1use super::*;
2use arrayvec::ArrayVec;
3use std::{cmp::Ordering, mem, sync::Arc};
4
5#[derive(Clone)]
6struct StackEntry<'a, T: Item, D> {
7 tree: &'a SumTree<T>,
8 index: u32,
9 position: D,
10}
11
12impl<'a, T: Item, D> StackEntry<'a, T, D> {
13 #[inline]
14 fn index(&self) -> usize {
15 self.index as usize
16 }
17}
18
19impl<T: Item + fmt::Debug, D: fmt::Debug> fmt::Debug for StackEntry<'_, T, D> {
20 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
21 f.debug_struct("StackEntry")
22 .field("index", &self.index)
23 .field("position", &self.position)
24 .finish()
25 }
26}
27
28#[derive(Clone)]
29pub struct Cursor<'a, 'b, T: Item, D> {
30 tree: &'a SumTree<T>,
31 stack: ArrayVec<StackEntry<'a, T, D>, 16>,
32 position: D,
33 did_seek: bool,
34 at_end: bool,
35 cx: <T::Summary as Summary>::Context<'b>,
36}
37
38impl<T: Item + fmt::Debug, D: fmt::Debug> fmt::Debug for Cursor<'_, '_, T, D>
39where
40 T::Summary: fmt::Debug,
41{
42 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
43 f.debug_struct("Cursor")
44 .field("tree", &self.tree)
45 .field("stack", &self.stack)
46 .field("position", &self.position)
47 .field("did_seek", &self.did_seek)
48 .field("at_end", &self.at_end)
49 .finish()
50 }
51}
52
53pub struct Iter<'a, T: Item> {
54 tree: &'a SumTree<T>,
55 stack: ArrayVec<StackEntry<'a, T, ()>, 16>,
56}
57
58impl<'a, 'b, T, D> Cursor<'a, 'b, T, D>
59where
60 T: Item,
61 D: Dimension<'a, T::Summary>,
62{
63 pub fn new(tree: &'a SumTree<T>, cx: <T::Summary as Summary>::Context<'b>) -> Self {
64 Self {
65 tree,
66 stack: ArrayVec::new(),
67 position: D::zero(cx),
68 did_seek: false,
69 at_end: tree.is_empty(),
70 cx,
71 }
72 }
73
74 fn reset(&mut self) {
75 self.did_seek = false;
76 self.at_end = self.tree.is_empty();
77 self.stack.truncate(0);
78 self.position = D::zero(self.cx);
79 }
80
81 pub fn start(&self) -> &D {
82 &self.position
83 }
84
85 #[track_caller]
86 pub fn end(&self) -> D {
87 if let Some(item_summary) = self.item_summary() {
88 let mut end = self.start().clone();
89 end.add_summary(item_summary, self.cx);
90 end
91 } else {
92 self.start().clone()
93 }
94 }
95
96 /// Item is None, when the list is empty, or this cursor is at the end of the list.
97 #[track_caller]
98 pub fn item(&self) -> Option<&'a T> {
99 self.assert_did_seek();
100 if let Some(entry) = self.stack.last() {
101 match *entry.tree.0 {
102 Node::Leaf { ref items, .. } => {
103 if entry.index() == items.len() {
104 None
105 } else {
106 Some(&items[entry.index()])
107 }
108 }
109 _ => unreachable!(),
110 }
111 } else {
112 None
113 }
114 }
115
116 #[track_caller]
117 pub fn item_summary(&self) -> Option<&'a T::Summary> {
118 self.assert_did_seek();
119 if let Some(entry) = self.stack.last() {
120 match *entry.tree.0 {
121 Node::Leaf {
122 ref item_summaries, ..
