1/// KeyDispatch is where GPUI deals with binding actions to key events.
2///
3/// The key pieces to making a key binding work are to define an action,
4/// implement a method that takes that action as a type parameter,
5/// and then to register the action during render on a focused node
6/// with a keymap context:
7///
8/// ```rust
9/// actions!(editor,[Undo, Redo]);;
10///
11/// impl Editor {
12/// fn undo(&mut self, _: &Undo, _cx: &mut ViewContext<Self>) { ... }
13/// fn redo(&mut self, _: &Redo, _cx: &mut ViewContext<Self>) { ... }
14/// }
15///
16/// impl Render for Editor {
17/// fn render(&mut self, cx: &mut ViewContext<Self>) -> impl IntoElement {
18/// div()
19/// .track_focus(&self.focus_handle)
20/// .keymap_context("Editor")
21/// .on_action(cx.listener(Editor::undo))
22/// .on_action(cx.listener(Editor::redo))
23/// ...
24/// }
25/// }
26///```
27///
28/// The keybindings themselves are managed independently by calling cx.bind_keys().
29/// (Though mostly when developing Zed itself, you just need to add a new line to
30/// assets/keymaps/default.json).
31///
32/// ```rust
33/// cx.bind_keys([
34/// KeyBinding::new("cmd-z", Editor::undo, Some("Editor")),
35/// KeyBinding::new("cmd-shift-z", Editor::redo, Some("Editor")),
36/// ])
37/// ```
38///
39/// With all of this in place, GPUI will ensure that if you have an Editor that contains
40/// the focus, hitting cmd-z will Undo.
41///
42/// In real apps, it is a little more complicated than this, because typically you have
43/// several nested views that each register keyboard handlers. In this case action matching
44/// bubbles up from the bottom. For example in Zed, the Workspace is the top-level view, which contains Pane's, which contain Editors. If there are conflicting keybindings defined
45/// then the Editor's bindings take precedence over the Pane's bindings, which take precedence over the Workspace.
46///
47/// In GPUI, keybindings are not limited to just single keystrokes, you can define
48/// sequences by separating the keys with a space:
49///
50/// KeyBinding::new("cmd-k left", pane::SplitLeft, Some("Pane"))
51///
52use crate::{
53 Action, ActionRegistry, DispatchPhase, ElementContext, EntityId, FocusId, KeyBinding,
54 KeyContext, Keymap, KeymatchResult, Keystroke, KeystrokeMatcher, ModifiersChangedEvent,
55 WindowContext,
56};
57use collections::FxHashMap;
58use smallvec::SmallVec;
59use std::{
60 any::{Any, TypeId},
61 cell::RefCell,
62 mem,
63 ops::Range,
64 rc::Rc,
65};
66
67#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
68pub(crate) struct DispatchNodeId(usize);
69
70pub(crate) struct DispatchTree {
71 node_stack: Vec<DispatchNodeId>,
72 pub(crate) context_stack: Vec<KeyContext>,
73 view_stack: Vec<EntityId>,
74 nodes: Vec<DispatchNode>,
75 focusable_node_ids: FxHashMap<FocusId, DispatchNodeId>,
76 view_node_ids: FxHashMap<EntityId, DispatchNodeId>,
77 keystroke_matchers: FxHashMap<SmallVec<[KeyContext; 4]>, KeystrokeMatcher>,
78 keymap: Rc<RefCell<Keymap>>,
79 action_registry: Rc<ActionRegistry>,
80}
81
82#[derive(Default)]
83pub(crate) struct DispatchNode {
84 pub key_listeners: Vec<KeyListener>,
85 pub action_listeners: Vec<DispatchActionListener>,
86 pub modifiers_changed_listeners: Vec<ModifiersChangedListener>,
87 pub context: Option<KeyContext>,
88 pub focus_id: Option<FocusId>,
89 view_id: Option<EntityId>,
90 parent: Option<DispatchNodeId>,
91}
92
93pub(crate) struct ReusedSubtree {
94 old_range: Range<usize>,
95 new_range: Range<usize>,
96}
97
98impl ReusedSubtree {
99 pub fn refresh_node_id(&self, node_id: DispatchNodeId) -> DispatchNodeId {
100 debug_assert!(
101 self.old_range.contains(&node_id.0),
102 "node {} was not part of the reused subtree {:?}",
103 node_id.0,
104 self.old_range
105 );
