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, Debug, Hash)]
99pub enum Bias {
100 Left,
101 Right,
102}
103
104impl Default for Bias {
105 fn default() -> Self {
106 Bias::Left
107 }
108}
109
110impl PartialOrd for Bias {
111 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
112 Some(self.cmp(other))
113 }
114}
115
116impl Ord for Bias {
117 fn cmp(&self, other: &Self) -> Ordering {
118 match (self, other) {
119 (Self::Left, Self::Left) => Ordering::Equal,
120 (Self::Left, Self::Right) => Ordering::Less,
121 (Self::Right, Self::Right) => Ordering::Equal,
122 (Self::Right, Self::Left) => Ordering::Greater,
123 }
124 }
125}
126
127#[derive(Debug, Clone)]
128pub struct SumTree<T: Item>(Arc<Node<T>>);
129
130impl<T: Item> SumTree<T> {
131 pub fn new() -> Self {
132 SumTree(Arc::new(Node::Leaf {
133 summary: T::Summary::default(),
134 items: ArrayVec::new(),
135 item_summaries: ArrayVec::new(),
136 }))
137 }
138
139 pub fn from_item(item: T, cx: &<T::Summary as Summary>::Context) -> Self {
140 let mut tree = Self::new();
141 tree.push(item, cx);
142 tree
143 }
144
145 pub fn from_iter<I: IntoIterator<Item = T>>(
146 iter: I,
147 cx: &<T::Summary as Summary>::Context,
148 ) -> Self {
149 let mut tree = Self::new();
150 tree.extend(iter, cx);
151 tree
152 }
153
154 #[allow(unused)]
155 pub fn items(&self, cx: &<T::Summary as Summary>::Context) -> Vec<T> {
156 let mut items = Vec::new();
157 let mut cursor = self.cursor::<()>();
158 cursor.next(cx);
159 while let Some(item) = cursor.item() {
160 items.push(item.clone());
161 cursor.next(cx);
162 }
163 items
164 }
165
166 pub fn iter(&self) -> Iter<T> {
167 Iter::new(self)
168 }
169
170 pub fn cursor<'a, S>(&'a self) -> Cursor<T, S>
171 where
172 S: Dimension<'a, T::Summary>,
173 {
174 Cursor::new(self)
175 }
176
177 /// Note: If the summary type requires a non `()` context, then the filter cursor
178 /// that is returned cannot be used with Rust's iterators.
179 pub fn filter<'a, F, U>(&'a self, filter_node: F) -> FilterCursor<F, T, U>
180 where
181 F: FnMut(&T::Summary) -> bool,
182 U: Dimension<'a, T::Summary>,
183 {
184 FilterCursor::new(self, filter_node)
185 }
186
187 #[allow(dead_code)]
188 pub fn first(&self) -> Option<&T> {
189 self.leftmost_leaf().0.items().first()
190 }
191
192 pub fn last(&self) -> Option<&T> {
193 self.rightmost_leaf().0.items().last()
194 }
195
196 pub fn update_last(&mut self, f: impl FnOnce(&mut T), cx: &<T::Summary as Summary>::Context) {
197 self.update_last_recursive(f, cx);
198 }
199
200 fn update_last_recursive(
201 &mut self,
202 f: impl FnOnce(&mut T),
203 cx: &<T::Summary as Summary>::Context,
204 ) -> Option<T::Summary> {
205 match Arc::make_mut(&mut self.0) {
206 Node::Internal {
207 summary,
208 child_summaries,
209 child_trees,
210 ..
