1mod cursor;
2mod tree_map;
3
4use arrayvec::ArrayVec;
5pub use cursor::{Cursor, FilterCursor, Iter};
6use std::marker::PhantomData;
7use std::{cmp::Ordering, fmt, iter::FromIterator, sync::Arc};
8pub use tree_map::{MapSeekTarget, TreeMap, TreeSet};
9
10#[cfg(test)]
11const TREE_BASE: usize = 2;
12#[cfg(not(test))]
13const TREE_BASE: usize = 6;
14
15pub trait Item: Clone {
16 type Summary: Summary;
17
18 fn summary(&self) -> Self::Summary;
19}
20
21pub trait KeyedItem: Item {
22 type Key: for<'a> Dimension<'a, Self::Summary> + Ord;
23
24 fn key(&self) -> Self::Key;
25}
26
27pub trait Summary: Default + Clone + fmt::Debug {
28 type Context;
29
30 fn add_summary(&mut self, summary: &Self, cx: &Self::Context);
31}
32
33pub trait Dimension<'a, S: Summary>: Clone + fmt::Debug + Default {
34 fn add_summary(&mut self, _summary: &'a S, _: &S::Context);
35
36 fn from_summary(summary: &'a S, cx: &S::Context) -> Self {
37 let mut dimension = Self::default();
38 dimension.add_summary(summary, cx);
39 dimension
40 }
41}
42
43impl<'a, T: Summary> Dimension<'a, T> for T {
44 fn add_summary(&mut self, summary: &'a T, cx: &T::Context) {
45 Summary::add_summary(self, summary, cx);
46 }
47}
48
49pub trait SeekTarget<'a, S: Summary, D: Dimension<'a, S>>: fmt::Debug {
50 fn cmp(&self, cursor_location: &D, cx: &S::Context) -> Ordering;
51}
52
53impl<'a, S: Summary, D: Dimension<'a, S> + Ord> SeekTarget<'a, S, D> for D {
54 fn cmp(&self, cursor_location: &Self, _: &S::Context) -> Ordering {
55 Ord::cmp(self, cursor_location)
56 }
57}
58
59impl<'a, T: Summary> Dimension<'a, T> for () {
60 fn add_summary(&mut self, _: &'a T, _: &T::Context) {}
61}
62
63impl<'a, T: Summary, D1: Dimension<'a, T>, D2: Dimension<'a, T>> Dimension<'a, T> for (D1, D2) {
64 fn add_summary(&mut self, summary: &'a T, cx: &T::Context) {
65 self.0.add_summary(summary, cx);
66 self.1.add_summary(summary, cx);
67 }
68}
69
70impl<'a, S: Summary, D1: SeekTarget<'a, S, D1> + Dimension<'a, S>, D2: Dimension<'a, S>>
71 SeekTarget<'a, S, (D1, D2)> for D1
72{
73 fn cmp(&self, cursor_location: &(D1, D2), cx: &S::Context) -> Ordering {
74 self.cmp(&cursor_location.0, cx)
75 }
76}
77
78struct End<D>(PhantomData<D>);
79
80impl<D> End<D> {
81 fn new() -> Self {
82 Self(PhantomData)
83 }
84}
85
86impl<'a, S: Summary, D: Dimension<'a, S>> SeekTarget<'a, S, D> for End<D> {
87 fn cmp(&self, _: &D, _: &S::Context) -> Ordering {
88 Ordering::Greater
89 }
90}
91
92impl<D> fmt::Debug for End<D> {
93 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
94 f.debug_tuple("End").finish()
95 }
96}
97
98#[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Debug, Hash, Default)]
99pub enum Bias {
100 #[default]
101 Left,
102 Right,
103}
104
105#[derive(Debug, Clone)]
106pub struct SumTree<T: Item>(Arc<Node<T>>);
107
108impl<T: Item> SumTree<T> {
109 pub fn new() -> Self {
110 SumTree(Arc::new(Node::Leaf {
111 summary: T::Summary::default(),
112 items: ArrayVec::new(),
113 item_summaries: ArrayVec::new(),
114 }))
115 }
116
117 pub fn from_item(item: T, cx: &<T::Summary as Summary>::Context) -> Self {
118 let mut tree = Self::new();
119 tree.push(item, cx);
120 tree
121 }
122
123 pub fn from_iter<I: IntoIterator<Item = T>>(
124 iter: I,
125 cx: &<T::Summary as Summary>::Context,
126 ) -> Self {
127 let mut tree = Self::new();
128 tree.extend(iter, cx);
129 tree
130 }
131
132 #[allow(unused)]
133 pub fn items(&self, cx: &<T::Summary as Summary>::Context) -> Vec<T> {
134 let mut items = Vec::new();
135 let mut cursor = self.cursor::<()>();
136 cursor.next(cx);
137 while let Some(item) = cursor.item() {
138 items.push(item.clone());
139 cursor.next(cx);
140 }
141 items
142 }
143
144 pub fn iter(&self) -> Iter<T> {
145 Iter::new(self)
146 }
147
148 pub fn cursor<'a, S>(&'a self) -> Cursor<T, S>
149 where
150 S: Dimension<'a, T::Summary>,
151 {
152 Cursor::new(self)
153 }
154
155 /// Note: If the summary type requires a non `()` context, then the filter cursor
156 /// that is returned cannot be used with Rust's iterators.
