@@ -1,1125 +0,0 @@
1−use crate::{
2− cached_set::{CacheId, CachedSet},
3− change_list::ChangeListBuilder,
4− events::EventsRegistry,
5− node::{Attribute, ElementNode, Listener, Node, NodeKind, TextNode},
6−};
7−use fxhash::{FxHashMap, FxHashSet};
8−use std::cmp::Ordering;
9−use std::u32;
10−use wasm_bindgen::UnwrapThrowExt;
11−
12−// Diff the `old` node with the `new` node. Emits instructions to modify a
13−// physical DOM node that reflects `old` into something that reflects `new`.
14−//
15−// Upon entry to this function, the physical DOM node must be on the top of the
16−// change list stack:
17−//
18−// [... node]
19−//
20−// The change list stack is in the same state when this function exits.
21−pub(crate) fn diff(
22− cached_set: &CachedSet,
23− change_list: &mut ChangeListBuilder,
24− registry: &mut EventsRegistry,
25− old: &Node,
26− new: &Node,
27− cached_roots: &mut FxHashSet<CacheId>,
28−) {
29− match (&new.kind, &old.kind) {
30− (
31− &NodeKind::Text(TextNode { text: new_text }),
32− &NodeKind::Text(TextNode { text: old_text }),
33− ) => {
34− if new_text != old_text {
35− change_list.commit_traversal();
36− change_list.set_text(new_text);
37− }
38− }
39−
40− (&NodeKind::Text(_), &NodeKind::Element(_)) => {
41− change_list.commit_traversal();
42− create(cached_set, change_list, registry, new, cached_roots);
43− registry.remove_subtree(&old);
44− change_list.replace_with();
45− }
46−
47− (&NodeKind::Element(_), &NodeKind::Text(_)) => {
48− change_list.commit_traversal();
49− create(cached_set, change_list, registry, new, cached_roots);
50− // Note: text nodes cannot have event listeners, so we don't need to
51− // remove the old node's listeners from our registry her.
52− change_list.replace_with();
53− }
54−
55− (
56− &NodeKind::Element(ElementNode {
57− key: _,
58− tag_name: new_tag_name,
59− listeners: new_listeners,
60− attributes: new_attributes,
61− children: new_children,
62− namespace: new_namespace,
63− }),
64− &NodeKind::Element(ElementNode {
65− key: _,
66− tag_name: old_tag_name,
67− listeners: old_listeners,
68− attributes: old_attributes,
69− children: old_children,
70− namespace: old_namespace,
71− }),
72− ) => {
73− if new_tag_name != old_tag_name || new_namespace != old_namespace {
74− change_list.commit_traversal();
75− create(cached_set, change_list, registry, new, cached_roots);
76− registry.remove_subtree(&old);
77− change_list.replace_with();
78− return;
79− }
80− diff_listeners(change_list, registry, old_listeners, new_listeners);
81− diff_attributes(change_list, old_attributes, new_attributes, new_namespace.is_some());
82− diff_children(
83− cached_set,
84− change_list,
85− registry,
86− old_children,
87− new_children,
88− cached_roots,
89− );
90− }
91−
92− // Both the new and old nodes are cached.
93− (&NodeKind::Cached(ref new), &NodeKind::Cached(ref old)) => {
94− cached_roots.insert(new.id);
95−
96− if new.id == old.id {
97− // This is the same cached node, so nothing has changed!
98− return;
99− }
100−
101− let (new, new_template) = cached_set.get(new.id);
102− let (old, old_template) = cached_set.get(old.id);
103− if new_template == old_template {
104− // If they are both using the same template, then just diff the
105− // subtrees.
106− diff(cached_set, change_list, registry, old, new, cached_roots);
107− } else {
108− // Otherwise, they are probably different enough that
109− // re-constructing the subtree from scratch should be faster.
110− // This doubly holds true if we have a new template.
111− change_list.commit_traversal();
112− create_and_replace(
113− cached_set,
114− change_list,
115− registry,
116− new_template,
117− old,
118− new,
119− cached_roots,
120− );
121− }
122− }
123−
124− // New cached node when the old node was not cached. In this scenario,
125− // we assume that they are pretty different, and it isn't worth diffing
126− // the subtrees, so we just create the new cached node afresh.
127− (&NodeKind::Cached(ref c), _) => {
128− change_list.commit_traversal();
129− cached_roots.insert(c.id);
130− let (new, new_template) = cached_set.get(c.id);
131− create_and_replace(
132− cached_set,
133− change_list,
134− registry,
135− new_template,
136− old,
137− new,
138− cached_roots,
139− );
140− }
141−
142− // Old cached node and new non-cached node. Again, assume that they are
143− // probably pretty different and create the new non-cached node afresh.