211 } => {
212 let last_summary = child_summaries.last_mut().unwrap();
213 let last_child = child_trees.last_mut().unwrap();
214 *last_summary = last_child.update_last_recursive(f, cx).unwrap();
215 *summary = sum(child_summaries.iter(), cx);
216 Some(summary.clone())
217 }
218 Node::Leaf {
219 summary,
220 items,
221 item_summaries,
222 } => {
223 if let Some((item, item_summary)) = items.last_mut().zip(item_summaries.last_mut())
224 {
225 (f)(item);
226 *item_summary = item.summary();
227 *summary = sum(item_summaries.iter(), cx);
228 Some(summary.clone())
229 } else {
230 None
231 }
232 }
233 }
234 }
235
236 pub fn extent<'a, D: Dimension<'a, T::Summary>>(
237 &'a self,
238 cx: &<T::Summary as Summary>::Context,
239 ) -> D {
240 let mut extent = D::default();
241 match self.0.as_ref() {
242 Node::Internal { summary, .. } | Node::Leaf { summary, .. } => {
243 extent.add_summary(summary, cx);
244 }
245 }
246 extent
247 }
248
249 pub fn summary(&self) -> &T::Summary {
250 match self.0.as_ref() {
251 Node::Internal { summary, .. } => summary,
252 Node::Leaf { summary, .. } => summary,
253 }
254 }
255
256 pub fn is_empty(&self) -> bool {
257 match self.0.as_ref() {
258 Node::Internal { .. } => false,
259 Node::Leaf { items, .. } => items.is_empty(),
260 }
261 }
262
263 pub fn extend<I>(&mut self, iter: I, cx: &<T::Summary as Summary>::Context)
264 where
265 I: IntoIterator<Item = T>,
266 {
267 let mut leaf: Option<Node<T>> = None;
268
269 for item in iter {
270 if leaf.is_some() && leaf.as_ref().unwrap().items().len() == 2 * TREE_BASE {
271 self.push_tree(SumTree(Arc::new(leaf.take().unwrap())), cx);
272 }
273
274 if leaf.is_none() {
275 leaf = Some(Node::Leaf::<T> {
276 summary: T::Summary::default(),
277 items: ArrayVec::new(),
278 item_summaries: ArrayVec::new(),
279 });
280 }
281
282 if let Some(Node::Leaf {
283 summary,
284 items,
285 item_summaries,
286 }) = leaf.as_mut()
287 {
288 let item_summary = item.summary();
289 <T::Summary as Summary>::add_summary(summary, &item_summary, cx);
290 items.push(item);
291 item_summaries.push(item_summary);
292 } else {
293 unreachable!()
294 }
295 }
296
297 if leaf.is_some() {
298 self.push_tree(SumTree(Arc::new(leaf.take().unwrap())), cx);
299 }
300 }
301
302 pub fn push(&mut self, item: T, cx: &<T::Summary as Summary>::Context) {
303 let summary = item.summary();
304 self.push_tree(
305 SumTree(Arc::new(Node::Leaf {
306 summary: summary.clone(),
307 items: ArrayVec::from_iter(Some(item)),
308 item_summaries: ArrayVec::from_iter(Some(summary)),
309 })),
310 cx,
311 );
312 }
313
314 pub fn push_tree(&mut self, other: Self, cx: &<T::Summary as Summary>::Context) {
315 if !other.0.is_leaf() || !other.0.items().is_empty() {
316 if self.0.height() < other.0.height() {
317 for tree in other.0.child_trees() {
318 self.push_tree(tree.clone(), cx);
319 }
320 } else if let Some(split_tree) = self.push_tree_recursive(other, cx) {
321 *self = Self::from_child_trees(self.clone(), split_tree, cx);
322 }
323 }
324 }
325
326 fn push_tree_recursive(
327 &mut self,
328 other: SumTree<T>,
329 cx: &<T::Summary as Summary>::Context,
330 ) -> Option<SumTree<T>> {
331 match Arc::make_mut(&mut self.0) {
332 Node::Internal {
333 height,
334 summary,
335 child_summaries,
336 child_trees,
337 ..
338 } => {
339 let other_node = other.0.clone();
340 <T::Summary as Summary>::add_summary(summary, other_node.summary(), cx);
341
342 let height_delta = *height - other_node.height();
343 let mut summaries_to_append = ArrayVec::<T::Summary, { 2 * TREE_BASE }>::new();
344 let mut trees_to_append = ArrayVec::<SumTree<T>, { 2 * TREE_BASE }>::new();
345 if height_delta == 0 {
346 summaries_to_append.extend(other_node.child_summaries().iter().cloned());
347 trees_to_append.extend(other_node.child_trees().iter().cloned());
348 } else if height_delta == 1 && !other_node.is_underflowing() {
