autocomplete [nfc]: Make query non-nullable on AutocompleteView

At first glance this appears to make a functional change: it causes
the search to begin as soon as the AutocompleteView is constructed,
rather than later when `query` is set to non-null.

But in fact the only times (outside tests) that we ultimately
construct an AutocompleteView are by calling an implementation of
AutocompleteField.initViewModel... and those call sites are
immediately followed by setting a non-null query.  So this is an
NFC commit after all.

Author: gnprice

lib/model/autocomplete.dart

@@ -184,37 +184,42 @@ class AutocompleteViewManager {
 /// and the [AutocompleteResult] subclass in `ResultT` describes the
 /// possible results that the user might choose in the autocomplete interaction.
 ///
+/// When an [AutocompleteView] is created, its constructor begins the search
+/// for results corresponding to the initial [query].
+/// The query may later be updated, causing a new search.
+///
 /// The owner of one of these objects must call [dispose] when the object
 /// will no longer be used, in order to free resources on the [PerAccountStore].
 ///
 /// Lifecycle:
-///  * Create an instance of a concrete subtype.
+///  * Create an instance of a concrete subtype, beginning a search
 ///  * Add listeners with [addListener].
-///  * Use the [query] setter to start a search for a query.
+///  * When the user edits the query, use the [query] setter to update the search.
 ///  * On reassemble, call [reassemble].
 ///  * When the object will no longer be used, call [dispose] to free
 ///    resources on the [PerAccountStore].
 abstract class AutocompleteView<QueryT extends AutocompleteQuery, ResultT extends AutocompleteResult> extends ChangeNotifier {
-  AutocompleteView({required this.store});
+  /// Construct a view-model for an autocomplete interaction,
+  /// and begin the search for the initial query.
+  AutocompleteView({required this.store, required QueryT query})
+      : _query = query {
+    _startSearch();
+  }
 
   final PerAccountStore store;
 
-  QueryT? get query => _query;
-  QueryT? _query;
-  set query(QueryT? query) {
+  QueryT get query => _query;
+  QueryT _query;
+  set query(QueryT query) {
     _query = query;
-    if (query != null) {
-      _startSearch();
-    }
+    _startSearch();
   }
 
   /// Called when the app is reassembled during debugging, e.g. for hot reload.
   ///
   /// This will redo the search from scratch for the current query, if any.
   void reassemble() {
-    if (_query != null) {
-      _startSearch();
-    }
+    _startSearch();
   }
 
   Iterable<ResultT> get results => _results;
@@ -271,8 +276,7 @@ abstract class AutocompleteView<QueryT extends AutocompleteQuery, ResultT extend
     required Iterable<T> candidates,
     required List<ResultT> results,
   }) async {
-    assert(_query != null);
-    final query = _query!;
+    final query = _query;
 
     final iterator = candidates.iterator;
     outer: while (true) {
@@ -295,16 +299,19 @@ abstract class AutocompleteView<QueryT extends AutocompleteQuery, ResultT extend
 class MentionAutocompleteView extends AutocompleteView<MentionAutocompleteQuery, MentionAutocompleteResult> {
   MentionAutocompleteView._({
     required super.store,
+    required super.query,
     required this.narrow,
     required this.sortedUsers,
   });
 
   factory MentionAutocompleteView.init({
     required PerAccountStore store,
     required Narrow narrow,
+    required MentionAutocompleteQuery query,
   }) {
     final view = MentionAutocompleteView._(
       store: store,
+      query: query,
       narrow: narrow,
       sortedUsers: _usersByRelevance(store: store, narrow: narrow),
     );
@@ -634,10 +641,19 @@ class UserMentionAutocompleteResult extends MentionAutocompleteResult {
 
 /// An autocomplete interaction for choosing a topic for a message.
 class TopicAutocompleteView extends AutocompleteView<TopicAutocompleteQuery, TopicAutocompleteResult> {
-  TopicAutocompleteView._({required super.store, required this.streamId});
+  TopicAutocompleteView._({
+    required super.store,
+    required super.query,
+    required this.streamId,
+  });
 