123 } => {
124 if entry.index() == item_summaries.len() {
125 None
126 } else {
127 Some(&item_summaries[entry.index()])
128 }
129 }
130 _ => unreachable!(),
131 }
132 } else {
133 None
134 }
135 }
136
137 #[track_caller]
138 pub fn next_item(&self) -> Option<&'a T> {
139 self.assert_did_seek();
140 if let Some(entry) = self.stack.last() {
141 if entry.index() == entry.tree.0.items().len() - 1 {
142 if let Some(next_leaf) = self.next_leaf() {
143 Some(next_leaf.0.items().first().unwrap())
144 } else {
145 None
146 }
147 } else {
148 match *entry.tree.0 {
149 Node::Leaf { ref items, .. } => Some(&items[entry.index() + 1]),
150 _ => unreachable!(),
151 }
152 }
153 } else if self.at_end {
154 None
155 } else {
156 self.tree.first()
157 }
158 }
159
160 #[track_caller]
161 fn next_leaf(&self) -> Option<&'a SumTree<T>> {
162 for entry in self.stack.iter().rev().skip(1) {
163 if entry.index() < entry.tree.0.child_trees().len() - 1 {
164 match *entry.tree.0 {
165 Node::Internal {
166 ref child_trees, ..
167 } => return Some(child_trees[entry.index() + 1].leftmost_leaf()),
168 Node::Leaf { .. } => unreachable!(),
169 };
170 }
171 }
172 None
173 }
174
175 #[track_caller]
176 pub fn prev_item(&self) -> Option<&'a T> {
177 self.assert_did_seek();
178 if let Some(entry) = self.stack.last() {
179 if entry.index() == 0 {
180 if let Some(prev_leaf) = self.prev_leaf() {
181 Some(prev_leaf.0.items().last().unwrap())
182 } else {
183 None
184 }
185 } else {
186 match *entry.tree.0 {
187 Node::Leaf { ref items, .. } => Some(&items[entry.index() - 1]),
188 _ => unreachable!(),
189 }
190 }
191 } else if self.at_end {
192 self.tree.last()
193 } else {
194 None
195 }
196 }
197
198 #[track_caller]
199 fn prev_leaf(&self) -> Option<&'a SumTree<T>> {
200 for entry in self.stack.iter().rev().skip(1) {
201 if entry.index() != 0 {
202 match *entry.tree.0 {
203 Node::Internal {
204 ref child_trees, ..
205 } => return Some(child_trees[entry.index() - 1].rightmost_leaf()),
206 Node::Leaf { .. } => unreachable!(),
207 };
208 }
209 }
210 None
211 }
212
213 #[track_caller]
214 pub fn prev(&mut self) {
215 self.search_backward(|_| true)
216 }
217
218 #[track_caller]
219 pub fn search_backward<F>(&mut self, mut filter_node: F)
220 where
221 F: FnMut(&T::Summary) -> bool,
222 {
223 if !self.did_seek {
224 self.did_seek = true;
225 self.at_end = true;
226 }
227
228 if self.at_end {
229 self.position = D::zero(self.cx);
230 self.at_end = self.tree.is_empty();
231 if !self.tree.is_empty() {
232 self.stack.push(StackEntry {
233 tree: self.tree,
234 index: self.tree.0.child_summaries().len() as u32,
235 position: D::from_summary(self.tree.summary(), self.cx),
236 });
237 }
238 }
239
240 let mut descending = false;
241 while !self.stack.is_empty() {
242 if let Some(StackEntry { position, .. }) = self.stack.iter().rev().nth(1) {
243 self.position = position.clone();
244 } else {
245 self.position = D::zero(self.cx);
246 }
247
248 let entry = self.stack.last_mut().unwrap();
249 if !descending {
250 if entry.index() == 0 {
251 self.stack.pop();
252 continue;
253 } else {
254 entry.index -= 1;
255 }
256 }
257
258 for summary in &entry.tree.0.child_summaries()[..entry.index()] {
259 self.position.add_summary(summary, self.cx);
260 }
261 entry.position = self.position.clone();
262
263 descending = filter_node(&entry.tree.0.child_summaries()[entry.index()]);
264 match entry.tree.0.as_ref() {
265 Node::Internal { child_trees, .. } => {
266 if descending {
267 let tree = &child_trees[entry.index()];
268 self.stack.push(StackEntry {
269 position: D::zero(self.cx),
270 tree,
271 index: tree.0.child_summaries().len() as u32 - 1,
272 })
273 }
274 }
275 Node::Leaf { .. } => {
276 if descending {
277 break;
278 }
279 }
280 }
281 }
282 }
283
284 #[track_caller]
285 pub fn next(&mut self) {
286 self.search_forward(|_| true)
287 }
288
289 #[track_caller]
290 pub fn search_forward<F>(&mut self, mut filter_node: F)
291 where
292 F: FnMut(&T::Summary) -> bool,
293 {
294 let mut descend = false;
295
296 if self.stack.is_empty() {
297 if !self.at_end {
298 self.stack.push(StackEntry {
299 tree: self.tree,
300 index: 0,
301 position: D::zero(self.cx),
302 });
303 descend = true;
304 }
305 self.did_seek = true;
306 }
307
308 while !self.stack.is_empty() {
309 let new_subtree = {
310 let entry = self.stack.last_mut().unwrap();
311 match entry.tree.0.as_ref() {
312 Node::Internal {
313 child_trees,
314 child_summaries,
315 ..