349 summaries_to_append.push(other_node.summary().clone());
350 trees_to_append.push(other)
351 } else {
352 let tree_to_append = child_trees
353 .last_mut()
354 .unwrap()
355 .push_tree_recursive(other, cx);
356 *child_summaries.last_mut().unwrap() =
357 child_trees.last().unwrap().0.summary().clone();
358
359 if let Some(split_tree) = tree_to_append {
360 summaries_to_append.push(split_tree.0.summary().clone());
361 trees_to_append.push(split_tree);
362 }
363 }
364
365 let child_count = child_trees.len() + trees_to_append.len();
366 if child_count > 2 * TREE_BASE {
367 let left_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
368 let right_summaries: ArrayVec<_, { 2 * TREE_BASE }>;
369 let left_trees;
370 let right_trees;
371
372 let midpoint = (child_count + child_count % 2) / 2;
373 {
374 let mut all_summaries = child_summaries
375 .iter()
376 .chain(summaries_to_append.iter())
377 .cloned();
378 left_summaries = all_summaries.by_ref().take(midpoint).collect();
379 right_summaries = all_summaries.collect();
380 let mut all_trees =
381 child_trees.iter().chain(trees_to_append.iter()).cloned();
382 left_trees = all_trees.by_ref().take(midpoint).collect();
383 right_trees = all_trees.collect();
384 }
385 *summary = sum(left_summaries.iter(), cx);
386 *child_summaries = left_summaries;
387 *child_trees = left_trees;
388
389 Some(SumTree(Arc::new(Node::Internal {
390 height: *height,
391 summary: sum(right_summaries.iter(), cx),
392 child_summaries: right_summaries,
393 child_trees: right_trees,
394 })))
395 } else {
396 child_summaries.extend(summaries_to_append);
397 child_trees.extend(trees_to_append);
398 None
399 }
400 }
401 Node::Leaf {
402 summary,
403 items,
404 item_summaries,
405 } => {
406 let other_node = other.0;
407
408 let child_count = items.len() + other_node.items().len();
409 if child_count > 2 * TREE_BASE {
410 let left_items;
411 let right_items;
412 let left_summaries;
413 let right_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>;
414
415 let midpoint = (child_count + child_count % 2) / 2;
416 {
417 let mut all_items = items.iter().chain(other_node.items().iter()).cloned();
418 left_items = all_items.by_ref().take(midpoint).collect();
419 right_items = all_items.collect();
420
421 let mut all_summaries = item_summaries
422 .iter()
423 .chain(other_node.child_summaries())
424 .cloned();
425 left_summaries = all_summaries.by_ref().take(midpoint).collect();
426 right_summaries = all_summaries.collect();
427 }
428 *items = left_items;
429 *item_summaries = left_summaries;
430 *summary = sum(item_summaries.iter(), cx);
431 Some(SumTree(Arc::new(Node::Leaf {
432 items: right_items,
433 summary: sum(right_summaries.iter(), cx),
434 item_summaries: right_summaries,
435 })))
436 } else {
437 <T::Summary as Summary>::add_summary(summary, other_node.summary(), cx);
438 items.extend(other_node.items().iter().cloned());
439 item_summaries.extend(other_node.child_summaries().iter().cloned());
440 None
441 }
442 }
443 }
444 }
445
446 fn from_child_trees(
447 left: SumTree<T>,
448 right: SumTree<T>,
449 cx: &<T::Summary as Summary>::Context,
450 ) -> Self {
451 let height = left.0.height() + 1;
452 let mut child_summaries = ArrayVec::new();
453 child_summaries.push(left.0.summary().clone());
454 child_summaries.push(right.0.summary().clone());
455 let mut child_trees = ArrayVec::new();
456 child_trees.push(left);
457 child_trees.push(right);
458 SumTree(Arc::new(Node::Internal {
459 height,
460 summary: sum(child_summaries.iter(), cx),
461 child_summaries,
462 child_trees,
463 }))
464 }
465
466 fn leftmost_leaf(&self) -> &Self {
467 match *self.0 {
468 Node::Leaf { .. } => self,
469 Node::Internal {
470 ref child_trees, ..
471 } => child_trees.first().unwrap().leftmost_leaf(),
472 }
473 }
474
475 fn rightmost_leaf(&self) -> &Self {
476 match *self.0 {
477 Node::Leaf { .. } => self,
478 Node::Internal {
479 ref child_trees, ..