157 pub fn filter<'a, F, U>(&'a self, filter_node: F) -> FilterCursor<F, T, U>
158 where
159 F: FnMut(&T::Summary) -> bool,
160 U: Dimension<'a, T::Summary>,
161 {
162 FilterCursor::new(self, filter_node)
163 }
164
165 #[allow(dead_code)]
166 pub fn first(&self) -> Option<&T> {
167 self.leftmost_leaf().0.items().first()
168 }
169
170 pub fn last(&self) -> Option<&T> {
171 self.rightmost_leaf().0.items().last()
172 }
173
174 pub fn update_last(&mut self, f: impl FnOnce(&mut T), cx: &<T::Summary as Summary>::Context) {
175 self.update_last_recursive(f, cx);
176 }
177
178 fn update_last_recursive(
179 &mut self,
180 f: impl FnOnce(&mut T),
181 cx: &<T::Summary as Summary>::Context,
182 ) -> Option<T::Summary> {
183 match Arc::make_mut(&mut self.0) {
184 Node::Internal {
185 summary,
186 child_summaries,
187 child_trees,
188 ..
189 } => {
190 let last_summary = child_summaries.last_mut().unwrap();
191 let last_child = child_trees.last_mut().unwrap();
192 *last_summary = last_child.update_last_recursive(f, cx).unwrap();
193 *summary = sum(child_summaries.iter(), cx);
194 Some(summary.clone())
195 }
196 Node::Leaf {
197 summary,
198 items,
199 item_summaries,
200 } => {
201 if let Some((item, item_summary)) = items.last_mut().zip(item_summaries.last_mut())
202 {
203 (f)(item);
204 *item_summary = item.summary();
205 *summary = sum(item_summaries.iter(), cx);
206 Some(summary.clone())
207 } else {
208 None
209 }
210 }
211 }
212 }
213
214 pub fn extent<'a, D: Dimension<'a, T::Summary>>(
215 &'a self,
216 cx: &<T::Summary as Summary>::Context,
217 ) -> D {
218 let mut extent = D::default();
219 match self.0.as_ref() {
220 Node::Internal { summary, .. } | Node::Leaf { summary, .. } => {
221 extent.add_summary(summary, cx);
222 }
223 }
224 extent
225 }
226
227 pub fn summary(&self) -> &T::Summary {
228 match self.0.as_ref() {
229 Node::Internal { summary, .. } => summary,
230 Node::Leaf { summary, .. } => summary,
231 }
232 }
233
234 pub fn is_empty(&self) -> bool {
235 match self.0.as_ref() {
236 Node::Internal { .. } => false,
237 Node::Leaf { items, .. } => items.is_empty(),
238 }
239 }
240
241 pub fn extend<I>(&mut self, iter: I, cx: &<T::Summary as Summary>::Context)
242 where
243 I: IntoIterator<Item = T>,
244 {
245 let mut leaf: Option<Node<T>> = None;
246
247 for item in iter {
248 if leaf.is_some() && leaf.as_ref().unwrap().items().len() == 2 * TREE_BASE {
249 self.append(SumTree(Arc::new(leaf.take().unwrap())), cx);
250 }
251
252 if leaf.is_none() {
253 leaf = Some(Node::Leaf::<T> {
254 summary: T::Summary::default(),
255 items: ArrayVec::new(),
256 item_summaries: ArrayVec::new(),
257 });
258 }
259
260 if let Some(Node::Leaf {
261 summary,
262 items,
263 item_summaries,
264 }) = leaf.as_mut()
265 {
266 let item_summary = item.summary();
267 <T::Summary as Summary>::add_summary(summary, &item_summary, cx);
268 items.push(item);
269 item_summaries.push(item_summary);
270 } else {
271 unreachable!()
272 }
273 }
274
275 if leaf.is_some() {
276 self.append(SumTree(Arc::new(leaf.take().unwrap())), cx);
277 }
278 }
279
280 pub fn push(&mut self, item: T, cx: &<T::Summary as Summary>::Context) {
281 let summary = item.summary();
282 self.append(
283 SumTree(Arc::new(Node::Leaf {
284 summary: summary.clone(),
285 items: ArrayVec::from_iter(Some(item)),
286 item_summaries: ArrayVec::from_iter(Some(summary)),
287 })),
288 cx,
289 );
290 }
291
292 pub fn append(&mut self, other: Self, cx: &<T::Summary as Summary>::Context) {
293 if !other.0.is_leaf() || !other.0.items().is_empty() {
294 if self.0.height() < other.0.height() {
295 for tree in other.0.child_trees() {
296 self.append(tree.clone(), cx);
297 }
298 } else if let Some(split_tree) = self.push_tree_recursive(other, cx) {
299 *self = Self::from_child_trees(self.clone(), split_tree, cx);
300 }
301 }
302 }
303
304 fn push_tree_recursive(
305 &mut self,
306 other: SumTree<T>,
307 cx: &<T::Summary as Summary>::Context,
308 ) -> Option<SumTree<T>> {
309 match Arc::make_mut(&mut self.0) {
310 Node::Internal {
311 height,
312 summary,
313 child_summaries,
314 child_trees,
315 ..
