autocomplete: Add cache param to MentionAutocompleteQuery.testUser

Author: chrisbobbe

lib/model/autocomplete.dart

@@ -8,12 +8,11 @@ class MentionAutocompleteQuery {
 
   final List<String> _lowercaseWords;
 
-  bool testUser(User user) {
+  bool testUser(User user, AutocompleteDataCache cache) {
     // TODO test email too, not just name
     // TODO test with diacritics stripped, where appropriate
 
-    // TODO cache, elsewhere
-    final List<String> nameWords = user.fullName.toLowerCase().split(' ');
+    final List<String> nameWords = cache.nameWordsForUser(user);
 
     int nameWordsIndex = 0;
     int queryWordsIndex = 0;
@@ -40,3 +39,13 @@ class MentionAutocompleteQuery {
   @override
   int get hashCode => Object.hash('MentionAutocompleteQuery', raw);
 }
+
+class AutocompleteDataCache {
+  final Map<int, List<String>> _nameWordsByUser = {};
+  List<String> nameWordsForUser(User user) {
+    return _nameWordsByUser[user.userId] ??= user.fullName.toLowerCase().split(' ');
+  }
+  invalidateUser(int userId) {
+    _nameWordsByUser.remove(userId);
+  }
+}

test/model/autocomplete_test.dart

@@ -8,7 +8,8 @@ import '../example_data.dart' as eg;
 void main() {
   test('MentionAutocompleteQuery.testUser', () {
     doCheck(String rawQuery, User user, bool expected) {
-      final result = MentionAutocompleteQuery(rawQuery).testUser(user);
+      final result = MentionAutocompleteQuery(rawQuery)
+        .testUser(user, AutocompleteDataCache());
       expected ? check(result).isTrue() : check(result).isFalse();
     }