144− (_, &NodeKind::Cached(_)) => {
145− change_list.commit_traversal();
146− create(cached_set, change_list, registry, new, cached_roots);
147− registry.remove_subtree(&old);
148− change_list.replace_with();
149− }
150− }
151−}
152−
153−// Diff event listeners between `old` and `new`.
154−//
155−// The listeners' node must be on top of the change list stack:
156−//
157−// [... node]
158−//
159−// The change list stack is left unchanged.
160−fn diff_listeners(
161− change_list: &mut ChangeListBuilder,
162− registry: &mut EventsRegistry,
163− old: &[Listener],
164− new: &[Listener],
165−) {
166− if !old.is_empty() || !new.is_empty() {
167− change_list.commit_traversal();
168− }
169−
170− 'outer1: for new_l in new {
171− unsafe {
172− // Safety relies on removing `new_l` from the registry manually at
173− // the end of its lifetime. This happens below in the `'outer2`
174− // loop, and elsewhere in diffing when removing old dom trees.
175− registry.add(new_l);
176− }
177−
178− for old_l in old {
179− if new_l.event == old_l.event {
180− change_list.update_event_listener(new_l);
181− continue 'outer1;
182− }
183− }
184−
185− change_list.new_event_listener(new_l);
186− }
187−
188− 'outer2: for old_l in old {
189− registry.remove(old_l);
190−
191− for new_l in new {
192− if new_l.event == old_l.event {
193− continue 'outer2;
194− }
195− }
196− change_list.remove_event_listener(old_l.event);
197− }
198−}
199−
200−// Diff a node's attributes.
201−//
202−// The attributes' node must be on top of the change list stack:
203−//
204−// [... node]
205−//
206−// The change list stack is left unchanged.
207−fn diff_attributes(change_list: &mut ChangeListBuilder, old: &[Attribute], new: &[Attribute], is_namespaced: bool) {
208− // Do O(n^2) passes to add/update and remove attributes, since
209− // there are almost always very few attributes.
210− 'outer: for new_attr in new {
211− if new_attr.is_volatile() {
212− change_list.commit_traversal();
213− change_list.set_attribute(new_attr.name, new_attr.value, is_namespaced);
214− } else {
215− for old_attr in old {
216− if old_attr.name == new_attr.name {
217− if old_attr.value != new_attr.value {
218− change_list.commit_traversal();
219− change_list.set_attribute(new_attr.name, new_attr.value, is_namespaced);
220− }
221− continue 'outer;
222− }
223− }
224−
225− change_list.commit_traversal();
226− change_list.set_attribute(new_attr.name, new_attr.value, is_namespaced);
227− }
228− }
229−
230− 'outer2: for old_attr in old {
231− for new_attr in new {
232− if old_attr.name == new_attr.name {
233− continue 'outer2;
234− }
235− }
236−
237− change_list.commit_traversal();
238− change_list.remove_attribute(old_attr.name);
239− }
240−}
241−
242−// Diff the given set of old and new children.
243−//
244−// The parent must be on top of the change list stack when this function is
245−// entered:
246−//
247−// [... parent]
248−//
249−// the change list stack is in the same state when this function returns.
250−fn diff_children(
251− cached_set: &CachedSet,
252− change_list: &mut ChangeListBuilder,
253− registry: &mut EventsRegistry,
254− old: &[Node],
255− new: &[Node],
256− cached_roots: &mut FxHashSet<CacheId>,
257−) {
258− if new.is_empty() {
259− if !old.is_empty() {
260− change_list.commit_traversal();
261− remove_all_children(change_list, registry, old);
262− }
263− return;
264− }
265−
266− if new.len() == 1 {
267− match (old.first(), &new[0]) {
268− (
269− Some(&Node {
270− kind: NodeKind::Text(TextNode { text: old_text }),
271− }),
272− &Node {
273− kind: NodeKind::Text(TextNode { text: new_text }),
274− },
275− ) if old_text == new_text => {
276− // Don't take this fast path...