316 } => {
317 let other_node = other.0.clone();
318 <T::Summary as Summary>::add_summary(summary, other_node.summary(), cx);
319
320 let height_delta = *height - other_node.height();
321 let mut summaries_to_append = ArrayVec::<T::Summary, { 2 * TREE_BASE }>::new();
322 let mut trees_to_append = ArrayVec::<SumTree<T>, { 2 * TREE_BASE }>::new();
323 if height_delta == 0 {
324 summaries_to_append.extend(other_node.child_summaries().iter().cloned());
325 trees_to_append.extend(other_node.child_trees().iter().cloned());
326 } else if height_delta == 1 && !other_node.is_underflowing() {
327 summaries_to_append.push(other_node.summary().clone());
328 trees_to_append.push(other)
329 } else {
330 let tree_to_append = child_trees
331 .last_mut()
332 .unwrap()
333 .push_tree_recursive(other, cx);
334 *child_summaries.last_mut().unwrap() =
335 child_trees.last().unwrap().0.summary().clone();
336
337 if let Some(split_tree) = tree_to_append {
338 summaries_to_append.push(split_tree.0.summary().clone());
339 trees_to_append.push(split_tree);
340 }
341 }
342
343 let child_count = child_trees.len() + trees_to_append.len();
344 if child_count > 2 * TREE_BASE {
345 let left_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
346 let right_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
347 let left_trees;
348 let right_trees;
349
350 let midpoint = (child_count + child_count % 2) / 2;
351 {
352 let mut all_summaries = child_summaries
353 .iter()
354 .chain(summaries_to_append.iter())
355 .cloned();
356 left_summaries = all_summaries.by_ref().take(midpoint).collect();
357 right_summaries = all_summaries.collect();
358 let mut all_trees =
359 child_trees.iter().chain(trees_to_append.iter()).cloned();
360 left_trees = all_trees.by_ref().take(midpoint).collect();
361 right_trees = all_trees.collect();
362 }
363 *summary = sum(left_summaries.iter(), cx);
364 *child_summaries = left_summaries;
365 *child_trees = left_trees;
366
367 Some(SumTree(Arc::new(Node::Internal {
368 height: *height,
369 summary: sum(right_summaries.iter(), cx),
370 child_summaries: right_summaries,
371 child_trees: right_trees,
372 })))
373 } else {
374 child_summaries.extend(summaries_to_append);
375 child_trees.extend(trees_to_append);
376 None
377 }
378 }
379 Node::Leaf {
380 summary,
381 items,
382 item_summaries,
383 } => {
384 let other_node = other.0;
385
386 let child_count = items.len() + other_node.items().len();
387 if child_count > 2 * TREE_BASE {
388 let left_items;
389 let right_items;
390 let left_summaries;
391 let right_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>;
392
393 let midpoint = (child_count + child_count % 2) / 2;
394 {
395 let mut all_items = items.iter().chain(other_node.items().iter()).cloned();
396 left_items = all_items.by_ref().take(midpoint).collect();
397 right_items = all_items.collect();
398
399 let mut all_summaries = item_summaries
400 .iter()
401 .chain(other_node.child_summaries())
402 .cloned();
403 left_summaries = all_summaries.by_ref().take(midpoint).collect();
404 right_summaries = all_summaries.collect();
405 }
406 *items = left_items;
407 *item_summaries = left_summaries;
408 *summary = sum(item_summaries.iter(), cx);
409 Some(SumTree(Arc::new(Node::Leaf {
410 items: right_items,
411 summary: sum(right_summaries.iter(), cx),
412 item_summaries: right_summaries,
413 })))
414 } else {
415 <T::Summary as Summary>::add_summary(summary, other_node.summary(), cx);
416 items.extend(other_node.items().iter().cloned());
417 item_summaries.extend(other_node.child_summaries().iter().cloned());
418 None
419 }
420 }
421 }
422 }
423
424 fn from_child_trees(
425 left: SumTree<T>,
426 right: SumTree<T>,
427 cx: &<T::Summary as Summary>::Context,
428 ) -> Self {
429 let height = left.0.height() + 1;
430 let mut child_summaries = ArrayVec::new();
431 child_summaries.push(left.0.summary().clone());
432 child_summaries.push(right.0.summary().clone());
433 let mut child_trees = ArrayVec::new();
434 child_trees.push(left);
435 child_trees.push(right);
436 SumTree(Arc::new(Node::Internal {
437 height,
438 summary: sum(child_summaries.iter(), cx),
439 child_summaries,
440 child_trees,
441 }))
442 }
443
444 fn leftmost_leaf(&self) -> &Self {
445 match *self.0 {
446 Node::Leaf { .. } => self,
447 Node::Internal {
448 ref child_trees, ..