106 DispatchNodeId((node_id.0 - self.old_range.start) + self.new_range.start)
107 }
108}
109
110type KeyListener = Rc<dyn Fn(&dyn Any, DispatchPhase, &mut ElementContext)>;
111type ModifiersChangedListener = Rc<dyn Fn(&ModifiersChangedEvent, &mut ElementContext)>;
112
113#[derive(Clone)]
114pub(crate) struct DispatchActionListener {
115 pub(crate) action_type: TypeId,
116 pub(crate) listener: Rc<dyn Fn(&dyn Any, DispatchPhase, &mut WindowContext)>,
117}
118
119impl DispatchTree {
120 pub fn new(keymap: Rc<RefCell<Keymap>>, action_registry: Rc<ActionRegistry>) -> Self {
121 Self {
122 node_stack: Vec::new(),
123 context_stack: Vec::new(),
124 view_stack: Vec::new(),
125 nodes: Vec::new(),
126 focusable_node_ids: FxHashMap::default(),
127 view_node_ids: FxHashMap::default(),
128 keystroke_matchers: FxHashMap::default(),
129 keymap,
130 action_registry,
131 }
132 }
133
134 pub fn clear(&mut self) {
135 self.node_stack.clear();
136 self.context_stack.clear();
137 self.view_stack.clear();
138 self.nodes.clear();
139 self.focusable_node_ids.clear();
140 self.view_node_ids.clear();
141 self.keystroke_matchers.clear();
142 }
143
144 pub fn len(&self) -> usize {
145 self.nodes.len()
146 }
147
148 pub fn push_node(&mut self) -> DispatchNodeId {
149 let parent = self.node_stack.last().copied();
150 let node_id = DispatchNodeId(self.nodes.len());
151
152 self.nodes.push(DispatchNode {
153 parent,
154 ..Default::default()
155 });
156 self.node_stack.push(node_id);
157 node_id
158 }
159
160 pub fn set_active_node(&mut self, node_id: DispatchNodeId) {
161 let next_node_parent = self.nodes[node_id.0].parent;
162 while self.node_stack.last().copied() != next_node_parent && !self.node_stack.is_empty() {
163 self.pop_node();
164 }
165
166 if self.node_stack.last().copied() == next_node_parent {
167 self.node_stack.push(node_id);
168 let active_node = &self.nodes[node_id.0];
169 if let Some(view_id) = active_node.view_id {
170 self.view_stack.push(view_id)
171 }
172 if let Some(context) = active_node.context.clone() {
173 self.context_stack.push(context);
174 }
175 } else {
176 debug_assert_eq!(self.node_stack.len(), 0);
177
178 let mut current_node_id = Some(node_id);
179 while let Some(node_id) = current_node_id {
180 let node = &self.nodes[node_id.0];
181 if let Some(context) = node.context.clone() {
182 self.context_stack.push(context);
183 }
184 if node.view_id.is_some() {
185 self.view_stack.push(node.view_id.unwrap());
186 }
187 self.node_stack.push(node_id);
188 current_node_id = node.parent;
189 }
190
191 self.context_stack.reverse();
192 self.view_stack.reverse();
193 self.node_stack.reverse();
194 }
195 }
196
197 pub fn set_key_context(&mut self, context: KeyContext) {
198 self.active_node().context = Some(context.clone());
199 self.context_stack.push(context);
200 }
201
202 pub fn set_focus_id(&mut self, focus_id: FocusId) {
203 let node_id = *self.node_stack.last().unwrap();
204 self.nodes[node_id.0].focus_id = Some(focus_id);
205 self.focusable_node_ids.insert(focus_id, node_id);
206 }
207
208 pub fn parent_view_id(&mut self) -> Option<EntityId> {
209 self.view_stack.last().copied()
210 }
211
212 pub fn set_view_id(&mut self, view_id: EntityId) {
213 if self.view_stack.last().copied() != Some(view_id) {
214 let node_id = *self.node_stack.last().unwrap();
215 self.nodes[node_id.0].view_id = Some(view_id);
216 self.view_node_ids.insert(view_id, node_id);
217 self.view_stack.push(view_id);
218 }
219 }
220
221 pub fn pop_node(&mut self) {
222 let node = &self.nodes[self.active_node_id().unwrap().0];
223 if node.context.is_some() {
224 self.context_stack.pop();
225 }
226 if node.view_id.is_some() {
227 self.view_stack.pop();
228 }
229 self.node_stack.pop();
230 }
231
232 fn move_node(&mut self, source: &mut DispatchNode) {
233 self.push_node();