480 } => child_trees.last().unwrap().rightmost_leaf(),
481 }
482 }
483}
484
485impl<T: Item + PartialEq> PartialEq for SumTree<T> {
486 fn eq(&self, other: &Self) -> bool {
487 self.iter().eq(other.iter())
488 }
489}
490
491impl<T: Item + Eq> Eq for SumTree<T> {}
492
493impl<T: KeyedItem> SumTree<T> {
494 pub fn insert_or_replace(
495 &mut self,
496 item: T,
497 cx: &<T::Summary as Summary>::Context,
498 ) -> Option<T> {
499 let mut replaced = None;
500 *self = {
501 let mut cursor = self.cursor::<T::Key>();
502 let mut new_tree = cursor.slice(&item.key(), Bias::Left, cx);
503 if let Some(cursor_item) = cursor.item() {
504 if cursor_item.key() == item.key() {
505 replaced = Some(cursor_item.clone());
506 cursor.next(cx);
507 }
508 }
509 new_tree.push(item, cx);
510 new_tree.push_tree(cursor.suffix(cx), cx);
511 new_tree
512 };
513 replaced
514 }
515
516 pub fn remove(&mut self, key: &T::Key, cx: &<T::Summary as Summary>::Context) -> Option<T> {
517 let mut removed = None;
518 *self = {
519 let mut cursor = self.cursor::<T::Key>();
520 let mut new_tree = cursor.slice(key, Bias::Left, cx);
521 if let Some(item) = cursor.item() {
522 if item.key() == *key {
523 removed = Some(item.clone());
524 cursor.next(cx);
525 }
526 }
527 new_tree.push_tree(cursor.suffix(cx), cx);
528 new_tree
529 };
530 removed
531 }
532
533 pub fn edit(
534 &mut self,
535 mut edits: Vec<Edit<T>>,
536 cx: &<T::Summary as Summary>::Context,
537 ) -> Vec<T> {
538 if edits.is_empty() {
539 return Vec::new();
540 }
541
542 let mut removed = Vec::new();
543 edits.sort_unstable_by_key(|item| item.key());
544
545 *self = {
546 let mut cursor = self.cursor::<T::Key>();
547 let mut new_tree = SumTree::new();
548 let mut buffered_items = Vec::new();
549
550 cursor.seek(&T::Key::default(), Bias::Left, cx);
551 for edit in edits {
552 let new_key = edit.key();
553 let mut old_item = cursor.item();
554
555 if old_item
556 .as_ref()
557 .map_or(false, |old_item| old_item.key() < new_key)
558 {
559 new_tree.extend(buffered_items.drain(..), cx);
560 let slice = cursor.slice(&new_key, Bias::Left, cx);
561 new_tree.push_tree(slice, cx);
562 old_item = cursor.item();
563 }
564
565 if let Some(old_item) = old_item {
566 if old_item.key() == new_key {
567 removed.push(old_item.clone());
568 cursor.next(cx);
569 }
570 }
571
572 match edit {
573 Edit::Insert(item) => {
574 buffered_items.push(item);
575 }
576 Edit::Remove(_) => {}
577 }
578 }
579
580 new_tree.extend(buffered_items, cx);
581 new_tree.push_tree(cursor.suffix(cx), cx);
582 new_tree
583 };
584
585 removed
586 }
587
588 pub fn get(&self, key: &T::Key, cx: &<T::Summary as Summary>::Context) -> Option<&T> {
589 let mut cursor = self.cursor::<T::Key>();
590 if cursor.seek(key, Bias::Left, cx) {
591 cursor.item()
592 } else {
593 None
594 }
595 }
596}
597
598impl<T: Item> Default for SumTree<T> {
599 fn default() -> Self {
600 Self::new()
601 }
602}
603
604#[derive(Clone, Debug)]
605pub enum Node<T: Item> {
606 Internal {
607 height: u8,
608 summary: T::Summary,
609 child_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
610 child_trees: ArrayVec<SumTree<T>, { 2 * TREE_BASE }>,
611 },
612 Leaf {
613 summary: T::Summary,
614 items: ArrayVec<T, { 2 * TREE_BASE }>,
615 item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
616 },
617}
618
619impl<T: Item> Node<T> {
620 fn is_leaf(&self) -> bool {
621 matches!(self, Node::Leaf { .. })
622 }
623
624 fn height(&self) -> u8 {
625 match self {
626 Node::Internal { height, .. } => *height,
627 Node::Leaf { .. } => 0,
628 }
629 }
630
631 fn summary(&self) -> &T::Summary {
632 match self {
633 Node::Internal { summary, .. } => summary,
634 Node::Leaf { summary, .. } => summary,
635 }
636 }
637
638 fn child_summaries(&self) -> &[T::Summary] {
639 match self {
640 Node::Internal {
641 child_summaries, ..
