarget<'_, IntegersSummary, IntegersSummary> for Count {
1419 fn cmp(&self, cursor_location: &IntegersSummary, _: &()) -> Ordering {
1420 self.0.cmp(&cursor_location.count)
1421 }
1422 }
1423
1424 impl Dimension<'_, IntegersSummary> for Sum {
1425 fn zero(_cx: &()) -> Self {
1426 Default::default()
1427 }
1428
1429 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1430 self.0 += summary.sum;
1431 }
1432 }
1433}