Add activateOnTypingDelay option

FEATURE: The new `activateOnTypingDelay` option allows control over the debounce
time before the completions are queried when the user types.

Closes #20

src/config.ts

@@ -7,6 +7,12 @@ export interface CompletionConfig {
   /// When enabled (defaults to true), autocompletion will start
   /// whenever the user types something that can be completed.
   activateOnTyping?: boolean
+  /// The amount of time to wait for further typing before querying
+  /// completion sources via
+  /// [`activateOnTyping`](#autocomplete.autocompletion^config.activateOnTyping).
+  /// Defaults to 100, which should be fine unless your completion
+  /// source is very slow and/or doesn't use `validFor`.
+  activateOnTypingDelay?: number
   /// By default, when completion opens, the first option is selected
   /// and can be confirmed with
   /// [`acceptCompletion`](#autocomplete.acceptCompletion). When this
@@ -82,6 +88,7 @@ export const completionConfig = Facet.define<CompletionConfig, Required<Completi
   combine(configs) {
     return combineConfig<Required<CompletionConfig>>(configs, {
       activateOnTyping: true,
+      activateOnTypingDelay: 100,
       selectOnOpen: true,
       override: null,
       closeOnBlur: true,

src/view.ts

@@ -72,6 +72,7 @@ export const completionPlugin = ViewPlugin.fromClass(class implements PluginValu
   debounceUpdate = -1
   running: RunningQuery[] = []
   debounceAccept = -1
+  pendingStart = false
   composing = CompositionState.None
 
   constructor(readonly view: EditorView) {
@@ -102,8 +103,10 @@ export const completionPlugin = ViewPlugin.fromClass(class implements PluginValu
     }
 
     if (this.debounceUpdate > -1) clearTimeout(this.debounceUpdate)
+    if (update.transactions.some(tr => tr.effects.some(e => e.is(startCompletionEffect)))) this.pendingStart = true
+    let delay = this.pendingStart ? 50 : update.state.facet(completionConfig).activateOnTypingDelay
     this.debounceUpdate = cState.active.some(a => a.state == State.Pending && !this.running.some(q => q.active.source == a.source))
-      ? setTimeout(() => this.startUpdate(), 50) : -1
+      ? setTimeout(() => this.startUpdate(), delay) : -1
 
     if (this.composing != CompositionState.None) for (let tr of update.transactions) {
       if (getUserEvent(tr) == "input")
@@ -115,6 +118,7 @@ export const completionPlugin = ViewPlugin.fromClass(class implements PluginValu
 
   startUpdate() {
     this.debounceUpdate = -1
+    this.pendingStart = false
     let {state} = this.view, cState = state.field(completionState)
     for (let active of cState.active) {
       if (active.state == State.Pending && !this.running.some(r => r.active.source == active.source))

test/webtest-autocomplete.ts

@@ -37,7 +37,10 @@ class Runner {
       state: EditorState.create({
         doc: spec.doc,
         selection,
-        extensions: [autocompletion({override: spec.sources, interactionDelay: 0, updateSyncTime: 40}), EditorState.allowMultipleSelections.of(true)]
+        extensions: [
+          autocompletion({override: spec.sources, interactionDelay: 0, updateSyncTime: 40, activateOnTypingDelay: 10}),
+          EditorState.allowMultipleSelections.of(true)
+        ]
       }),
       parent: document.querySelector("#workspace")! as HTMLElement,
       dispatchTransactions: trs => {