277− }
278− (
279− _,
280− &Node {
281− kind: NodeKind::Text(TextNode { text }),
282− },
283− ) => {
284− change_list.commit_traversal();
285− change_list.set_text(text);
286− for o in old {
287− registry.remove_subtree(o);
288− }
289− return;
290− }
291− (_, _) => {}
292− }
293− }
294−
295− if old.is_empty() {
296− if !new.is_empty() {
297− change_list.commit_traversal();
298− create_and_append_children(cached_set, change_list, registry, new, cached_roots);
299− }
300− return;
301− }
302−
303− let new_is_keyed = new[0].key().is_some();
304− let old_is_keyed = old[0].key().is_some();
305−
306− debug_assert!(
307− new.iter().all(|n| n.key().is_some() == new_is_keyed),
308− "all siblings must be keyed or all siblings must be non-keyed"
309− );
310− debug_assert!(
311− old.iter().all(|o| o.key().is_some() == old_is_keyed),
312− "all siblings must be keyed or all siblings must be non-keyed"
313− );
314−
315− if new_is_keyed && old_is_keyed {
316− let t = change_list.next_temporary();
317− diff_keyed_children(cached_set, change_list, registry, old, new, cached_roots);
318− change_list.set_next_temporary(t);
319− } else {
320− diff_non_keyed_children(cached_set, change_list, registry, old, new, cached_roots);
321− }
322−}
323−
324−// Diffing "keyed" children.
325−//
326−// With keyed children, we care about whether we delete, move, or create nodes
327−// versus mutate existing nodes in place. Presumably there is some sort of CSS
328−// transition animation that makes the virtual DOM diffing algorithm
329−// observable. By specifying keys for nodes, we know which virtual DOM nodes
330−// must reuse (or not reuse) the same physical DOM nodes.
331−//
332−// This is loosely based on Inferno's keyed patching implementation. However, we
333−// have to modify the algorithm since we are compiling the diff down into change
334−// list instructions that will be executed later, rather than applying the
335−// changes to the DOM directly as we compare virtual DOMs.
336−//
337−// https://github.com/infernojs/inferno/blob/36fd96/packages/inferno/src/DOM/patching.ts#L530-L739
338−//
339−// When entering this function, the parent must be on top of the change list
340−// stack:
341−//
342−// [... parent]
343−//
344−// Upon exiting, the change list stack is in the same state.
345−fn diff_keyed_children(
346− cached_set: &CachedSet,
347− change_list: &mut ChangeListBuilder,
348− registry: &mut EventsRegistry,
349− old: &[Node],
350− new: &[Node],
351− cached_roots: &mut FxHashSet<CacheId>,
352−) {
353− if cfg!(debug_assertions) {
354− let mut keys = FxHashSet::default();
355− let mut assert_unique_keys = |children: &[Node]| {
356− keys.clear();
357− for child in children {
358− let key = child.key();
359− debug_assert!(
360− key.is_some(),
361− "if any sibling is keyed, all siblings must be keyed"
362− );
363− keys.insert(key);
364− }
365− debug_assert_eq!(
366− children.len(),
367− keys.len(),
368− "keyed siblings must each have a unique key"
369− );
370− };
371− assert_unique_keys(old);
372− assert_unique_keys(new);
373− }
374−
375− // First up, we diff all the nodes with the same key at the beginning of the
376− // children.
377− //
378− // `shared_prefix_count` is the count of how many nodes at the start of
379− // `new` and `old` share the same keys.
380− let shared_prefix_count =
381− match diff_keyed_prefix(cached_set, change_list, registry, old, new, cached_roots) {
382− KeyedPrefixResult::Finished => return,
383− KeyedPrefixResult::MoreWorkToDo(count) => count,
384− };
385−
386− // Next, we find out how many of the nodes at the end of the children have
387− // the same key. We do _not_ diff them yet, since we want to emit the change
388− // list instructions such that they can be applied in a single pass over the
389− // DOM. Instead, we just save this information for later.
390− //
391− // `shared_suffix_count` is the count of how many nodes at the end of `new`
392− // and `old` share the same keys.
393− let shared_suffix_count = old[shared_prefix_count..]
394− .iter()
395− .rev()
396− .zip(new[shared_prefix_count..].iter().rev())
397− .take_while(|&(old, new)| old.key() == new.key())
398− .count();
399−
400− let old_shared_suffix_start = old.len() - shared_suffix_count;
401− let new_shared_suffix_start = new.len() - shared_suffix_count;
402−
403− // Ok, we now hopefully have a smaller range of children in the middle
404− // within which to re-order nodes with the same keys, remove old nodes with
405− // now-unused keys, and create new nodes with fresh keys.
406− diff_keyed_middle(
407− cached_set,
408− change_list,
409− registry,
410− &old[shared_prefix_count..old_shared_suffix_start],
411− &new[shared_prefix_count..new_shared_suffix_start],
412− cached_roots,
413− shared_prefix_count,
414− shared_suffix_count,
415− old_shared_suffix_start,
416− );
417−
418− // Finally, diff the nodes at the end of `old` and `new` that share keys.