316 } => {
317 if !descend {
318 entry.index += 1;
319 entry.position = self.position.clone();
320 }
321
322 while entry.index() < child_summaries.len() {
323 let next_summary = &child_summaries[entry.index()];
324 if filter_node(next_summary) {
325 break;
326 } else {
327 entry.index += 1;
328 entry.position.add_summary(next_summary, self.cx);
329 self.position.add_summary(next_summary, self.cx);
330 }
331 }
332
333 child_trees.get(entry.index())
334 }
335 Node::Leaf { item_summaries, .. } => {
336 if !descend {
337 let item_summary = &item_summaries[entry.index()];
338 entry.index += 1;
339 entry.position.add_summary(item_summary, self.cx);
340 self.position.add_summary(item_summary, self.cx);
341 }
342
343 loop {
344 if let Some(next_item_summary) = item_summaries.get(entry.index()) {
345 if filter_node(next_item_summary) {
346 return;
347 } else {
348 entry.index += 1;
349 entry.position.add_summary(next_item_summary, self.cx);
350 self.position.add_summary(next_item_summary, self.cx);
351 }
352 } else {
353 break None;
354 }
355 }
356 }
357 }
358 };
359
360 if let Some(subtree) = new_subtree {
361 descend = true;
362 self.stack.push(StackEntry {
363 tree: subtree,
364 index: 0,
365 position: self.position.clone(),
366 });
367 } else {
368 descend = false;
369 self.stack.pop();
370 }
371 }
372
373 self.at_end = self.stack.is_empty();
374 debug_assert!(self.stack.is_empty() || self.stack.last().unwrap().tree.0.is_leaf());
375 }
376
377 #[track_caller]
378 fn assert_did_seek(&self) {
379 assert!(
380 self.did_seek,
381 "Must call `seek`, `next` or `prev` before calling this method"
382 );
383 }
384}
385
386impl<'a, 'b, T, D> Cursor<'a, 'b, T, D>
387where
388 T: Item,
389 D: Dimension<'a, T::Summary>,
390{
391 /// Returns whether we found the item you were seeking for.
392 #[track_caller]
393 pub fn seek<Target>(&mut self, pos: &Target, bias: Bias) -> bool
394 where
395 Target: SeekTarget<'a, T::Summary, D>,
396 {
397 self.reset();
398 self.seek_internal(pos, bias, &mut ())
399 }
400
401 /// Returns whether we found the item you were seeking for.
402 #[track_caller]
403 pub fn seek_forward<Target>(&mut self, pos: &Target, bias: Bias) -> bool
404 where
405 Target: SeekTarget<'a, T::Summary, D>,
406 {
407 self.seek_internal(pos, bias, &mut ())
408 }
409
410 /// Advances the cursor and returns traversed items as a tree.