-  factory TopicAutocompleteView.init({required PerAccountStore store, required int streamId}) {
-    final view = TopicAutocompleteView._(store: store, streamId: streamId);
+  factory TopicAutocompleteView.init({
+    required PerAccountStore store,
+    required int streamId,
+    required TopicAutocompleteQuery query,
+  }) {
+    final view = TopicAutocompleteView._(
+      store: store, streamId: streamId, query: query);
     store.autocompleteViewManager.registerTopicAutocomplete(view);
     view._fetch();
     return view;
@@ -661,7 +677,7 @@ class TopicAutocompleteView extends AutocompleteView<TopicAutocompleteQuery, Top
     final result = await getStreamTopics(store.connection, streamId: streamId);
     _topics = result.topics.map((e) => e.name);
     _isFetching = false;
-    if (_query != null) return _startSearch();
+    return _startSearch();
   }
 
   @override

lib/widgets/autocomplete.dart

@@ -23,7 +23,7 @@ abstract class AutocompleteField<QueryT extends AutocompleteQuery, ResultT exten
 
   Widget buildItem(BuildContext context, int index, ResultT option);
 
-  AutocompleteView<QueryT, ResultT> initViewModel(BuildContext context);
+  AutocompleteView<QueryT, ResultT> initViewModel(BuildContext context, QueryT query);
 
   @override
   State<AutocompleteField<QueryT, ResultT>> createState() => _AutocompleteFieldState<QueryT, ResultT>();
@@ -32,18 +32,18 @@ abstract class AutocompleteField<QueryT extends AutocompleteQuery, ResultT exten
 class _AutocompleteFieldState<QueryT extends AutocompleteQuery, ResultT extends AutocompleteResult> extends State<AutocompleteField<QueryT, ResultT>> with PerAccountStoreAwareStateMixin<AutocompleteField<QueryT, ResultT>> {
   AutocompleteView<QueryT, ResultT>? _viewModel;
 
-  void _initViewModel() {
-    _viewModel = widget.initViewModel(context)
+  void _initViewModel(QueryT query) {
+    _viewModel = widget.initViewModel(context, query)
       ..addListener(_viewModelChanged);
   }
 
   void _handleControllerChange() {
-    final newAutocompleteIntent = widget.autocompleteIntent();
-    if (newAutocompleteIntent != null) {
+    final newQuery = widget.autocompleteIntent()?.query;
+    if (newQuery != null) {
       if (_viewModel == null) {
-        _initViewModel();
+        _initViewModel(newQuery);
       }
-      _viewModel!.query = newAutocompleteIntent.query;
+      _viewModel!.query = newQuery;
     } else {
       if (_viewModel != null) {
         _viewModel!.dispose(); // removes our listener
@@ -64,7 +64,7 @@ class _AutocompleteFieldState<QueryT extends AutocompleteQuery, ResultT extends
     if (_viewModel != null) {
       final query = _viewModel!.query;
       _viewModel!.dispose();
-      _initViewModel();
+      _initViewModel(query);
       _viewModel!.query = query;
     }
   }
@@ -162,9 +162,9 @@ class ComposeAutocomplete extends AutocompleteField<MentionAutocompleteQuery, Me
   AutocompleteIntent<MentionAutocompleteQuery>? autocompleteIntent() => controller.autocompleteIntent();
 
   @override
-  MentionAutocompleteView initViewModel(BuildContext context) {
+  MentionAutocompleteView initViewModel(BuildContext context, MentionAutocompleteQuery query) {
     final store = PerAccountStoreWidget.of(context);
-    return MentionAutocompleteView.init(store: store, narrow: narrow);
+    return MentionAutocompleteView.init(store: store, narrow: narrow, query: query);
   }
 
   void _onTapOption(BuildContext context, MentionAutocompleteResult option) {
@@ -238,9 +238,9 @@ class TopicAutocomplete extends AutocompleteField<TopicAutocompleteQuery, TopicA
   AutocompleteIntent<TopicAutocompleteQuery>? autocompleteIntent() => controller.autocompleteIntent();
 