419− let old_suffix = &old[old_shared_suffix_start..];
420− let new_suffix = &new[new_shared_suffix_start..];
421− debug_assert_eq!(old_suffix.len(), new_suffix.len());
422− if !old_suffix.is_empty() {
423− diff_keyed_suffix(
424− cached_set,
425− change_list,
426− registry,
427− old_suffix,
428− new_suffix,
429− cached_roots,
430− new_shared_suffix_start,
431− );
432− }
433−}
434−
435−enum KeyedPrefixResult {
436− // Fast path: we finished diffing all the children just by looking at the
437− // prefix of shared keys!
438− Finished,
439− // There is more diffing work to do. Here is a count of how many children at
440− // the beginning of `new` and `old` we already processed.
441− MoreWorkToDo(usize),
442−}
443−
444−// Diff the prefix of children in `new` and `old` that share the same keys in
445−// the same order.
446−//
447−// Upon entry of this function, the change list stack must be:
448−//
449−// [... parent]
450−//
451−// Upon exit, the change list stack is the same.
452−fn diff_keyed_prefix(
453− cached_set: &CachedSet,
454− change_list: &mut ChangeListBuilder,
455− registry: &mut EventsRegistry,
456− old: &[Node],
457− new: &[Node],
458− cached_roots: &mut FxHashSet<CacheId>,
459−) -> KeyedPrefixResult {
460− change_list.go_down();
461− let mut shared_prefix_count = 0;
462−
463− for (i, (old, new)) in old.iter().zip(new.iter()).enumerate() {
464− if old.key() != new.key() {
465− break;
466− }
467−
468− change_list.go_to_sibling(i);
469− diff(cached_set, change_list, registry, old, new, cached_roots);
470− shared_prefix_count += 1;
471− }
472−
473− // If that was all of the old children, then create and append the remaining
474− // new children and we're finished.
475− if shared_prefix_count == old.len() {
476− change_list.go_up();
477− change_list.commit_traversal();
478− create_and_append_children(
479− cached_set,
480− change_list,
481− registry,
482− &new[shared_prefix_count..],
483− cached_roots,
484− );
485− return KeyedPrefixResult::Finished;
486− }
487−
488− // And if that was all of the new children, then remove all of the remaining
489− // old children and we're finished.
490− if shared_prefix_count == new.len() {
491− change_list.go_to_sibling(shared_prefix_count);
492− change_list.commit_traversal();
493− remove_self_and_next_siblings(change_list, registry, &old[shared_prefix_count..]);
494− return KeyedPrefixResult::Finished;
495− }
496−
497− change_list.go_up();
498− KeyedPrefixResult::MoreWorkToDo(shared_prefix_count)
499−}
500−
501−// The most-general, expensive code path for keyed children diffing.
502−//
503−// We find the longest subsequence within `old` of children that are relatively
504−// ordered the same way in `new` (via finding a longest-increasing-subsequence
505−// of the old child's index within `new`). The children that are elements of
506−// this subsequence will remain in place, minimizing the number of DOM moves we
507−// will have to do.
508−//
509−// Upon entry to this function, the change list stack must be:
510−//
511−// [... parent]
512−//
513−// Upon exit from this function, it will be restored to that same state.
514−fn diff_keyed_middle(
515− cached_set: &CachedSet,
516− change_list: &mut ChangeListBuilder,
517− registry: &mut EventsRegistry,
518− old: &[Node],
519− mut new: &[Node],
520− cached_roots: &mut FxHashSet<CacheId>,
521− shared_prefix_count: usize,
522− shared_suffix_count: usize,
523− old_shared_suffix_start: usize,
524−) {
525− // Should have already diffed the shared-key prefixes and suffixes.
526− debug_assert_ne!(new.first().map(|n| n.key()), old.first().map(|o| o.key()));
527− debug_assert_ne!(new.last().map(|n| n.key()), old.last().map(|o| o.key()));
528−
529− // The algorithm below relies upon using `u32::MAX` as a sentinel
530− // value, so if we have that many new nodes, it won't work. This
531− // check is a bit academic (hence only enabled in debug), since
532− // wasm32 doesn't have enough address space to hold that many nodes
533− // in memory.
534− debug_assert!(new.len() < u32::MAX as usize);
535−
536− // Map from each `old` node's key to its index within `old`.
537− let mut old_key_to_old_index = FxHashMap::default();
538− old_key_to_old_index.reserve(old.len());
539− old_key_to_old_index.extend(old.iter().enumerate().map(|(i, o)| (o.key(), i)));
540−
541− // The set of shared keys between `new` and `old`.