411 #[track_caller]
412 pub fn slice<Target>(&mut self, end: &Target, bias: Bias) -> SumTree<T>
413 where
414 Target: SeekTarget<'a, T::Summary, D>,
415 {
416 let mut slice = SliceSeekAggregate {
417 tree: SumTree::new(self.cx),
418 leaf_items: ArrayVec::new(),
419 leaf_item_summaries: ArrayVec::new(),
420 leaf_summary: <T::Summary as Summary>::zero(self.cx),
421 };
422 self.seek_internal(end, bias, &mut slice);
423 slice.tree
424 }
425
426 #[track_caller]
427 pub fn suffix(&mut self) -> SumTree<T> {
428 self.slice(&End::new(), Bias::Right)
429 }
430
431 #[track_caller]
432 pub fn summary<Target, Output>(&mut self, end: &Target, bias: Bias) -> Output
433 where
434 Target: SeekTarget<'a, T::Summary, D>,
435 Output: Dimension<'a, T::Summary>,
436 {
437 let mut summary = SummarySeekAggregate(Output::zero(self.cx));
438 self.seek_internal(end, bias, &mut summary);
439 summary.0
440 }
441
442 /// Returns whether we found the item you were seeking for.
443 #[track_caller]
444 fn seek_internal(
445 &mut self,
446 target: &dyn SeekTarget<'a, T::Summary, D>,
447 bias: Bias,
448 aggregate: &mut dyn SeekAggregate<'a, T>,
449 ) -> bool {
450 assert!(
451 target.cmp(&self.position, self.cx) >= Ordering::Equal,
452 "cannot seek backward",
453 );
454
455 if !self.did_seek {
456 self.did_seek = true;
457 self.stack.push(StackEntry {
458 tree: self.tree,
459 index: 0,
460 position: D::zero(self.cx),
461 });
462 }
463
464 let mut ascending = false;
465 'outer: while let Some(entry) = self.stack.last_mut() {
466 match *entry.tree.0 {
467 Node::Internal {
468 ref child_summaries,
469 ref child_trees,
470 ..
471 } => {
472 if ascending {
473 entry.index += 1;
474 entry.position = self.position.clone();
475 }
476
477 for (child_tree, child_summary) in child_trees[entry.index()..]
478 .iter()
479 .zip(&child_summaries[entry.index()..])
480 {
481 let mut child_end = self.position.clone();
482 child_end.add_summary(child_summary, self.cx);
483
484 let comparison = target.cmp(&child_end, self.cx);
485 if comparison == Ordering::Greater
486 || (comparison == Ordering::Equal && bias == Bias::Right)
487 {
488 self.position = child_end;
489 aggregate.push_tree(child_tree, child_summary, self.cx);
490 entry.index += 1;
491 entry.position = self.position.clone();
492 } else {
493 self.stack.push(StackEntry {
494 tree: child_tree,
495 index: 0,
496 position: self.position.clone(),
497 });
498 ascending = false;
499 continue 'outer;
500 }
501 }
502 }
503 Node::Leaf {
504 ref items,
505 ref item_summaries,
506 ..
507 } => {
508 aggregate.begin_leaf();
509
510 for (item, item_summary) in items[entry.index()..]
511 .iter()
512 .zip(&item_summaries[entry.index()..])