234 if let Some(context) = source.context.clone() {
235 self.set_key_context(context);
236 }
237 if let Some(focus_id) = source.focus_id {
238 self.set_focus_id(focus_id);
239 }
240 if let Some(view_id) = source.view_id {
241 self.set_view_id(view_id);
242 }
243
244 let target = self.active_node();
245 target.key_listeners = mem::take(&mut source.key_listeners);
246 target.action_listeners = mem::take(&mut source.action_listeners);
247 target.modifiers_changed_listeners = mem::take(&mut source.modifiers_changed_listeners);
248 }
249
250 pub fn reuse_subtree(&mut self, old_range: Range<usize>, source: &mut Self) -> ReusedSubtree {
251 let new_range = self.nodes.len()..self.nodes.len() + old_range.len();
252
253 let mut source_stack = vec![];
254 for (source_node_id, source_node) in source
255 .nodes
256 .iter_mut()
257 .enumerate()
258 .skip(old_range.start)
259 .take(old_range.len())
260 {
261 let source_node_id = DispatchNodeId(source_node_id);
262 while let Some(source_ancestor) = source_stack.last() {
263 if source_node.parent == Some(*source_ancestor) {
264 break;
265 } else {
266 source_stack.pop();
267 self.pop_node();
268 }
269 }
270
271 source_stack.push(source_node_id);
272 self.move_node(source_node);
273 }
274
275 while !source_stack.is_empty() {
276 source_stack.pop();
277 self.pop_node();
278 }
279
280 ReusedSubtree {
281 old_range,
282 new_range,
283 }
284 }
285
286 pub fn clear_pending_keystrokes(&mut self) {
287 self.keystroke_matchers.clear();
288 }
289
290 /// Preserve keystroke matchers from previous frames to support multi-stroke
291 /// bindings across multiple frames.
292 pub fn preserve_pending_keystrokes(&mut self, old_tree: &mut Self, focus_id: Option<FocusId>) {
293 if let Some(node_id) = focus_id.and_then(|focus_id| self.focusable_node_id(focus_id)) {
294 let dispatch_path = self.dispatch_path(node_id);
295
296 self.context_stack.clear();
297 for node_id in dispatch_path {
298 let node = self.node(node_id);
299 if let Some(context) = node.context.clone() {
300 self.context_stack.push(context);
301 }
302
303 if let Some((context_stack, matcher)) = old_tree
304 .keystroke_matchers
305 .remove_entry(self.context_stack.as_slice())
306 {
307 self.keystroke_matchers.insert(context_stack, matcher);
308 }
309 }
310 }
311 }
312
313 pub fn on_key_event(&mut self, listener: KeyListener) {
314 self.active_node().key_listeners.push(listener);
315 }
316
317 pub fn on_modifiers_changed(&mut self, listener: ModifiersChangedListener) {
318 self.active_node()
319 .modifiers_changed_listeners
320 .push(listener);
321 }
322
323 pub fn on_action(
324 &mut self,
325 action_type: TypeId,
326 listener: Rc<dyn Fn(&dyn Any, DispatchPhase, &mut WindowContext)>,
327 ) {
328 self.active_node()
329 .action_listeners
330 .push(DispatchActionListener {
331 action_type,
332 listener,
333 });
334 }
335
336 pub fn focus_contains(&self, parent: FocusId, child: FocusId) -> bool {
337 if parent == child {
338 return true;
339 }
340
341 if let Some(parent_node_id) = self.focusable_node_ids.get(&parent) {
342 let mut current_node_id = self.focusable_node_ids.get(&child).copied();
343 while let Some(node_id) = current_node_id {
344 if node_id == *parent_node_id {
345 return true;
346 }
347 current_node_id = self.nodes[node_id.0].parent;
348 }
349 }
350 false
351 }
352
353 pub fn available_actions(&self, target: DispatchNodeId) -> Vec<Box<dyn Action>> {
354 let mut actions = Vec::<Box<dyn Action>>::new();
355 for node_id in self.dispatch_path(target) {
356 let node = &self.nodes[node_id.0];
357 for DispatchActionListener { action_type, .. } in &node.action_listeners {
358 if let Err(ix) = actions.binary_search_by_key(action_type, |a| a.as_any().type_id())
359 {
360 // Intentionally silence these errors without logging.