542− let mut shared_keys = FxHashSet::default();
543− // Map from each index in `new` to the index of the node in `old` that
544− // has the same key.
545− let mut new_index_to_old_index = Vec::with_capacity(new.len());
546− new_index_to_old_index.extend(new.iter().map(|n| {
547− let key = n.key();
548− if let Some(&i) = old_key_to_old_index.get(&key) {
549− shared_keys.insert(key);
550− i
551− } else {
552− u32::MAX as usize
553− }
554− }));
555−
556− // If none of the old keys are reused by the new children, then we
557− // remove all the remaining old children and create the new children
558− // afresh.
559− if shared_suffix_count == 0 && shared_keys.is_empty() {
560− if shared_prefix_count == 0 {
561− change_list.commit_traversal();
562− remove_all_children(change_list, registry, old);
563− } else {
564− change_list.go_down_to_child(shared_prefix_count);
565− change_list.commit_traversal();
566− remove_self_and_next_siblings(change_list, registry, &old[shared_prefix_count..]);
567− }
568− create_and_append_children(cached_set, change_list, registry, new, cached_roots);
569− return;
570− }
571−
572− // Save each of the old children whose keys are reused in the new
573− // children.
574− let mut old_index_to_temp = vec![u32::MAX; old.len()];
575− let mut start = 0;
576− loop {
577− let end = (start..old.len())
578− .find(|&i| {
579− let key = old[i].key();
580− !shared_keys.contains(&key)
581− })
582− .unwrap_or(old.len());
583−
584− if end - start > 0 {
585− change_list.commit_traversal();
586− let mut t = change_list.save_children_to_temporaries(
587− shared_prefix_count + start,
588− shared_prefix_count + end,
589− );
590− for i in start..end {
591− old_index_to_temp[i] = t;
592− t += 1;
593− }
594− }
595−
596− debug_assert!(end <= old.len());
597− if end == old.len() {
598− break;
599− } else {
600− start = end + 1;
601− }
602− }
603−
604− // Remove any old children whose keys were not reused in the new
605− // children. Remove from the end first so that we don't mess up indices.
606− let mut removed_count = 0;
607− for (i, old_child) in old.iter().enumerate().rev() {
608− if !shared_keys.contains(&old_child.key()) {
609− registry.remove_subtree(old_child);
610− change_list.commit_traversal();
611− change_list.remove_child(i + shared_prefix_count);
612− removed_count += 1;
613− }
614− }
615−
616− // If there aren't any more new children, then we are done!
617− if new.is_empty() {
618− return;
619− }
620−
621− // The longest increasing subsequence within `new_index_to_old_index`. This
622− // is the longest sequence on DOM nodes in `old` that are relatively ordered
623− // correctly within `new`. We will leave these nodes in place in the DOM,
624− // and only move nodes that are not part of the LIS. This results in the
625− // maximum number of DOM nodes left in place, AKA the minimum number of DOM
626− // nodes moved.
627− let mut new_index_is_in_lis = FxHashSet::default();
628− new_index_is_in_lis.reserve(new_index_to_old_index.len());
629− let mut predecessors = vec![0; new_index_to_old_index.len()];
630− let mut starts = vec![0; new_index_to_old_index.len()];
631− longest_increasing_subsequence::lis_with(
632− &new_index_to_old_index,
633− &mut new_index_is_in_lis,
634− |a, b| a < b,
635− &mut predecessors,
636− &mut starts,
637− );
638−
639− // Now we will iterate from the end of the new children back to the
640− // beginning, diffing old children we are reusing and if they aren't in the
641− // LIS moving them to their new destination, or creating new children. Note
642− // that iterating in reverse order lets us use `Node.prototype.insertBefore`
643− // to move/insert children.
644− //
645− // But first, we ensure that we have a child on the change list stack that
646− // we can `insertBefore`. We handle this once before looping over `new`
647− // children, so that we don't have to keep checking on every loop iteration.
648− if shared_suffix_count > 0 {
649− // There is a shared suffix after these middle children. We will be
650− // inserting before that shared suffix, so add the first child of that
651− // shared suffix to the change list stack.
652− //
653− // [... parent]
654− change_list.go_down_to_child(old_shared_suffix_start - removed_count);
655− // [... parent first_child_of_shared_suffix]
656− } else {
657− // There is no shared suffix coming after these middle children.
658− // Therefore we have to process the last child in `new` and move it to
659− // the end of the parent's children if it isn't already there.
