Add a limit option for autocomplete results

src/autocomplete/AutocompleteProvider.tsx

@@ -93,7 +93,12 @@ export default class AutocompleteProvider {
         };
     }
 
-    async getCompletions(query: string, selection: ISelectionRange, force = false): Promise<ICompletion[]> {
+    async getCompletions(
+        query: string,
+        selection: ISelectionRange,
+        force = false,
+        limit = -1,
+    ): Promise<ICompletion[]> {
         return [];
     }
 

src/autocomplete/Autocompleter.ts

@@ -82,15 +82,24 @@ export default class Autocompleter {
         });
     }
 
-    async getCompletions(query: string, selection: ISelectionRange, force = false): Promise<IProviderCompletions[]> {
+    async getCompletions(
+        query: string,
+        selection: ISelectionRange,
+        force = false,
+        limit = -1,
+    ): Promise<IProviderCompletions[]> {
         /* Note: This intentionally waits for all providers to return,
          otherwise, we run into a condition where new completions are displayed
          while the user is interacting with the list, which makes it difficult
          to predict whether an action will actually do what is intended
         */
         // list of results from each provider, each being a list of completions or null if it times out
-        const completionsList: ICompletion[][] = await Promise.all(this.providers.map(provider => {
-            return timeout(provider.getCompletions(query, selection, force), null, PROVIDER_COMPLETION_TIMEOUT);
+        const completionsList: ICompletion[][] = await Promise.all(this.providers.map(async provider => {
+            return await timeout(
+                provider.getCompletions(query, selection, force, limit),
+                null,
+                PROVIDER_COMPLETION_TIMEOUT,
+            );
         }));
 
         // map then filter to maintain the index for the map-operation, for this.providers to line up

src/autocomplete/CommandProvider.tsx

@@ -38,7 +38,12 @@ export default class CommandProvider extends AutocompleteProvider {
         });
     }
 
-    async getCompletions(query: string, selection: ISelectionRange, force?: boolean): Promise<ICompletion[]> {
+    async getCompletions(
+        query: string,
+        selection: ISelectionRange,
+        force?: boolean,
+        limit = -1,
+    ): Promise<ICompletion[]> {
         const {command, range} = this.getCurrentCommand(query, selection);
         if (!command) return [];
 
@@ -55,10 +60,11 @@ export default class CommandProvider extends AutocompleteProvider {
         } else {
             if (query === '/') {
                 // If they have just entered `/` show everything
+                // We exclude the limit on purpose to have a comprehensive list
                 matches = Commands;
             } else {
                 // otherwise fuzzy match against all of the fields
-                matches = this.matcher.match(command[1]);
+                matches = this.matcher.match(command[1], limit);
             }
         }
 

src/autocomplete/CommunityProvider.tsx

@@ -50,7 +50,12 @@ export default class CommunityProvider extends AutocompleteProvider {
         });
     }
 
-    async getCompletions(query: string, selection: ISelectionRange, force = false): Promise<ICompletion[]> {
+    async getCompletions(
+        query: string,
+        selection: ISelectionRange,
+        force = false,
+        limit = -1,
+    ): Promise<ICompletion[]> {
         const BaseAvatar = sdk.getComponent('views.avatars.BaseAvatar');
 
         // Disable autocompletions when composing commands because of various issues
@@ -81,7 +86,7 @@ export default class CommunityProvider extends AutocompleteProvider {
             this.matcher.setObjects(groups);
 
             const matchedString = command[0];
-            completions = this.matcher.match(matchedString);
+            completions = this.matcher.match(matchedString, limit);
             completions = sortBy(completions, [
                 (c) => score(matchedString, c.groupId),
                 (c) => c.groupId.length,

src/autocomplete/DuckDuckGoProvider.tsx

@@ -36,7 +36,12 @@ export default class DuckDuckGoProvider extends AutocompleteProvider {
          + `&format=json&no_redirect=1&no_html=1&t=${encodeURIComponent(REFERRER)}`;
     }
 
-    async getCompletions(query: string, selection: ISelectionRange, force= false): Promise<ICompletion[]> {
+    async getCompletions(
+        query: string,
+        selection: ISelectionRange,
+        force = false,
+        limit = -1,
+    ): Promise<ICompletion[]> {
         const {command, range} = this.getCurrentCommand(query, selection);
         if (!query || !command) {
             return [];
@@ -46,7 +51,8 @@ export default class DuckDuckGoProvider extends AutocompleteProvider {
             method: 'GET',
         });
         const json = await response.json();
-        const results = json.Results.map((result) => {
+        const maxLength = limit > -1 ? limit : json.Results.length;
+        const results = json.Results.slice(0, maxLength).map((result) => {
             return {
                 completion: result.Text,
                 component: (

src/autocomplete/EmojiProvider.tsx

@@ -84,7 +84,12 @@ export default class EmojiProvider extends AutocompleteProvider {
         });
     }
 
