refactor: high-level loops

lib/encryption/cross_signing.dart

@@ -115,19 +115,11 @@ class CrossSigning {
     ]);
   }
 
-  bool signable(List<SignableKey> keys) {
-    for (final key in keys) {
-      if (key is CrossSigningKey && key.usage.contains('master')) {
-        return true;
-      }
-      if (key.userId == client.userID &&
-          (key is DeviceKeys) &&
-          key.identifier != client.deviceID) {
-        return true;
-      }
-    }
-    return false;
-  }
+  bool signable(List<SignableKey> keys) => keys.any((key) =>
+      key is CrossSigningKey && key.usage.contains('master') ||
+      key is DeviceKeys &&
+          key.userId == client.userID &&
+          key.identifier != client.deviceID);
 
   Future<void> sign(List<SignableKey> keys) async {
     Uint8List selfSigningKey;

lib/encryption/key_verification_manager.dart

@@ -42,9 +42,7 @@ class KeyVerificationManager {
         entriesToDispose.add(entry.key);
       }
     }
-    for (final k in entriesToDispose) {
-      _requests.remove(k);
-    }
+    entriesToDispose.forEach(_requests.remove);
   }
 
   void addRequest(KeyVerification request) {

lib/encryption/utils/key_verification.dart

@@ -74,18 +74,8 @@ enum KeyVerificationState {
 
 enum KeyVerificationMethod { emoji, numbers }
 
-List<String> _intersect(List<String> a, List<dynamic> b) {
-  if (b == null || a == null) {
-    return [];
-  }
-  final res = <String>[];
-  for (final v in a) {
-    if (b.contains(v)) {
-      res.add(v);
-    }
-  }
-  return res;
-}
+List<String> _intersect(List<String> a, List<dynamic> b) =>
+    (b == null || a == null) ? [] : a.where(b.contains).toList();
 
 List<int> _bytesToInt(Uint8List bytes, int totalBits) {
   final ret = <int>[];

lib/src/client.dart

@@ -249,13 +249,11 @@ class Client extends MatrixApi {
     if (accountData['m.direct'] != null &&
         accountData['m.direct'].content[userId] is List<dynamic> &&
         accountData['m.direct'].content[userId].length > 0) {
-      final potentialRooms = <Room>{};
-      for (final roomId in accountData['m.direct'].content[userId]) {
-        final room = getRoomById(roomId);
-        if (room != null && room.membership == Membership.join) {
-          potentialRooms.add(room);
-        }
-      }
+      final potentialRooms = accountData['m.direct']
+          .content[userId]
+          .cast<String>()
+          .map(getRoomById)
+          .where((room) => room != null && room.membership == Membership.join);
       if (potentialRooms.isNotEmpty) {
         return potentialRooms
             .fold(

lib/src/event.dart

@@ -295,14 +295,11 @@ class Event extends MatrixEvent {
   /// Returns a list of [Receipt] instances for this event.
   List<Receipt> get receipts {
     if (!(room.roomAccountData.containsKey('m.receipt'))) return [];
-    final receiptsList = <Receipt>[];
-    for (final entry in room.roomAccountData['m.receipt'].content.entries) {
-      if (entry.value['event_id'] == eventId) {
-        receiptsList.add(Receipt(room.getUserByMXIDSync(entry.key),
-            DateTime.fromMillisecondsSinceEpoch(entry.value['ts'])));
-      }
-    }
-    return receiptsList;
+    return room.roomAccountData['m.receipt'].content.entries
+        .where((entry) => entry.value['event_id'] == eventId)
+        .map((entry) => Receipt(room.getUserByMXIDSync(entry.key),
+            DateTime.fromMillisecondsSinceEpoch(entry.value['ts'])))
+        .toList();
   }
 
   /// Removes this event if the status is < 1. This event will just be removed

lib/src/room.dart

@@ -285,9 +285,8 @@ class Room {
     // perfect, it is only used for the room preview in the room list and sorting
     // said room list, so it should be good enough.
     var lastTime = DateTime.fromMillisecondsSinceEpoch(0);
-    final lastEvents = <Event>[
-      for (var type in client.roomPreviewLastEvents) getState(type)
-    ]..removeWhere((e) => e == null);
+    final lastEvents =
+        client.roomPreviewLastEvents.map(getState).where((e) => e != null);
 
     var lastEvent = lastEvents.isEmpty
         ? null
@@ -375,12 +374,10 @@ class Room {
       }
     }
     if (heroes.isNotEmpty) {
-      var displayname = '';
-      for (final hero in heroes) {
-        if (hero.isEmpty) continue;
-        displayname += getUserByMXIDSync(hero).calcDisplayname() + ', ';
-      }
-      return displayname.substring(0, displayname.length - 2);
+      return heroes
+          .where((hero) => hero.isNotEmpty)
+          .map((hero) => getUserByMXIDSync(hero).calcDisplayname())
+          .join(', ');
     }
     if (membership == Membership.invite &&
         getState(EventTypes.RoomMember, client.userID) != null) {