660− let last_index = new.len() - 1;
661− let last = new.last().unwrap_throw();
662− new = &new[..new.len() - 1];
663− if shared_keys.contains(&last.key()) {
664− let old_index = new_index_to_old_index[last_index];
665− let temp = old_index_to_temp[old_index];
666− // [... parent]
667− change_list.go_down_to_temp_child(temp);
668− // [... parent last]
669− diff(
670− cached_set,
671− change_list,
672− registry,
673− &old[old_index],
674− last,
675− cached_roots,
676− );
677− if new_index_is_in_lis.contains(&last_index) {
678− // Don't move it, since it is already where it needs to be.
679− } else {
680− change_list.commit_traversal();
681− // [... parent last]
682− change_list.append_child();
683− // [... parent]
684− change_list.go_down_to_temp_child(temp);
685− // [... parent last]
686− }
687− } else {
688− change_list.commit_traversal();
689− // [... parent]
690− create(cached_set, change_list, registry, last, cached_roots);
691− // [... parent last]
692− change_list.append_child();
693− // [... parent]
694− change_list.go_down_to_reverse_child(0);
695− // [... parent last]
696− }
697− }
698−
699− for (new_index, new_child) in new.iter().enumerate().rev() {
700− let old_index = new_index_to_old_index[new_index];
701− if old_index == u32::MAX as usize {
702− debug_assert!(!shared_keys.contains(&new_child.key()));
703− change_list.commit_traversal();
704− // [... parent successor]
705− create(cached_set, change_list, registry, new_child, cached_roots);
706− // [... parent successor new_child]
707− change_list.insert_before();
708− // [... parent new_child]
709− } else {
710− debug_assert!(shared_keys.contains(&new_child.key()));
711− let temp = old_index_to_temp[old_index];
712− debug_assert_ne!(temp, u32::MAX);
713−
714− if new_index_is_in_lis.contains(&new_index) {
715− // [... parent successor]
716− change_list.go_to_temp_sibling(temp);
717− // [... parent new_child]
718− } else {
719− change_list.commit_traversal();
720− // [... parent successor]
721− change_list.push_temporary(temp);
722− // [... parent successor new_child]
723− change_list.insert_before();
724− // [... parent new_child]
725− }
726−
727− diff(
728− cached_set,
729− change_list,
730− registry,
731− &old[old_index],
732− new_child,
733− cached_roots,
734− );
735− }
736− }
737−
738− // [... parent child]
739− change_list.go_up();
740− // [... parent]
741−}
742−
743−// Diff the suffix of keyed children that share the same keys in the same order.
744−//
745−// The parent must be on the change list stack when we enter this function:
746−//
747−// [... parent]
748−//
749−// When this function exits, the change list stack remains the same.
750−fn diff_keyed_suffix(
751− cached_set: &CachedSet,
752− change_list: &mut ChangeListBuilder,
753− registry: &mut EventsRegistry,
754− old: &[Node],
755− new: &[Node],
756− cached_roots: &mut FxHashSet<CacheId>,
757− new_shared_suffix_start: usize,
758−) {
759− debug_assert_eq!(old.len(), new.len());
760− debug_assert!(!old.is_empty());
761−
762− // [... parent]
763− change_list.go_down();
764− // [... parent new_child]
765−
766− for (i, (old_child, new_child)) in old.iter().zip(new.iter()).enumerate() {
767− change_list.go_to_sibling(new_shared_suffix_start + i);
768− diff(
769− cached_set,
770− change_list,
771− registry,
772− old_child,
773− new_child,
774− cached_roots,
775− );
776− }
777−
778− // [... parent]
779− change_list.go_up();
780−}
781−
782−// Diff children that are not keyed.
783−//
784−// The parent must be on the top of the change list stack when entering this
785−// function:
786−//
787−// [... parent]
788−//
789−// the change list stack is in the same state when this function returns.
790−fn diff_non_keyed_children(
791− cached_set: &CachedSet,
792− change_list: &mut ChangeListBuilder,
793− registry: &mut EventsRegistry,
794− old: &[Node],
795− new: &[Node],
796− cached_roots: &mut FxHashSet<CacheId>,
797−) {
798− // Handled these cases in `diff_children` before calling this function.