-    async getCompletions(query: string, selection: ISelectionRange, force?: boolean): Promise<ICompletion[]> {
+    async getCompletions(
+        query: string,
+        selection: ISelectionRange,
+        force?: boolean,
+        limit = -1,
+    ): Promise<ICompletion[]> {
         if (!SettingsStore.getValue("MessageComposerInput.suggestEmoji")) {
             return []; // don't give any suggestions if the user doesn't want them
         }
@@ -93,7 +98,7 @@ export default class EmojiProvider extends AutocompleteProvider {
         const {command, range} = this.getCurrentCommand(query, selection);
         if (command) {
             const matchedString = command[0];
-            completions = this.matcher.match(matchedString);
+            completions = this.matcher.match(matchedString, limit);
 
             // Do second match with shouldMatchWordsOnly in order to match against 'name'
             completions = completions.concat(this.nameMatcher.match(matchedString));

src/autocomplete/NotifProvider.tsx

@@ -33,7 +33,12 @@ export default class NotifProvider extends AutocompleteProvider {
         this.room = room;
     }
 
-    async getCompletions(query: string, selection: ISelectionRange, force= false): Promise<ICompletion[]> {
+    async getCompletions(
+        query: string,
+        selection: ISelectionRange,
+        force = false,
+        limit = -1,
+    ): Promise<ICompletion[]> {
         const RoomAvatar = sdk.getComponent('views.avatars.RoomAvatar');
 
         const client = MatrixClientPeg.get();

src/autocomplete/QueryMatcher.ts

@@ -87,7 +87,7 @@ export default class QueryMatcher<T extends Object> {
         }
     }
 
-    match(query: string): T[] {
+    match(query: string, limit = -1): T[] {
         query = this.processQuery(query);
         if (this._options.shouldMatchWordsOnly) {
             query = query.replace(/[^\w]/g, '');
@@ -129,7 +129,10 @@ export default class QueryMatcher<T extends Object> {
         });
 
         // Now map the keys to the result objects. Also remove any duplicates.
-        return uniq(matches.map((match) => match.object));
+        const dedupped = uniq(matches.map((match) => match.object));
+        const maxLength = limit === -1 ? dedupped.length : limit;
+
+        return dedupped.slice(0, maxLength);
     }
 
     private processQuery(query: string): string {

src/autocomplete/RoomProvider.tsx

@@ -58,7 +58,12 @@ export default class RoomProvider extends AutocompleteProvider {
         });
     }
 
-    async getCompletions(query: string, selection: ISelectionRange, force = false): Promise<ICompletion[]> {
+    async getCompletions(
+        query: string,
+        selection: ISelectionRange,
+        force = false,
+        limit = -1,
+    ): Promise<ICompletion[]> {
         const RoomAvatar = sdk.getComponent('views.avatars.RoomAvatar');
 
         const client = MatrixClientPeg.get();
@@ -90,7 +95,7 @@ export default class RoomProvider extends AutocompleteProvider {
 
             this.matcher.setObjects(matcherObjects);
             const matchedString = command[0];
-            completions = this.matcher.match(matchedString);
+            completions = this.matcher.match(matchedString, limit);
             completions = sortBy(completions, [
                 (c) => score(matchedString, c.displayedAlias),
                 (c) => c.displayedAlias.length,

src/autocomplete/UserProvider.tsx

@@ -102,7 +102,12 @@ export default class UserProvider extends AutocompleteProvider {
         this.users = null;
     };
 
-    async getCompletions(rawQuery: string, selection: ISelectionRange, force = false): Promise<ICompletion[]> {
+    async getCompletions(
+        rawQuery: string,
+        selection: ISelectionRange,
+        force = false,
+        limit = -1,
+    ): Promise<ICompletion[]> {
         const MemberAvatar = sdk.getComponent('views.avatars.MemberAvatar');
 
         // lazy-load user list into matcher
@@ -118,7 +123,7 @@ export default class UserProvider extends AutocompleteProvider {
         if (fullMatch && fullMatch !== '@') {
             // Don't include the '@' in our search query - it's only used as a way to trigger completion
             const query = fullMatch.startsWith('@') ? fullMatch.substring(1) : fullMatch;
-            completions = this.matcher.match(query).map((user) => {
+            completions = this.matcher.match(query, limit).map((user) => {
                 const displayName = (user.name || user.userId || '');
                 return {
                     // Length of completion should equal length of text in decorator. draft-js

src/components/views/rooms/Autocomplete.tsx

@@ -26,6 +26,7 @@ import Autocompleter from '../../../autocomplete/Autocompleter';
 import {replaceableComponent} from "../../../utils/replaceableComponent";
 
 const COMPOSER_SELECTED = 0;
+const MAX_PROVIDER_MATCHES = 20;
 
 export const generateCompletionDomId = (number) => `mx_Autocomplete_Completion_${number}`;
 
@@ -136,7 +137,7 @@ export default class Autocomplete extends React.PureComponent<IProps, IState> {
 
     processQuery(query: string, selection: ISelectionRange) {
         return this.autocompleter.getCompletions(
-            query, selection, this.state.forceComplete,
+            query, selection, this.state.forceComplete, MAX_PROVIDER_MATCHES,
         ).then((completions) => {
             // Only ever process the completions for the most recent query being processed
             if (query !== this.queryRequested) {