642 } => child_summaries.as_slice(),
643 Node::Leaf { item_summaries, .. } => item_summaries.as_slice(),
644 }
645 }
646
647 fn child_trees(&self) -> &ArrayVec<SumTree<T>, { 2 * TREE_BASE }> {
648 match self {
649 Node::Internal { child_trees, .. } => child_trees,
650 Node::Leaf { .. } => panic!("Leaf nodes have no child trees"),
651 }
652 }
653
654 fn items(&self) -> &ArrayVec<T, { 2 * TREE_BASE }> {
655 match self {
656 Node::Leaf { items, .. } => items,
657 Node::Internal { .. } => panic!("Internal nodes have no items"),
658 }
659 }
660
661 fn is_underflowing(&self) -> bool {
662 match self {
663 Node::Internal { child_trees, .. } => child_trees.len() < TREE_BASE,
664 Node::Leaf { items, .. } => items.len() < TREE_BASE,
665 }
666 }
667}
668
669#[derive(Debug)]
670pub enum Edit<T: KeyedItem> {
671 Insert(T),
672 Remove(T::Key),
673}
674
675impl<T: KeyedItem> Edit<T> {
676 fn key(&self) -> T::Key {
677 match self {
678 Edit::Insert(item) => item.key(),
679 Edit::Remove(key) => key.clone(),
680 }
681 }
682}
683
684fn sum<'a, T, I>(iter: I, cx: &T::Context) -> T
685where
686 T: 'a + Summary,
687 I: Iterator<Item = &'a T>,
688{
689 let mut sum = T::default();
690 for value in iter {
691 sum.add_summary(value, cx);
692 }
693 sum
694}
695
696#[cfg(test)]
697mod tests {
698 use super::*;
699 use rand::{distributions, prelude::*};
700 use std::cmp;
701
702 #[ctor::ctor]
703 fn init_logger() {
704 if std::env::var("RUST_LOG").is_ok() {
705 env_logger::init();
706 }
707 }
708
709 #[test]
710 fn test_extend_and_push_tree() {
711 let mut tree1 = SumTree::new();
712 tree1.extend(0..20, &());
713
714 let mut tree2 = SumTree::new();
715 tree2.extend(50..100, &());
716
717 tree1.push_tree(tree2, &());
718 assert_eq!(
719 tree1.items(&()),
720 (0..20).chain(50..100).collect::<Vec<u8>>()
721 );
722 }
723
724 #[test]
725 fn test_random() {
726 let mut starting_seed = 0;
727 if let Ok(value) = std::env::var("SEED") {
728 starting_seed = value.parse().expect("invalid SEED variable");
729 }
730 let mut num_iterations = 100;
731 if let Ok(value) = std::env::var("ITERATIONS") {
732 num_iterations = value.parse().expect("invalid ITERATIONS variable");
733 }
734 let num_operations = std::env::var("OPERATIONS")
735 .map_or(5, |o| o.parse().expect("invalid OPERATIONS variable"));
736
737 for seed in starting_seed..(starting_seed + num_iterations) {
738 eprintln!("seed = {}", seed);
739 let mut rng = StdRng::seed_from_u64(seed);
740
741 let rng = &mut rng;
742 let mut tree = SumTree::<u8>::new();
743 let count = rng.gen_range(0..10);
744 tree.extend(rng.sample_iter(distributions::Standard).take(count), &());
745
746 for _ in 0..num_operations {
747 let splice_end = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
748 let splice_start = rng.gen_range(0..splice_end + 1);
749 let count = rng.gen_range(0..3);
750 let tree_end = tree.extent::<Count>(&());
751 let new_items = rng
752 .sample_iter(distributions::Standard)
753 .take(count)
754 .collect::<Vec<u8>>();
755
756 let mut reference_items = tree.items(&());
757 reference_items.splice(splice_start..splice_end, new_items.clone());
758
759 tree = {
760 let mut cursor = tree.cursor::<Count>();
761 let mut new_tree = cursor.slice(&Count(splice_start), Bias::Right, &());
762 new_tree.extend(new_items, &());
763 cursor.seek(&Count(splice_end), Bias::Right, &());
764 new_tree.push_tree(cursor.slice(&tree_end, Bias::Right, &()), &());
765 new_tree
766 };
767
768 assert_eq!(tree.items(&()), reference_items);
769 assert_eq!(
770 tree.iter().collect::<Vec<_>>(),
771 tree.cursor::<()>().collect::<Vec<_>>()
772 );
773
774 log::info!("tree items: {:?}", tree.items(&()));
775
776 let mut filter_cursor = tree.filter::<_, Count>(|summary| summary.contains_even);
777 let expected_filtered_items = tree