799− debug_assert!(!new.is_empty());
800− debug_assert!(!old.is_empty());
801−
802− // [... parent]
803− change_list.go_down();
804− // [... parent child]
805−
806− for (i, (new_child, old_child)) in new.iter().zip(old.iter()).enumerate() {
807− // [... parent prev_child]
808− change_list.go_to_sibling(i);
809− // [... parent this_child]
810− diff(
811− cached_set,
812− change_list,
813− registry,
814− old_child,
815− new_child,
816− cached_roots,
817− );
818− }
819−
820− match old.len().cmp(&new.len()) {
821− Ordering::Greater => {
822− // [... parent prev_child]
823− change_list.go_to_sibling(new.len());
824− // [... parent first_child_to_remove]
825− change_list.commit_traversal();
826− remove_self_and_next_siblings(change_list, registry, &old[new.len()..]);
827− // [... parent]
828− }
829− Ordering::Less => {
830− // [... parent last_child]
831− change_list.go_up();
832− // [... parent]
833− change_list.commit_traversal();
834− create_and_append_children(
835− cached_set,
836− change_list,
837− registry,
838− &new[old.len()..],
839− cached_roots,
840− );
841− }
842− Ordering::Equal => {
843− // [... parent child]
844− change_list.go_up();
845− // [... parent]
846− }
847− }
848−}
849−
850−// Create the given children and append them to the parent node.
851−//
852−// The parent node must currently be on top of the change list stack:
853−//
854−// [... parent]
855−//
856−// When this function returns, the change list stack is in the same state.
857−fn create_and_append_children(
858− cached_set: &CachedSet,
859− change_list: &mut ChangeListBuilder,
860− registry: &mut EventsRegistry,
861− new: &[Node],
862− cached_roots: &mut FxHashSet<CacheId>,
863−) {
864− debug_assert!(change_list.traversal_is_committed());
865− for child in new {
866− create(cached_set, change_list, registry, child, cached_roots);
867− change_list.append_child();
868− }
869−}
870−
871−// Remove all of a node's children.
872−//
873−// The change list stack must have this shape upon entry to this function:
874−//
875−// [... parent]
876−//
877−// When this function returns, the change list stack is in the same state.
878−fn remove_all_children(
879− change_list: &mut ChangeListBuilder,
880− registry: &mut EventsRegistry,
881− old: &[Node],
882−) {
883− debug_assert!(change_list.traversal_is_committed());
884− for child in old {
885− registry.remove_subtree(child);
886− }
887− // Fast way to remove all children: set the node's textContent to an empty
888− // string.
889− change_list.set_text("");
890−}
891−
892−// Remove the current child and all of its following siblings.
893−//
894−// The change list stack must have this shape upon entry to this function:
895−//
896−// [... parent child]
897−//
898−// After the function returns, the child is no longer on the change list stack:
899−//
900−// [... parent]
901−fn remove_self_and_next_siblings(
902− change_list: &mut ChangeListBuilder,
903− registry: &mut EventsRegistry,
904− old: &[Node],
905−) {
906− debug_assert!(change_list.traversal_is_committed());
907− for child in old {
908− registry.remove_subtree(child);
909− }
910− change_list.remove_self_and_next_siblings();
911−}
912−
913−// Emit instructions to create the given virtual node.
914−//
915−// The change list stack may have any shape upon entering this function:
916−//
917−// [...]
918−//
919−// When this function returns, the new node is on top of the change list stack:
920−//
921−// [... node]
922−fn create(
923− cached_set: &CachedSet,
924− change_list: &mut ChangeListBuilder,
925− registry: &mut EventsRegistry,
926− node: &Node,
927− cached_roots: &mut FxHashSet<CacheId>,
928−) {
929− debug_assert!(change_list.traversal_is_committed());
930− match node.kind {
931− NodeKind::Text(TextNode { text }) => {
932− change_list.create_text_node(text);
933− }
934− NodeKind::Element(&ElementNode {
935− key: _,
936− tag_name,
937− listeners,
938− attributes,
939− children,
940− namespace,
941− }) => {
942− if let Some(namespace) = namespace {
943− change_list.create_element_ns(tag_name, namespace);
944− } else {
945− change_list.create_element(tag_name);
946− }
947−
948− for l in listeners {
949− unsafe {
950− registry.add(l);
951− }
952− change_list.new_event_listener(l);
953− }
954−
955− for attr in attributes {
956− change_list.set_attribute(&attr.name, &attr.value, namespace.is_some());
957− }
958−
959− // Fast path: if there is a single text child, it is faster to
960− // create-and-append the text node all at once via setting the
961− // parent's `textContent` in a single change list instruction than
962− // to emit three instructions to (1) create a text node, (2) set its
963− // text content, and finally (3) append the text node to this
964− // parent.