   @override
-  TopicAutocompleteView initViewModel(BuildContext context) {
+  TopicAutocompleteView initViewModel(BuildContext context, TopicAutocompleteQuery query) {
     final store = PerAccountStoreWidget.of(context);
-    return TopicAutocompleteView.init(store: store, streamId: streamId);
+    return TopicAutocompleteView.init(store: store, streamId: streamId, query: query);
   }
 
   void _onTapOption(BuildContext context, TopicAutocompleteResult option) {

test/model/autocomplete_test.dart

@@ -175,11 +175,11 @@ void main() {
     const narrow = ChannelNarrow(1);
     final store = eg.store();
     await store.addUsers([eg.selfUser, eg.otherUser, eg.thirdUser]);
-    final view = MentionAutocompleteView.init(store: store, narrow: narrow);
 
+    final view = MentionAutocompleteView.init(store: store, narrow: narrow,
+      query: MentionAutocompleteQuery('Third'));
     bool done = false;
     view.addListener(() { done = true; });
-    view.query = MentionAutocompleteQuery('Third');
     await Future(() {});
     await Future(() {});
     check(done).isTrue();
@@ -193,12 +193,8 @@ void main() {
       const narrow = ChannelNarrow(1);
       final store = eg.store();
       await store.addUsers([eg.selfUser, eg.otherUser, eg.thirdUser]);
-      final view = MentionAutocompleteView.init(store: store, narrow: narrow);
 
       bool searchDone = false;
-      view.addListener(() {
-        searchDone = true;
-      });
 
       // Schedule a timer event with zero delay.
       // This stands in for a user interaction, or frame rendering timer,
@@ -210,9 +206,11 @@ void main() {
         check(searchDone).isFalse();
       });
 
-      view.query = MentionAutocompleteQuery('Third');
-      check(timerDone).isFalse();
-      check(searchDone).isFalse();
+      final view = MentionAutocompleteView.init(store: store, narrow: narrow,
+        query: MentionAutocompleteQuery('Third'));
+      view.addListener(() {
+        searchDone = true;
+      });
 
       binding.elapse(const Duration(seconds: 1));
 
@@ -230,11 +228,11 @@ void main() {
     for (int i = 1; i <= 2500; i++) {
       await store.addUser(eg.user(userId: i, email: 'user$i@example.com', fullName: 'User $i'));
     }
-    final view = MentionAutocompleteView.init(store: store, narrow: narrow);
 
     bool done = false;
+    final view = MentionAutocompleteView.init(store: store, narrow: narrow,
+      query: MentionAutocompleteQuery('User 2222'));
     view.addListener(() { done = true; });
-    view.query = MentionAutocompleteQuery('User 2222');
 
     await Future(() {});
     check(done).isFalse();
@@ -253,11 +251,11 @@ void main() {
     for (int i = 1; i <= 1500; i++) {
       await store.addUser(eg.user(userId: i, email: 'user$i@example.com', fullName: 'User $i'));
     }
-    final view = MentionAutocompleteView.init(store: store, narrow: narrow);
 
     bool done = false;
+    final view = MentionAutocompleteView.init(store: store, narrow: narrow,
+      query: MentionAutocompleteQuery('User 1111'));
     view.addListener(() { done = true; });
-    view.query = MentionAutocompleteQuery('User 1111');
 
     await Future(() {});
     check(done).isFalse();
@@ -288,11 +286,11 @@ void main() {
     for (int i = 1; i <= 2500; i++) {
       await store.addUser(eg.user(userId: i, email: 'user$i@example.com', fullName: 'User $i'));
     }
-    final view = MentionAutocompleteView.init(store: store, narrow: narrow);
 
     bool done = false;
+    final view = MentionAutocompleteView.init(store: store, narrow: narrow,
+      query: MentionAutocompleteQuery('User 110'));
     view.addListener(() { done = true; });
-    view.query = MentionAutocompleteQuery('User 110');
 