778 .items(&())
779 .into_iter()
780 .enumerate()
781 .filter(|(_, item)| (item & 1) == 0)
782 .collect::<Vec<_>>();
783
784 let mut item_ix = if rng.gen() {
785 filter_cursor.next(&());
786 0
787 } else {
788 filter_cursor.prev(&());
789 expected_filtered_items.len().saturating_sub(1)
790 };
791 while item_ix < expected_filtered_items.len() {
792 log::info!("filter_cursor, item_ix: {}", item_ix);
793 let actual_item = filter_cursor.item().unwrap();
794 let (reference_index, reference_item) = expected_filtered_items[item_ix];
795 assert_eq!(actual_item, &reference_item);
796 assert_eq!(filter_cursor.start().0, reference_index);
797 log::info!("next");
798 filter_cursor.next(&());
799 item_ix += 1;
800
801 while item_ix > 0 && rng.gen_bool(0.2) {
802 log::info!("prev");
803 filter_cursor.prev(&());
804 item_ix -= 1;
805
806 if item_ix == 0 && rng.gen_bool(0.2) {
807 filter_cursor.prev(&());
808 assert_eq!(filter_cursor.item(), None);
809 assert_eq!(filter_cursor.start().0, 0);
810 filter_cursor.next(&());
811 }
812 }
813 }
814 assert_eq!(filter_cursor.item(), None);
815
816 let mut pos = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
817 let mut before_start = false;
818 let mut cursor = tree.cursor::<Count>();
819 cursor.seek(&Count(pos), Bias::Right, &());
820
821 for i in 0..10 {
822 assert_eq!(cursor.start().0, pos);
823
824 if pos > 0 {
825 assert_eq!(cursor.prev_item().unwrap(), &reference_items[pos - 1]);
826 } else {
827 assert_eq!(cursor.prev_item(), None);
828 }
829
830 if pos < reference_items.len() && !before_start {
831 assert_eq!(cursor.item().unwrap(), &reference_items[pos]);
832 } else {
833 assert_eq!(cursor.item(), None);
834 }
835
836 if i < 5 {
837 cursor.next(&());
838 if pos < reference_items.len() {
839 pos += 1;
840 before_start = false;
841 }
842 } else {
843 cursor.prev(&());
844 if pos == 0 {
845 before_start = true;
846 }
847 pos = pos.saturating_sub(1);
848 }
849 }
850 }
851
852 for _ in 0..10 {
853 let end = rng.gen_range(0..tree.extent::<Count>(&()).0 + 1);
854 let start = rng.gen_range(0..end + 1);
855 let start_bias = if rng.gen() { Bias::Left } else { Bias::Right };
856 let end_bias = if rng.gen() { Bias::Left } else { Bias::Right };
857
858 let mut cursor = tree.cursor::<Count>();
859 cursor.seek(&Count(start), start_bias, &());
860 let slice = cursor.slice(&Count(end), end_bias, &());
861
862 cursor.seek(&Count(start), start_bias, &());
863 let summary = cursor.summary::<_, Sum>(&Count(end), end_bias, &());
864
865 assert_eq!(summary.0, slice.summary().sum);
866 }
867 }
868 }
869
870 #[test]
871 fn test_cursor() {
872 // Empty tree
873 let tree = SumTree::<u8>::new();
874 let mut cursor = tree.cursor::<IntegersSummary>();
875 assert_eq!(
876 cursor.slice(&Count(0), Bias::Right, &()).items(&()),
877 Vec::<u8>::new()
878 );
879 assert_eq!(cursor.item(), None);
880 assert_eq!(cursor.prev_item(), None);
881 assert_eq!(cursor.start().sum, 0);
882 cursor.prev(&());
883 assert_eq!(cursor.item(), None);
884 assert_eq!(cursor.prev_item(), None);
885 assert_eq!(cursor.start().sum, 0);
886 cursor.next(&());
887 assert_eq!(cursor.item(), None);
888 assert_eq!(cursor.prev_item(), None);
889 assert_eq!(cursor.start().sum, 0);
890
891 // Single-element tree
892 let mut tree = SumTree::<u8>::new();
893 tree.extend(vec![1], &());
894 let mut cursor = tree.cursor::<IntegersSummary>();
895 assert_eq!(
896 cursor.slice(&Count(0), Bias::Right, &()).items(&()),
897 Vec::<u8>::new()
898 );
899 assert_eq!(cursor.item(), Some(&1));
900 assert_eq!(cursor.prev_item(), None);
901 assert_eq!(cursor.start().sum, 0);
902
903 cursor.next(&());
904 assert_eq!(cursor.item(), None);
905 assert_eq!(cursor.prev_item(), Some(&1));
906 assert_eq!(cursor.start().sum, 1);
907
908 cursor.prev(&());