449 } => child_trees.first().unwrap().leftmost_leaf(),
450 }
451 }
452
453 fn rightmost_leaf(&self) -> &Self {
454 match *self.0 {
455 Node::Leaf { .. } => self,
456 Node::Internal {
457 ref child_trees, ..
458 } => child_trees.last().unwrap().rightmost_leaf(),
459 }
460 }
461
462 #[cfg(debug_assertions)]
463 pub fn _debug_entries(&self) -> Vec<&T> {
464 self.iter().collect::<Vec<_>>()
465 }
466}
467
468impl<T: Item + PartialEq> PartialEq for SumTree<T> {
469 fn eq(&self, other: &Self) -> bool {
470 self.iter().eq(other.iter())
471 }
472}
473
474impl<T: Item + Eq> Eq for SumTree<T> {}
475
476impl<T: KeyedItem> SumTree<T> {
477 pub fn insert_or_replace(
478 &mut self,
479 item: T,
480 cx: &<T::Summary as Summary>::Context,
481 ) -> Option<T> {
482 let mut replaced = None;
483 *self = {
484 let mut cursor = self.cursor::<T::Key>();
485 let mut new_tree = cursor.slice(&item.key(), Bias::Left, cx);
486 if let Some(cursor_item) = cursor.item() {
487 if cursor_item.key() == item.key() {
488 replaced = Some(cursor_item.clone());
489 cursor.next(cx);
490 }
491 }
492 new_tree.push(item, cx);
493 new_tree.append(cursor.suffix(cx), cx);
494 new_tree
495 };
496 replaced
497 }
498
499 pub fn remove(&mut self, key: &T::Key, cx: &<T::Summary as Summary>::Context) -> Option<T> {
500 let mut removed = None;
501 *self = {
502 let mut cursor = self.cursor::<T::Key>();
503 let mut new_tree = cursor.slice(key, Bias::Left, cx);
504 if let Some(item) = cursor.item() {
505 if item.key() == *key {
506 removed = Some(item.clone());
507 cursor.next(cx);
508 }
509 }
510 new_tree.append(cursor.suffix(cx), cx);
511 new_tree
512 };
513 removed
514 }
515
516 pub fn edit(
517 &mut self,
518 mut edits: Vec<Edit<T>>,
519 cx: &<T::Summary as Summary>::Context,
520 ) -> Vec<T> {
521 if edits.is_empty() {
522 return Vec::new();
523 }
524
525 let mut removed = Vec::new();
526 edits.sort_unstable_by_key(|item| item.key());
527
528 *self = {
529 let mut cursor = self.cursor::<T::Key>();
530 let mut new_tree = SumTree::new();
531 let mut buffered_items = Vec::new();
532
533 cursor.seek(&T::Key::default(), Bias::Left, cx);
534 for edit in edits {
535 let new_key = edit.key();
536 let mut old_item = cursor.item();
537
538 if old_item
539 .as_ref()
540 .map_or(false, |old_item| old_item.key() < new_key)
541 {
542 new_tree.extend(buffered_items.drain(..), cx);
543 let slice = cursor.slice(&new_key, Bias::Left, cx);
544 new_tree.append(slice, cx);
545 old_item = cursor.item();
546 }
547
548 if let Some(old_item) = old_item {
549 if old_item.key() == new_key {
550 removed.push(old_item.clone());
551 cursor.next(cx);
552 }
553 }
554
555 match edit {
556 Edit::Insert(item) => {
557 buffered_items.push(item);
558 }
559 Edit::Remove(_) => {}
560 }
561 }
562
563 new_tree.extend(buffered_items, cx);
564 new_tree.append(cursor.suffix(cx), cx);
565 new_tree
566 };
567
568 removed
569 }
570
571 pub fn get(&self, key: &T::Key, cx: &<T::Summary as Summary>::Context) -> Option<&T> {
572 let mut cursor = self.cursor::<T::Key>();
573 if cursor.seek(key, Bias::Left, cx) {
574 cursor.item()
575 } else {
576 None
577 }
578 }
579}
580
581impl<T: Item> Default for SumTree<T> {
582 fn default() -> Self {
583 Self::new()
584 }
585}
586
587#[derive(Clone, Debug)]
588pub enum Node<T: Item> {
589 Internal {
590 height: u8,
591 summary: T::Summary,
592 child_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
593 child_trees: ArrayVec<SumTree<T>, { 2 * TREE_BASE }>,
594 },
595 Leaf {
596 summary: T::Summary,
597 items: ArrayVec<T, { 2 * TREE_BASE }>,
598 item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
599 },
600}
601
602impl<T: Item> Node<T> {
603 fn is_leaf(&self) -> bool {
604 matches!(self, Node::Leaf { .. })
605 }
606
607 fn height(&self) -> u8 {
608 match self {
609 Node::Internal { height, .. } => *height,
610 Node::Leaf { .. } => 0,
611 }
612 }
613
614 fn summary(&self) -> &T::Summary {
615 match self {
616 Node::Internal { summary, .. } => summary,
617 Node::Leaf { summary, .. } => summary,
618 }
619 }
620
621 fn child_summaries(&self) -> &[T::Summary] {
622 match self {
623 Node::Internal {
624 child_summaries, ..