361 // If an action cannot be built by default, it's not available.
362 let action = self.action_registry.build_action_type(action_type).ok();
363 if let Some(action) = action {
364 actions.insert(ix, action);
365 }
366 }
367 }
368 }
369 actions
370 }
371
372 pub fn is_action_available(&self, action: &dyn Action, target: DispatchNodeId) -> bool {
373 for node_id in self.dispatch_path(target) {
374 let node = &self.nodes[node_id.0];
375 if node
376 .action_listeners
377 .iter()
378 .any(|listener| listener.action_type == action.as_any().type_id())
379 {
380 return true;
381 }
382 }
383 false
384 }
385
386 pub fn bindings_for_action(
387 &self,
388 action: &dyn Action,
389 context_stack: &[KeyContext],
390 ) -> Vec<KeyBinding> {
391 let keymap = self.keymap.borrow();
392 keymap
393 .bindings_for_action(action)
394 .filter(|binding| {
395 for i in 0..context_stack.len() {
396 let context = &context_stack[0..=i];
397 if keymap.binding_enabled(binding, context) {
398 return true;
399 }
400 }
401 false
402 })
403 .cloned()
404 .collect()
405 }
406
407 // dispatch_key pushes the next keystroke into any key binding matchers.
408 // any matching bindings are returned in the order that they should be dispatched:
409 // * First by length of binding (so if you have a binding for "b" and "ab", the "ab" binding fires first)
410 // * Secondly by depth in the tree (so if Editor has a binding for "b" and workspace a
411 // binding for "b", the Editor action fires first).
412 pub fn dispatch_key(
413 &mut self,
414 keystroke: &Keystroke,
415 dispatch_path: &SmallVec<[DispatchNodeId; 32]>,
416 ) -> KeymatchResult {
417 let mut bindings = SmallVec::<[KeyBinding; 1]>::new();
418 let mut pending = false;
419
420 let mut context_stack: SmallVec<[KeyContext; 4]> = SmallVec::new();
421 for node_id in dispatch_path {
422 let node = self.node(*node_id);
423
424 if let Some(context) = node.context.clone() {
425 context_stack.push(context);
426 }
427 }
428
429 while !context_stack.is_empty() {
430 let keystroke_matcher = self
431 .keystroke_matchers
432 .entry(context_stack.clone())
433 .or_insert_with(|| KeystrokeMatcher::new(self.keymap.clone()));
434
435 let result = keystroke_matcher.match_keystroke(keystroke, &context_stack);
436 if result.pending && !pending && !bindings.is_empty() {
437 context_stack.pop();
438 continue;
439 }
440
441 pending = result.pending || pending;
442 for new_binding in result.bindings {
443 match bindings
444 .iter()
445 .position(|el| el.keystrokes.len() < new_binding.keystrokes.len())
446 {
447 Some(idx) => {
448 bindings.insert(idx, new_binding);
449 }
450 None => bindings.push(new_binding),
451 }
452 }
453 context_stack.pop();
454 }
455
456 KeymatchResult { bindings, pending }
457 }
458
459 pub fn has_pending_keystrokes(&self) -> bool {
460 self.keystroke_matchers
461 .iter()
462 .any(|(_, matcher)| matcher.has_pending_keystrokes())
463 }
464
465 pub fn dispatch_path(&self, target: DispatchNodeId) -> SmallVec<[DispatchNodeId; 32]> {
466 let mut dispatch_path: SmallVec<[DispatchNodeId; 32]> = SmallVec::new();
467 let mut current_node_id = Some(target);
468 while let Some(node_id) = current_node_id {
469 dispatch_path.push(node_id);
470 current_node_id = self.nodes[node_id.0].parent;
471 }
472 dispatch_path.reverse(); // Reverse the path so it goes from the root to the focused node.