909 assert_eq!(cursor.item(), Some(&1));
910 assert_eq!(cursor.prev_item(), None);
911 assert_eq!(cursor.start().sum, 0);
912
913 let mut cursor = tree.cursor::<IntegersSummary>();
914 assert_eq!(cursor.slice(&Count(1), Bias::Right, &()).items(&()), [1]);
915 assert_eq!(cursor.item(), None);
916 assert_eq!(cursor.prev_item(), Some(&1));
917 assert_eq!(cursor.start().sum, 1);
918
919 cursor.seek(&Count(0), Bias::Right, &());
920 assert_eq!(
921 cursor
922 .slice(&tree.extent::<Count>(&()), Bias::Right, &())
923 .items(&()),
924 [1]
925 );
926 assert_eq!(cursor.item(), None);
927 assert_eq!(cursor.prev_item(), Some(&1));
928 assert_eq!(cursor.start().sum, 1);
929
930 // Multiple-element tree
931 let mut tree = SumTree::new();
932 tree.extend(vec![1, 2, 3, 4, 5, 6], &());
933 let mut cursor = tree.cursor::<IntegersSummary>();
934
935 assert_eq!(cursor.slice(&Count(2), Bias::Right, &()).items(&()), [1, 2]);
936 assert_eq!(cursor.item(), Some(&3));
937 assert_eq!(cursor.prev_item(), Some(&2));
938 assert_eq!(cursor.start().sum, 3);
939
940 cursor.next(&());
941 assert_eq!(cursor.item(), Some(&4));
942 assert_eq!(cursor.prev_item(), Some(&3));
943 assert_eq!(cursor.start().sum, 6);
944
945 cursor.next(&());
946 assert_eq!(cursor.item(), Some(&5));
947 assert_eq!(cursor.prev_item(), Some(&4));
948 assert_eq!(cursor.start().sum, 10);
949
950 cursor.next(&());
951 assert_eq!(cursor.item(), Some(&6));
952 assert_eq!(cursor.prev_item(), Some(&5));
953 assert_eq!(cursor.start().sum, 15);
954
955 cursor.next(&());
956 cursor.next(&());
957 assert_eq!(cursor.item(), None);
958 assert_eq!(cursor.prev_item(), Some(&6));
959 assert_eq!(cursor.start().sum, 21);
960
961 cursor.prev(&());
962 assert_eq!(cursor.item(), Some(&6));
963 assert_eq!(cursor.prev_item(), Some(&5));
964 assert_eq!(cursor.start().sum, 15);
965
966 cursor.prev(&());
967 assert_eq!(cursor.item(), Some(&5));
968 assert_eq!(cursor.prev_item(), Some(&4));
969 assert_eq!(cursor.start().sum, 10);
970
971 cursor.prev(&());
972 assert_eq!(cursor.item(), Some(&4));
973 assert_eq!(cursor.prev_item(), Some(&3));
974 assert_eq!(cursor.start().sum, 6);
975
976 cursor.prev(&());
977 assert_eq!(cursor.item(), Some(&3));
978 assert_eq!(cursor.prev_item(), Some(&2));
979 assert_eq!(cursor.start().sum, 3);
980
981 cursor.prev(&());
982 assert_eq!(cursor.item(), Some(&2));
983 assert_eq!(cursor.prev_item(), Some(&1));
984 assert_eq!(cursor.start().sum, 1);
985
986 cursor.prev(&());
987 assert_eq!(cursor.item(), Some(&1));
988 assert_eq!(cursor.prev_item(), None);
989 assert_eq!(cursor.start().sum, 0);
990
991 cursor.prev(&());
992 assert_eq!(cursor.item(), None);
993 assert_eq!(cursor.prev_item(), None);
994 assert_eq!(cursor.start().sum, 0);
995
996 cursor.next(&());
997 assert_eq!(cursor.item(), Some(&1));
998 assert_eq!(cursor.prev_item(), None);
999 assert_eq!(cursor.start().sum, 0);
1000
1001 let mut cursor = tree.cursor::<IntegersSummary>();
1002 assert_eq!(
1003 cursor
1004 .slice(&tree.extent::<Count>(&()), Bias::Right, &())
1005 .items(&()),
1006 tree.items(&())
1007 );
1008 assert_eq!(cursor.item(), None);
1009 assert_eq!(cursor.prev_item(), Some(&6));
1010 assert_eq!(cursor.start().sum, 21);
1011
1012 cursor.seek(&Count(3), Bias::Right, &());
1013 assert_eq!(
1014 cursor
1015 .slice(&tree.extent::<Count>(&()), Bias::Right, &())
1016 .items(&()),
1017 [4, 5, 6]
1018 );
1019 assert_eq!(cursor.item(), None);
1020 assert_eq!(cursor.prev_item(), Some(&6));
1021 assert_eq!(cursor.start().sum, 21);
1022
1023 // Seeking can bias left or right
1024 cursor.seek(&Count(1), Bias::Left, &());
1025 assert_eq!(cursor.item(), Some(&1));
1026 cursor.seek(&Count(1), Bias::Right, &());
1027 assert_eq!(cursor.item(), Some(&2));
1028
1029 // Slicing without resetting starts from where the cursor is parked at.