625 } => child_summaries.as_slice(),
626 Node::Leaf { item_summaries, .. } => item_summaries.as_slice(),
627 }
628 }
629
630 fn child_trees(&self) -> &ArrayVec<SumTree<T>, { 2 * TREE_BASE }> {
631 match self {
632 Node::Internal { child_trees, .. } => child_trees,
633 Node::Leaf { .. } => panic!("Leaf nodes have no child trees"),
634 }
635 }
636
637 fn items(&self) -> &ArrayVec<T, { 2 * TREE_BASE }> {
638 match self {
639 Node::Leaf { items, .. } => items,
640 Node::Internal { .. } => panic!("Internal nodes have no items"),
641 }
642 }
643
644 fn is_underflowing(&self) -> bool {
645 match self {
646 Node::Internal { child_trees, .. } => child_trees.len() < TREE_BASE,
647 Node::Leaf { items, .. } => items.len() < TREE_BASE,
648 }
649 }
650}
651
652#[derive(Debug)]
653pub enum Edit<T: KeyedItem> {
654 Insert(T),
655 Remove(T::Key),
656}
657
658impl<T: KeyedItem> Edit<T> {
659 fn key(&self) -> T::Key {
660 match self {
661 Edit::Insert(item) => item.key(),
662 Edit::Remove(key) => key.clone(),
663 }
664 }
665}
666
667fn sum<'a, T, I>(iter: I, cx: &T::Context) -> T
668where
669 T: 'a + Summary,
670 I: Iterator<Item = &'a T>,
671{
672 let mut sum = T::default();
673 for value in iter {
674 sum.add_summary(value, cx);
675 }
676 sum
677}
678
679#[cfg(test)]
680mod tests {
681 use super::*;
682 use rand::{distributions, prelude::*};
683 use std::cmp;
684
685 #[ctor::ctor]
686 fn init_logger() {
687 if std::env::var("RUST_LOG").is_ok() {
688 env_logger::init();
689 }
690 }
691
692 #[test]
693 fn test_extend_and_push_tree() {
694 let mut tree1 = SumTree::new();
695 tree1.extend(0..20, &());
696
697 let mut tree2 = SumTree::new();
698 tree2.extend(50..100, &());
699
700 tree1.append(tree2, &());
701 assert_eq!(
702 tree1.items(&()),
703 (0..20).chain(50..100).collect::<Vec<u8>>()
704 );
705 }
706
707 #[test]
708 fn test_random() {
709 let mut starting_seed = 0;
710 if let Ok(value) = std::env::var("SEED") {
711 starting_seed = value.parse().expect("invalid SEED variable");
712 }
713 let mut num_iterations = 100;
714 if let Ok(value) = std::env::var("ITERATIONS") {
715 num_iterations = value.parse().expect("invalid ITERATIONS variable");
716 }
717 let num_operations = std::env::var("OPERATIONS")
718 .map_or(5, |o| o.parse().expect("invalid OPERATIONS variable"));
719
720 for seed in starting_seed..(starting_seed + num_iterations) {
721 eprintln!("seed = {}", seed);
722 let mut rng = StdRng::seed_from_u64(seed);
723
724 let rng = &mut rng;
725 let mut tree = SumTree::<u8>::new();
726 let count = rng.gen_range(0..10);
727 tree.extend(rng.sample_iter(distributions::Standard).take(count), &());
728
729 for _ in 0..num_operations {
730 let splice_end = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
731 let splice_start = rng.gen_range(0..splice_end + 1);
732 let count = rng.gen_range(0..3);
733 let tree_end = tree.extent::<Count>(&());
734 let new_items = rng
735 .sample_iter(distributions::Standard)
736 .take(count)
737 .collect::<Vec<u8>>();
738
739 let mut reference_items = tree.items(&());
740 reference_items.splice(splice_start..splice_end, new_items.clone());
741
742 tree = {
743 let mut cursor = tree.cursor::<Count>();
744 let mut new_tree = cursor.slice(&Count(splice_start), Bias::Right, &());
745 new_tree.extend(new_items, &());
746 cursor.seek(&Count(splice_end), Bias::Right, &());
747 new_tree.append(cursor.slice(&tree_end, Bias::Right, &()), &());
748 new_tree
749 };
750
751 assert_eq!(tree.items(&()), reference_items);
752 assert_eq!(
753 tree.iter().collect::<Vec<_>>(),
754 tree.cursor::<()>().collect::<Vec<_>>()
755 );
756
757 log::info!("tree items: {:?}", tree.items(&()));
758
759 let mut filter_cursor = tree.filter::<_, Count>(|summary| summary.contains_even);
760 let expected_filtered_items = tree