513 {
514 let mut child_end = self.position.clone();
515 child_end.add_summary(item_summary, self.cx);
516
517 let comparison = target.cmp(&child_end, self.cx);
518 if comparison == Ordering::Greater
519 || (comparison == Ordering::Equal && bias == Bias::Right)
520 {
521 self.position = child_end;
522 aggregate.push_item(item, item_summary, self.cx);
523 entry.index += 1;
524 } else {
525 aggregate.end_leaf(self.cx);
526 break 'outer;
527 }
528 }
529
530 aggregate.end_leaf(self.cx);
531 }
532 }
533
534 self.stack.pop();
535 ascending = true;
536 }
537
538 self.at_end = self.stack.is_empty();
539 debug_assert!(self.stack.is_empty() || self.stack.last().unwrap().tree.0.is_leaf());
540
541 let mut end = self.position.clone();
542 if bias == Bias::Left
543 && let Some(summary) = self.item_summary()
544 {
545 end.add_summary(summary, self.cx);
546 }
547
548 target.cmp(&end, self.cx) == Ordering::Equal
549 }
550}
551
552impl<'a, T: Item> Iter<'a, T> {
553 pub(crate) fn new(tree: &'a SumTree<T>) -> Self {
554 Self {
555 tree,
556 stack: Default::default(),
557 }
558 }
559}
560
561impl<'a, T: Item> Iterator for Iter<'a, T> {
562 type Item = &'a T;
563
564 fn next(&mut self) -> Option<Self::Item> {
565 let mut descend = false;
566
567 if self.stack.is_empty() {
568 self.stack.push(StackEntry {
569 tree: self.tree,
570 index: 0,
571 position: (),
572 });
573 descend = true;
574 }
575
576 while !self.stack.is_empty() {
577 let new_subtree = {
578 let entry = self.stack.last_mut().unwrap();
579 match entry.tree.0.as_ref() {
580 Node::Internal { child_trees, .. } => {
581 if !descend {
582 entry.index += 1;
583 }
584 child_trees.get(entry.index())
585 }
586 Node::Leaf { items, .. } => {
587 if !descend {
588 entry.index += 1;
589 }
590
591 if let Some(next_item) = items.get(entry.index()) {
592 return Some(next_item);
593 } else {
594 None
595 }
596 }
597 }
598 };
599
600 if let Some(subtree) = new_subtree {
601 descend = true;
602 self.stack.push(StackEntry {
603 tree: subtree,
604 index: 0,
605 position: (),
606 });
607 } else {
608 descend = false;
609 self.stack.pop();
610 }
611 }
612
613 None
614 }
615}
616
617impl<'a, 'b, T: Item, D> Iterator for Cursor<'a, 'b, T, D>
618where
619 D: Dimension<'a, T::Summary>,
620{
621 type Item = &'a T;
622
623 fn next(&mut self) -> Option<Self::Item> {
624 if !self.did_seek {
625 self.next();
626 }
627
628 if let Some(item) = self.item() {
629 self.next();
630 Some(item)
631 } else {
632 None
633 }
634 }
635}
636
637pub struct FilterCursor<'a, 'b, F, T: Item, D> {
638 cursor: Cursor<'a, 'b, T, D>,
639 filter_node: F,
640}
641
642impl<'a, 'b, F, T: Item, D> FilterCursor<'a, 'b, F, T, D>
643where
644 F: FnMut(&T::Summary) -> bool,
645 T: Item,
646 D: Dimension<'a, T::Summary>,
647{
648 pub fn new(
649 tree: &'a SumTree<T>,
650 cx: <T::Summary as Summary>::Context<'b>,
651 filter_node: F,
652 ) -> Self {
653 let cursor = tree.cursor::<D>(cx);
654 Self {
655 cursor,
656 filter_node,
657 }
658 }
659
660 pub fn start(&self) -> &D {
661 self.cursor.start()
662 }
663
664 pub fn end(&self) -> D {
665 self.cursor.end()
666 }
667
668 pub fn item(&self) -> Option<&'a T> {
669 self.cursor.item()
670 }
671
672 pub fn item_summary(&self) -> Option<&'a T::Summary> {
673 self.cursor.item_summary()
674 }
675
676 pub fn next(&mut self) {
677 self.cursor.search_forward(&mut self.filter_node);
678 }
679
680 pub fn prev(&mut self) {
681 self.cursor.search_backward(&mut self.filter_node);