     await Future(() {});
     check(done).isFalse();
@@ -544,15 +542,17 @@ void main() {
 
     group('ranking across signals', () {
       void checkPrecedes(Narrow narrow, User userA, Iterable<User> usersB) {
-        final view = MentionAutocompleteView.init(store: store, narrow: narrow);
+        final view = MentionAutocompleteView.init(store: store, narrow: narrow,
+          query: MentionAutocompleteQuery(''));
         for (final userB in usersB) {
           check(view.debugCompareUsers(userA, userB)).isLessThan(0);
           check(view.debugCompareUsers(userB, userA)).isGreaterThan(0);
         }
       }
 
       void checkRankEqual(Narrow narrow, List<User> users) {
-        final view = MentionAutocompleteView.init(store: store, narrow: narrow);
+        final view = MentionAutocompleteView.init(store: store, narrow: narrow,
+          query: MentionAutocompleteQuery(''));
         for (int i = 0; i < users.length; i++) {
           for (int j = i + 1; j < users.length; j++) {
             check(view.debugCompareUsers(users[i], users[j])).equals(0);
@@ -669,21 +669,24 @@ void main() {
       test('CombinedFeedNarrow gives error', () async {
         await prepare(users: [eg.user(), eg.user()], messages: []);
         const narrow = CombinedFeedNarrow();
-        check(() => MentionAutocompleteView.init(store: store, narrow: narrow))
+        check(() => MentionAutocompleteView.init(store: store, narrow: narrow,
+                      query: MentionAutocompleteQuery('')))
           .throws<AssertionError>();
       });
 
       test('MentionsNarrow gives error', () async {
         await prepare(users: [eg.user(), eg.user()], messages: []);
         const narrow = MentionsNarrow();
-        check(() => MentionAutocompleteView.init(store: store, narrow: narrow))
+        check(() => MentionAutocompleteView.init(store: store, narrow: narrow,
+                      query: MentionAutocompleteQuery('')))
           .throws<AssertionError>();
       });
 
       test('StarredMessagesNarrow gives error', () async {
         await prepare(users: [eg.user(), eg.user()], messages: []);
         const narrow = StarredMessagesNarrow();
-        check(() => MentionAutocompleteView.init(store: store, narrow: narrow))
+        check(() => MentionAutocompleteView.init(store: store, narrow: narrow,
+                      query: MentionAutocompleteQuery('')))
           .throws<AssertionError>();
       });
     });
@@ -692,9 +695,9 @@ void main() {
       Future<Iterable<int>> getResults(
           Narrow narrow, MentionAutocompleteQuery query) async {
         bool done = false;
-        final view = MentionAutocompleteView.init(store: store, narrow: narrow);
+        final view = MentionAutocompleteView.init(store: store, narrow: narrow,
+          query: query);
         view.addListener(() { done = true; });
-        view.query = query;
         await Future(() {});
         check(done).isTrue();
         final results = view.results
@@ -777,13 +780,14 @@ void main() {
     final third = eg.getStreamTopicsEntry(maxId: 3, name: 'Third Topic');
     connection.prepare(json: GetStreamTopicsResult(
       topics: [first, second, third]).toJson());
+
     final view = TopicAutocompleteView.init(
       store: store,
-      streamId: eg.stream().streamId);
-
+      streamId: eg.stream().streamId,
+      query: TopicAutocompleteQuery('Third'));
     bool done = false;
     view.addListener(() { done = true; });
-    view.query = TopicAutocompleteQuery('Third');
+
     // those are here to wait for topics to be loaded
     await Future(() {});
     await Future(() {});
@@ -802,11 +806,10 @@ void main() {
 
     final view = TopicAutocompleteView.init(
       store: store,
-      streamId: eg.stream().streamId);
-
+      streamId: eg.stream().streamId,
+      query: TopicAutocompleteQuery('te'));
     bool done = false;
     view.addListener(() { done = true; });
-    view.query = TopicAutocompleteQuery('te');
 
     check(done).isFalse();
     await Future(() {});