761 .items(&())
762 .into_iter()
763 .enumerate()
764 .filter(|(_, item)| (item & 1) == 0)
765 .collect::<Vec<_>>();
766
767 let mut item_ix = if rng.gen() {
768 filter_cursor.next(&());
769 0
770 } else {
771 filter_cursor.prev(&());
772 expected_filtered_items.len().saturating_sub(1)
773 };
774 while item_ix < expected_filtered_items.len() {
775 log::info!("filter_cursor, item_ix: {}", item_ix);
776 let actual_item = filter_cursor.item().unwrap();
777 let (reference_index, reference_item) = expected_filtered_items[item_ix];
778 assert_eq!(actual_item, &reference_item);
779 assert_eq!(filter_cursor.start().0, reference_index);
780 log::info!("next");
781 filter_cursor.next(&());
782 item_ix += 1;
783
784 while item_ix > 0 && rng.gen_bool(0.2) {
785 log::info!("prev");
786 filter_cursor.prev(&());
787 item_ix -= 1;
788
789 if item_ix == 0 && rng.gen_bool(0.2) {
790 filter_cursor.prev(&());
791 assert_eq!(filter_cursor.item(), None);
792 assert_eq!(filter_cursor.start().0, 0);
793 filter_cursor.next(&());
794 }
795 }
796 }
797 assert_eq!(filter_cursor.item(), None);
798
799 let mut pos = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
800 let mut before_start = false;
801 let mut cursor = tree.cursor::<Count>();
802 cursor.seek(&Count(pos), Bias::Right, &());
803
804 for i in 0..10 {
805 assert_eq!(cursor.start().0, pos);
806
807 if pos > 0 {
808 assert_eq!(cursor.prev_item().unwrap(), &reference_items[pos - 1]);
809 } else {
810 assert_eq!(cursor.prev_item(), None);
811 }
812
813 if pos < reference_items.len() && !before_start {
814 assert_eq!(cursor.item().unwrap(), &reference_items[pos]);
815 } else {
816 assert_eq!(cursor.item(), None);
817 }
818
819 if i < 5 {
820 cursor.next(&());
821 if pos < reference_items.len() {
822 pos += 1;
823 before_start = false;
824 }
825 } else {
826 cursor.prev(&());
827 if pos == 0 {
828 before_start = true;
829 }
830 pos = pos.saturating_sub(1);
831 }
832 }
833 }
834
835 for _ in 0..10 {
836 let end = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
837 let start = rng.gen_range(0..end + 1);
838 let start_bias = if rng.gen() { Bias::Left } else { Bias::Right };
839 let end_bias = if rng.gen() { Bias::Left } else { Bias::Right };
840
841 let mut cursor = tree.cursor::<Count>();
842 cursor.seek(&Count(start), start_bias, &());
843 let slice = cursor.slice(&Count(end), end_bias, &());
844
845 cursor.seek(&Count(start), start_bias, &());
846 let summary = cursor.summary::<_, Sum>(&Count(end), end_bias, &());
847
848 assert_eq!(summary.0, slice.summary().sum);
849 }
850 }
851 }
852
853 #[test]
854 fn test_cursor() {
855 // Empty tree
856 let tree = SumTree::<u8>::new();
857 let mut cursor = tree.cursor::<IntegersSummary>();
858 assert_eq!(
859 cursor.slice(&Count(0), Bias::Right, &()).items(&()),
860 Vec::<u8>::new()
861 );
862 assert_eq!(cursor.item(), None);
863 assert_eq!(cursor.prev_item(), None);
864 assert_eq!(cursor.start().sum, 0);
865 cursor.prev(&());
866 assert_eq!(cursor.item(), None);
867 assert_eq!(cursor.prev_item(), None);
868 assert_eq!(cursor.start().sum, 0);
869 cursor.next(&());
870 assert_eq!(cursor.item(), None);
871 assert_eq!(cursor.prev_item(), None);
872 assert_eq!(cursor.start().sum, 0);
873
874 // Single-element tree
875 let mut tree = SumTree::<u8>::new();
876 tree.extend(vec![1], &());
877 let mut cursor = tree.cursor::<IntegersSummary>();
878 assert_eq!(
879 cursor.slice(&Count(0), Bias::Right, &()).items(&()),
880 Vec::<u8>::new()
881 );
882 assert_eq!(cursor.item(), Some(&1));
883 assert_eq!(cursor.prev_item(), None);
884 assert_eq!(cursor.start().sum, 0);
885
886 cursor.next(&());
887 assert_eq!(cursor.item(), None);
888 assert_eq!(cursor.prev_item(), Some(&1));
889 assert_eq!(cursor.start().sum, 1);
890
891 cursor.prev(&());