1030 cursor.seek(&Count(1), Bias::Right, &());
1031 assert_eq!(
1032 cursor.slice(&Count(3), Bias::Right, &()).items(&()),
1033 vec![2, 3]
1034 );
1035 assert_eq!(
1036 cursor.slice(&Count(6), Bias::Left, &()).items(&()),
1037 vec![4, 5]
1038 );
1039 assert_eq!(
1040 cursor.slice(&Count(6), Bias::Right, &()).items(&()),
1041 vec![6]
1042 );
1043 }
1044
1045 #[test]
1046 fn test_edit() {
1047 let mut tree = SumTree::<u8>::new();
1048
1049 let removed = tree.edit(vec![Edit::Insert(1), Edit::Insert(2), Edit::Insert(0)], &());
1050 assert_eq!(tree.items(&()), vec![0, 1, 2]);
1051 assert_eq!(removed, Vec::<u8>::new());
1052 assert_eq!(tree.get(&0, &()), Some(&0));
1053 assert_eq!(tree.get(&1, &()), Some(&1));
1054 assert_eq!(tree.get(&2, &()), Some(&2));
1055 assert_eq!(tree.get(&4, &()), None);
1056
1057 let removed = tree.edit(vec![Edit::Insert(2), Edit::Insert(4), Edit::Remove(0)], &());
1058 assert_eq!(tree.items(&()), vec![1, 2, 4]);
1059 assert_eq!(removed, vec![0, 2]);
1060 assert_eq!(tree.get(&0, &()), None);
1061 assert_eq!(tree.get(&1, &()), Some(&1));
1062 assert_eq!(tree.get(&2, &()), Some(&2));
1063 assert_eq!(tree.get(&4, &()), Some(&4));
1064 }
1065
1066 #[derive(Clone, Default, Debug)]
1067 pub struct IntegersSummary {
1068 count: usize,
1069 sum: usize,
1070 contains_even: bool,
1071 max: u8,
1072 }
1073
1074 #[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
1075 struct Count(usize);
1076
1077 #[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
1078 struct Sum(usize);
1079
1080 impl Item for u8 {
1081 type Summary = IntegersSummary;
1082
1083 fn summary(&self) -> Self::Summary {
1084 IntegersSummary {
1085 count: 1,
1086 sum: *self as usize,
1087 contains_even: (*self & 1) == 0,
1088 max: *self,
1089 }
1090 }
1091 }
1092
1093 impl KeyedItem for u8 {
1094 type Key = u8;
1095
1096 fn key(&self) -> Self::Key {
1097 *self
1098 }
1099 }
1100
1101 impl Summary for IntegersSummary {
1102 type Context = ();
1103
1104 fn add_summary(&mut self, other: &Self, _: &()) {
1105 self.count += other.count;
1106 self.sum += other.sum;
1107 self.contains_even |= other.contains_even;
1108 self.max = cmp::max(self.max, other.max);
1109 }
1110 }
1111
1112 impl<'a> Dimension<'a, IntegersSummary> for u8 {
1113 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1114 *self = summary.max;
1115 }
1116 }
1117
1118 impl<'a> Dimension<'a, IntegersSummary> for Count {
1119 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1120 self.0 += summary.count;
1121 }
1122 }
1123
1124 impl<'a> SeekTarget<'a, IntegersSummary, IntegersSummary> for Count {
1125 fn cmp(&self, cursor_location: &IntegersSummary, _: &()) -> Ordering {
1126 self.0.cmp(&cursor_location.count)
1127 }
1128 }
1129
1130 impl<'a> Dimension<'a, IntegersSummary> for Sum {
1131 fn add_summary(&mut self, summary: &IntegersSummary, _: &()) {
1132 self.0 += summary.sum;
1133 }
1134 }
1135}