473 dispatch_path
474 }
475
476 pub fn focus_path(&self, focus_id: FocusId) -> SmallVec<[FocusId; 8]> {
477 let mut focus_path: SmallVec<[FocusId; 8]> = SmallVec::new();
478 let mut current_node_id = self.focusable_node_ids.get(&focus_id).copied();
479 while let Some(node_id) = current_node_id {
480 let node = self.node(node_id);
481 if let Some(focus_id) = node.focus_id {
482 focus_path.push(focus_id);
483 }
484 current_node_id = node.parent;
485 }
486 focus_path.reverse(); // Reverse the path so it goes from the root to the focused node.
487 focus_path
488 }
489
490 pub fn view_path(&self, view_id: EntityId) -> SmallVec<[EntityId; 8]> {
491 let mut view_path: SmallVec<[EntityId; 8]> = SmallVec::new();
492 let mut current_node_id = self.view_node_ids.get(&view_id).copied();
493 while let Some(node_id) = current_node_id {
494 let node = self.node(node_id);
495 if let Some(view_id) = node.view_id {
496 view_path.push(view_id);
497 }
498 current_node_id = node.parent;
499 }
500 view_path.reverse(); // Reverse the path so it goes from the root to the view node.
501 view_path
502 }
503
504 pub fn node(&self, node_id: DispatchNodeId) -> &DispatchNode {
505 &self.nodes[node_id.0]
506 }
507
508 fn active_node(&mut self) -> &mut DispatchNode {
509 let active_node_id = self.active_node_id().unwrap();
510 &mut self.nodes[active_node_id.0]
511 }
512
513 pub fn focusable_node_id(&self, target: FocusId) -> Option<DispatchNodeId> {
514 self.focusable_node_ids.get(&target).copied()
515 }
516
517 pub fn root_node_id(&self) -> DispatchNodeId {
518 debug_assert!(!self.nodes.is_empty());
519 DispatchNodeId(0)
520 }
521
522 pub fn active_node_id(&self) -> Option<DispatchNodeId> {
523 self.node_stack.last().copied()
524 }
525}
526
527#[cfg(test)]
528mod tests {
529 use std::{cell::RefCell, rc::Rc};
530
531 use crate::{Action, ActionRegistry, DispatchTree, KeyBinding, KeyContext, Keymap};
532
533 #[derive(PartialEq, Eq)]
534 struct TestAction;
535
536 impl Action for TestAction {
537 fn name(&self) -> &'static str {
538 "test::TestAction"
539 }
540
541 fn debug_name() -> &'static str
542 where
543 Self: ::std::marker::Sized,
544 {
545 "test::TestAction"
546 }
547
548 fn partial_eq(&self, action: &dyn Action) -> bool {
549 action
550 .as_any()
551 .downcast_ref::<Self>()
552 .map_or(false, |a| self == a)
553 }
554
555 fn boxed_clone(&self) -> std::boxed::Box<dyn Action> {
556 Box::new(TestAction)
557 }
558
559 fn as_any(&self) -> &dyn ::std::any::Any {
560 self
561 }
562
563 fn build(_value: serde_json::Value) -> anyhow::Result<Box<dyn Action>>
564 where
565 Self: Sized,
566 {
567 Ok(Box::new(TestAction))
568 }
569 }
570
571 #[test]
572 fn test_keybinding_for_action_bounds() {
573 let keymap = Keymap::new(vec![KeyBinding::new(
574 "cmd-n",
575 TestAction,
576 Some("ProjectPanel"),
577 )]);
578
579 let mut registry = ActionRegistry::default();
580
581 registry.load_action::<TestAction>();
582
583 let keymap = Rc::new(RefCell::new(keymap));
584
585 let tree = DispatchTree::new(keymap, Rc::new(registry));
586
587 let contexts = vec![
588 KeyContext::parse("Workspace").unwrap(),
589 KeyContext::parse("ProjectPanel").unwrap(),
590 ];
591
592 let keybinding = tree.bindings_for_action(&TestAction, &contexts);
593
594 assert!(keybinding[0].action.partial_eq(&TestAction))
595 }
596}