965− if children.len() == 1 {
966− if let Node {
967− kind: NodeKind::Text(TextNode { text }),
968− } = children[0]
969− {
970− change_list.set_text(text);
971− return;
972− }
973− }
974−
975− for child in children {
976− create(cached_set, change_list, registry, child, cached_roots);
977− change_list.append_child();
978− }
979− }
980− NodeKind::Cached(ref c) => {
981− cached_roots.insert(c.id);
982− let (node, template) = cached_set.get(c.id);
983− if let Some(template) = template {
984− create_with_template(
985− cached_set,
986− change_list,
987− registry,
988− template,
989− node,
990− cached_roots,
991− );
992− } else {
993− create(cached_set, change_list, registry, node, cached_roots);
994− }
995− }
996− }
997−}
998−
999−// Get or create the template.
1000−//
1001−// Upon entering this function the change list stack may be in any shape:
1002−//
1003−// [...]
1004−//
1005−// When this function returns, it leaves a freshly cloned copy of the template
1006−// on the top of the change list stack:
1007−//
1008−// [... template]
1009−#[inline]
1010−fn get_or_create_template<'a>(
1011− cached_set: &'a CachedSet,
1012− change_list: &mut ChangeListBuilder,
1013− registry: &mut EventsRegistry,
1014− cached_roots: &mut FxHashSet<CacheId>,
1015− template_id: CacheId,
1016−) -> (&'a Node<'a>, bool) {
1017− let (template, template_template) = cached_set.get(template_id);
1018− debug_assert!(
1019− template_template.is_none(),
1020− "templates should not be templated themselves"
1021− );
1022−
1023− // If we haven't already created and saved the physical DOM subtree for this
1024− // template, do that now.
1025− if change_list.has_template(template_id) {
1026− // Clone the template and push it onto the stack.
1027− //
1028− // [...]
1029− change_list.push_template(template_id);
1030− // [... template]
1031−
1032− (template, true)
1033− } else {
1034− // [...]
1035− create(cached_set, change_list, registry, template, cached_roots);
1036− // [... template]
1037− change_list.save_template(template_id);
1038− // [... template]
1039−
1040− (template, false)
1041− }
1042−}
1043−
1044−fn create_and_replace(
1045− cached_set: &CachedSet,
1046− change_list: &mut ChangeListBuilder,
1047− registry: &mut EventsRegistry,
1048− new_template: Option<CacheId>,
1049− old: &Node,
1050− new: &Node,
1051− cached_roots: &mut FxHashSet<CacheId>,
1052−) {
1053− debug_assert!(change_list.traversal_is_committed());
1054−
1055− if let Some(template_id) = new_template {
1056− let (template, needs_listeners) =
1057− get_or_create_template(cached_set, change_list, registry, cached_roots, template_id);
1058− change_list.replace_with();
1059−
1060− let mut old_forcing = None;
1061− if needs_listeners {
1062− old_forcing = Some(change_list.push_force_new_listeners());
1063− }
1064−
1065− diff(
1066− cached_set,
1067− change_list,
1068− registry,
1069− template,
1070− new,
1071− cached_roots,
1072− );
1073−
1074− if let Some(old) = old_forcing {
1075− change_list.pop_force_new_listeners(old);
1076− }
1077−
1078− change_list.commit_traversal();
1079− } else {
1080− create(cached_set, change_list, registry, new, cached_roots);
1081− change_list.replace_with();
1082− }
1083− registry.remove_subtree(old);
1084−}
1085−
1086−fn create_with_template(
1087− cached_set: &CachedSet,
1088− change_list: &mut ChangeListBuilder,
1089− registry: &mut EventsRegistry,
1090− template_id: CacheId,
1091− node: &Node,
1092− cached_roots: &mut FxHashSet<CacheId>,
1093−) {
1094− debug_assert!(change_list.traversal_is_committed());
1095−
1096− // [...]
1097− let (template, needs_listeners) =
1098− get_or_create_template(cached_set, change_list, registry, cached_roots, template_id);
1099− // [... template]
1100−
1101− // Now diff the node with its template.
1102− //
1103− // We must force adding new listeners instead of updating existing ones,
1104− // since listeners don't get cloned in `cloneNode`.
1105− let mut old_forcing = None;
1106− if needs_listeners {
1107− old_forcing = Some(change_list.push_force_new_listeners());
1108− }
1109−
1110− diff(
1111− cached_set,
1112− change_list,
1113− registry,
1114− template,
1115− node,
1116− cached_roots,
1117− );
1118−
1119− if let Some(old) = old_forcing {
1120− change_list.pop_force_new_listeners(old);
1121− }
1122−
1123− // Make sure that we come back up to the level we were at originally.
1124− change_list.commit_traversal();
1125−}