892 assert_eq!(cursor.item(), Some(&1));
893 assert_eq!(cursor.prev_item(), None);
894 assert_eq!(cursor.start().sum, 0);
895
896 let mut cursor = tree.cursor::<IntegersSummary>();
897 assert_eq!(cursor.slice(&Count(1), Bias::Right, &()).items(&()), [1]);
898 assert_eq!(cursor.item(), None);
899 assert_eq!(cursor.prev_item(), Some(&1));
900 assert_eq!(cursor.start().sum, 1);
901
902 cursor.seek(&Count(0), Bias::Right, &());
903 assert_eq!(
904 cursor
905 .slice(&tree.extent::<Count>(&()), Bias::Right, &())
906 .items(&()),
907 [1]
908 );
909 assert_eq!(cursor.item(), None);
910 assert_eq!(cursor.prev_item(), Some(&1));
911 assert_eq!(cursor.start().sum, 1);
912
913 // Multiple-element tree
914 let mut tree = SumTree::new();
915 tree.extend(vec![1, 2, 3, 4, 5, 6], &());
916 let mut cursor = tree.cursor::<IntegersSummary>();
917
918 assert_eq!(cursor.slice(&Count(2), Bias::Right, &()).items(&()), [1, 2]);
919 assert_eq!(cursor.item(), Some(&3));
920 assert_eq!(cursor.prev_item(), Some(&2));
921 assert_eq!(cursor.start().sum, 3);
922
923 cursor.next(&());
924 assert_eq!(cursor.item(), Some(&4));
925 assert_eq!(cursor.prev_item(), Some(&3));
926 assert_eq!(cursor.start().sum, 6);
927
928 cursor.next(&());
929 assert_eq!(cursor.item(), Some(&5));
930 assert_eq!(cursor.prev_item(), Some(&4));
931 assert_eq!(cursor.start().sum, 10);
932
933 cursor.next(&());
934 assert_eq!(cursor.item(), Some(&6));
935 assert_eq!(cursor.prev_item(), Some(&5));
936 assert_eq!(cursor.start().sum, 15);
937
938 cursor.next(&());
939 cursor.next(&());
940 assert_eq!(cursor.item(), None);
941 assert_eq!(cursor.prev_item(), Some(&6));
942 assert_eq!(cursor.start().sum, 21);
943
944 cursor.prev(&());
945 assert_eq!(cursor.item(), Some(&6));
946 assert_eq!(cursor.prev_item(), Some(&5));
947 assert_eq!(cursor.start().sum, 15);
948
949 cursor.prev(&());
950 assert_eq!(cursor.item(), Some(&5));
951 assert_eq!(cursor.prev_item(), Some(&4));
952 assert_eq!(cursor.start().sum, 10);
953
954 cursor.prev(&());
955 assert_eq!(cursor.item(), Some(&4));
956 assert_eq!(cursor.prev_item(), Some(&3));
957 assert_eq!(cursor.start().sum, 6);
958
959 cursor.prev(&());
960 assert_eq!(cursor.item(), Some(&3));
961 assert_eq!(cursor.prev_item(), Some(&2));
962 assert_eq!(cursor.start().sum, 3);
963
964 cursor.prev(&());
965 assert_eq!(cursor.item(), Some(&2));
966 assert_eq!(cursor.prev_item(), Some(&1));
967 assert_eq!(cursor.start().sum, 1);
968
969 cursor.prev(&());
970 assert_eq!(cursor.item(), Some(&1));
971 assert_eq!(cursor.prev_item(), None);
972 assert_eq!(cursor.start().sum, 0);
973
974 cursor.prev(&());
975 assert_eq!(cursor.item(), None);
976 assert_eq!(cursor.prev_item(), None);
977 assert_eq!(cursor.start().sum, 0);
978
979 cursor.next(&());
980 assert_eq!(cursor.item(), Some(&1));
981 assert_eq!(cursor.prev_item(), None);
982 assert_eq!(cursor.start().sum, 0);
983
984 let mut cursor = tree.cursor::<IntegersSummary>();
985 assert_eq!(
986 cursor
987 .slice(&tree.extent::<Count>(&()), Bias::Right, &())
988 .items(&()),
989 tree.items(&())
990 );
991 assert_eq!(cursor.item(), None);
992 assert_eq!(cursor.prev_item(), Some(&6));
993 assert_eq!(cursor.start().sum, 21);
994
995 cursor.seek(&Count(3), Bias::Right, &());
996 assert_eq!(
997 cursor
998 .slice(&tree.extent::<Count>(&()), Bias::Right, &())
999 .items(&()),
1000 [4, 5, 6]
1001 );
1002 assert_eq!(cursor.item(), None);
1003 assert_eq!(cursor.prev_item(), Some(&6));
1004 assert_eq!(cursor.start().sum, 21);
1005
1006 // Seeking can bias left or right
1007 cursor.seek(&Count(1), Bias::Left, &());
1008 assert_eq!(cursor.item(), Some(&1));
1009 cursor.seek(&Count(1), Bias::Right, &());
1010 assert_eq!(cursor.item(), Some(&2));
1011
1012 // Slicing without resetting starts from where the cursor is parked at.
