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