682 }
683}
684
685impl<'a, 'b, F, T: Item, U> Iterator for FilterCursor<'a, 'b, F, T, U>
686where
687 F: FnMut(&T::Summary) -> bool,
688 U: Dimension<'a, T::Summary>,
689{
690 type Item = &'a T;
691
692 fn next(&mut self) -> Option<Self::Item> {
693 if !self.cursor.did_seek {
694 self.next();
695 }
696
697 if let Some(item) = self.item() {
698 self.cursor.search_forward(&mut self.filter_node);
699 Some(item)
700 } else {
701 None
702 }
703 }
704}
705
706trait SeekAggregate<'a, T: Item> {
707 fn begin_leaf(&mut self);
708 fn end_leaf(&mut self, cx: <T::Summary as Summary>::Context<'_>);
709 fn push_item(
710 &mut self,
711 item: &'a T,
712 summary: &'a T::Summary,
713 cx: <T::Summary as Summary>::Context<'_>,
714 );
715 fn push_tree(
716 &mut self,
717 tree: &'a SumTree<T>,
718 summary: &'a T::Summary,
719 cx: <T::Summary as Summary>::Context<'_>,
720 );
721}
722
723struct SliceSeekAggregate<T: Item> {
724 tree: SumTree<T>,
725 leaf_items: ArrayVec<T, { 2 * TREE_BASE }>,
726 leaf_item_summaries: ArrayVec<T::Summary, { 2 * TREE_BASE }>,
727 leaf_summary: T::Summary,
728}
729
730struct SummarySeekAggregate<D>(D);
731
732impl<T: Item> SeekAggregate<'_, T> for () {
733 fn begin_leaf(&mut self) {}
734 fn end_leaf(&mut self, _: <T::Summary as Summary>::Context<'_>) {}
735 fn push_item(&mut self, _: &T, _: &T::Summary, _: <T::Summary as Summary>::Context<'_>) {}
736 fn push_tree(
737 &mut self,
738 _: &SumTree<T>,
739 _: &T::Summary,
740 _: <T::Summary as Summary>::Context<'_>,
741 ) {
742 }
743}
744
745impl<T: Item> SeekAggregate<'_, T> for SliceSeekAggregate<T> {
746 fn begin_leaf(&mut self) {}
747 fn end_leaf(&mut self, cx: <T::Summary as Summary>::Context<'_>) {
748 self.tree.append(
749 SumTree(Arc::new(Node::Leaf {
750 summary: mem::replace(&mut self.leaf_summary, <T::Summary as Summary>::zero(cx)),
751 items: mem::take(&mut self.leaf_items),
752 item_summaries: mem::take(&mut self.leaf_item_summaries),
753 })),
754 cx,
755 );
756 }
757 fn push_item(
758 &mut self,
759 item: &T,
760 summary: &T::Summary,
761 cx: <T::Summary as Summary>::Context<'_>,
762 ) {
763 self.leaf_items.push(item.clone());
764 self.leaf_item_summaries.push(summary.clone());
765 Summary::add_summary(&mut self.leaf_summary, summary, cx);
766 }
767 fn push_tree(
768 &mut self,
769 tree: &SumTree<T>,
770 _: &T::Summary,
771 cx: <T::Summary as Summary>::Context<'_>,
772 ) {
773 self.tree.append(tree.clone(), cx);
774 }
775}
776
777impl<'a, T: Item, D> SeekAggregate<'a, T> for SummarySeekAggregate<D>
778where
779 D: Dimension<'a, T::Summary>,
780{
781 fn begin_leaf(&mut self) {}
782 fn end_leaf(&mut self, _: <T::Summary as Summary>::Context<'_>) {}
783 fn push_item(
784 &mut self,
785 _: &T,
786 summary: &'a T::Summary,
787 cx: <T::Summary as Summary>::Context<'_>,
788 ) {
789 self.0.add_summary(summary, cx);
790 }
791 fn push_tree(
792 &mut self,
793 _: &SumTree<T>,
794 summary: &'a T::Summary,
795 cx: <T::Summary as Summary>::Context<'_>,
796 ) {
797 self.0.add_summary(summary, cx);
798 }
799}
800
801struct End<D>(PhantomData<D>);
802
803impl<D> End<D> {
804 fn new() -> Self {
805 Self(PhantomData)
806 }
807}
808
809impl<'a, S: Summary, D: Dimension<'a, S>> SeekTarget<'a, S, D> for End<D> {
810 fn cmp(&self, _: &D, _: S::Context<'_>) -> Ordering {
811 Ordering::Greater
812 }
813}
814
815impl<D> fmt::Debug for End<D> {
816 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
817 f.debug_tuple("End").finish()
818 }
819}