1013 cursor.seek(&Count(1), Bias::Right, &());
1014 assert_eq!(
1015 cursor.slice(&Count(3), Bias::Right, &()).items(&()),
1016 vec![2, 3]
1017 );
1018 assert_eq!(
1019 cursor.slice(&Count(6), Bias::Left, &()).items(&()),
1020 vec![4, 5]
1021 );
1022 assert_eq!(
1023 cursor.slice(&Count(6), Bias::Right, &()).items(&()),
1024 vec![6]
1025 );
1026 }
1027
1028 #[test]
1029 fn test_edit() {
1030 let mut tree = SumTree::<u8>::new();
1031
1032 let removed = tree.edit(vec![Edit::Insert(1), Edit::Insert(2), Edit::Insert(0)], &());
1033 assert_eq!(tree.items(&()), vec![0, 1, 2]);
1034 assert_eq!(removed, Vec::<u8>::new());
1035 assert_eq!(tree.get(&0, &()), Some(&0));
1036 assert_eq!(tree.get(&1, &()), Some(&1));
1037 assert_eq!(tree.get(&2, &()), Some(&2));
1038 assert_eq!(tree.get(&4, &()), None);
1039
1040 let removed = tree.edit(vec![Edit::Insert(2), Edit::Insert(4), Edit::Remove(0)], &());
1041 assert_eq!(tree.items(&()), vec![1, 2, 4]);
1042 assert_eq!(removed, vec![0, 2]);
1043 assert_eq!(tree.get(&0, &()), None);
1044 assert_eq!(tree.get(&1, &()), Some(&1));
1045 assert_eq!(tree.get(&2, &()), Some(&2));
1046 assert_eq!(tree.get(&4, &()), Some(&4));
1047 }
1048
1049 #[derive(Clone, Default, Debug)]
1050 pub struct IntegersSummary {
1051 count: usize,
1052 sum: usize,
1053 contains_even: bool,
1054 max: u8,
1055 }
1056
1057 #[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
1058 struct Count(usize);
1059
1060 #[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
1061 struct Sum(usize);
1062
1063 impl Item for u8 {
1064 type Summary = IntegersSummary;
1065
1066 fn summary(&self) -> Self::Summary {
1067 IntegersSummary {
1068 count: 1,
1069 sum: *self as usize,
1070 contains_even: (*self & 1) == 0,
1071 max: *self,
1072 }
1073 }
1074 }
1075
1076 impl KeyedItem for u8 {
1077 type Key = u8;
1078
1079 fn key(&self) -> Self::Key {
1080 *self
1081 }
1082 }
1083
1084 impl Summary for IntegersSummary {
1085 type Context = ();
1086
1087 fn add_summary(&mut self, other: &Self, _: &()) {
1088 self.count += other.count;
1089 self.sum += other.sum;
1090 self.contains_even |= other.contains_even;
1091 self.max = cmp::max(self.max, other.max);
1092 }
1093 }
1094
1095 impl<'a> Dimension<'a, IntegersSummary> for u8 {
1096 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1097 *self = summary.max;
1098 }
1099 }
1100
1101 impl<'a> Dimension<'a, IntegersSummary> for Count {
1102 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1103 self.0 += summary.count;
1104 }
1105 }
1106
1107 impl<'a> SeekTarget<'a, IntegersSummary, IntegersSummary> for Count {
1108 fn cmp(&self, cursor_location: &IntegersSummary, _: &()) -> Ordering {
1109 self.0.cmp(&cursor_location.count)
1110 }
1111 }
1112
1113 impl<'a> Dimension<'a, IntegersSummary> for Sum {
1114 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1115 self.0 += summary.sum;
1116 }
1117 }
1118}