Migrate to null safety

analysis_options.yaml

@@ -48,7 +48,6 @@ linter:
     - always_put_required_named_parameters_first
     - always_require_non_null_named_parameters
     - annotate_overrides
-    - avoid_as
     - avoid_annotating_with_dynamic
     - avoid_classes_with_only_static_members
     - avoid_bool_literals_in_conditional_expressions

lib/src/convert/utf16.dart

@@ -1,7 +1,7 @@
 import 'dart:convert';
 import 'dart:core';
 
-import 'package:utf/utf.dart' as utf;
+import 'package:utf_convert/utf_convert.dart' as utf;
 
 abstract class UTF16 extends Encoding {
   List<int> get bom;
@@ -37,14 +37,14 @@ class _UTF16LEDecoder extends Converter<List<int>, String> {
   @override
   String convert(List<int> input) {
     final decoder = utf.Utf16leBytesToCodeUnitsDecoder(input);
-    return String.fromCharCodes(decoder.decodeRest());
+    return String.fromCharCodes(decoder.decodeRest().cast<int>());
   }
 }
 
 class _UTF16LEEncoder extends Converter<String, List<int>> {
   @override
   List<int> convert(String input) {
-    return utf.encodeUtf16le(input, true);
+    return utf.encodeUtf16le(input, true) as List<int>;
   }
 }
 
@@ -66,13 +66,13 @@ class _UTF16BEDecoder extends Converter<List<int>, String> {
   @override
   String convert(List<int> input) {
     final decoder = utf.Utf16beBytesToCodeUnitsDecoder(input);
-    return String.fromCharCodes(decoder.decodeRest());
+    return String.fromCharCodes(decoder.decodeRest().cast<int>());
   }
 }
 
 class _UTF16BEEncoder extends Converter<String, List<int>> {
   @override
   List<int> convert(String input) {
-    return utf.encodeUtf16be(input, true);
+    return utf.encodeUtf16be(input, true) as List<int>;
   }
 }

lib/src/frames/frame.dart

@@ -12,19 +12,19 @@ import 'id3v2/default_frame.dart';
 /// Abstract implementation of id3v2 frame
 abstract class Frame<T> {
   /// Encode [key] tag with [value] to bytearray
-  List<int> encode(T value, [String key]);
+  List<int> encode(T value, [String? key]);
 
   /// Decode byte [data] to frame data map
-  MapEntry<String, T> decode(List<int> data);
+  MapEntry<String, T>? decode(List<int> data);
 }
 
-class FrameFactory<T extends Frame> {
+class FrameFactory<T extends Frame?> {
   String version;
 
   // ignore: avoid_annotating_with_dynamic
-  Frame Function(dynamic entry) _frameGetter;
+  Frame? Function(dynamic entry) _frameGetter;
 
-  Frame defaultFrame;
+  Frame? defaultFrame;
 
   FrameFactory._internal(this.version, this._frameGetter, [this.defaultFrame]);
 
@@ -40,7 +40,7 @@ class FrameFactory<T extends Frame> {
     return FrameFactory._internal('0', (v) => null);
   }
 
-  T getFrame(entry) => _frameGetter(entry);
+  Frame? getFrame(entry) => _frameGetter(entry);
 }
 
 class FramesID3V23 extends FramesID3V24 {
@@ -55,7 +55,7 @@ class FramesID3V23 extends FramesID3V24 {
 
   @override
   Frame<T> _getFrame<T>(String tag) {
-    return _frames[tag] ?? DefaultFrame(tag, version: 3);
+    return _frames[tag] as Frame<T>? ?? DefaultFrame(tag, version: 3) as Frame<T>;
   }
 }
 
@@ -69,16 +69,16 @@ class FramesID3V24 {
       };
 
   Frame<T> _getFrame<T>(String tag) {
-    return _frames[tag] ?? DefaultFrame(tag);
+    return _frames[tag] as Frame<T>? ?? DefaultFrame(tag) as Frame<T>;
   }
 
   String getTagByPseudonym(String tag) {
     return consts.frameHeaderShortcutsID3V2_3_Rev.containsKey(tag)
-        ? consts.frameHeaderShortcutsID3V2_3_Rev[tag]
+        ? consts.frameHeaderShortcutsID3V2_3_Rev[tag]!
         : consts.framesHeaders.containsKey(tag) ? tag : 'TXXX';
   }
 
-  Frame<T> getFrame<T>(data) {
+  Frame<T>? getFrame<T>(data) {
     assert(data is List<int> || data is String);
 
     if (data is List<int>) {

lib/src/frames/id3v2/apic_frame.dart

@@ -83,14 +83,14 @@ class ApicFrame extends ID3V2Frame<AttachedPicture> {
     final imageData = data.sublist(startOfImageData);
 
     final extractedImageData = _imageExtractors.containsKey(mime)
-        ? _imageExtractors[mime]().parse(imageData)
+        ? _imageExtractors[mime]!().parse(imageData)
         : imageData;
 
     return AttachedPicture(mime, imageType, description, extractedImageData);
   }
 
   @override
-  List<int> encode(AttachedPicture value, [String key]) {
+  List<int> encode(AttachedPicture value, [String? key]) {
     final mimeEncoded = latin1.encode(value.mime);
     final descEncoded = utf8.encode(value.description);
 

lib/src/frames/id3v2/comm_frame.dart

@@ -42,7 +42,7 @@ class COMMFrame extends ID3V2Frame<Comment> {
   }
 
   @override
-  List<int> encode(Comment value, [String key]) {
+  List<int> encode(Comment value, [String? key]) {
     final enc = header?.encoding ?? utf8;
 
     return [

lib/src/frames/id3v2/default_frame.dart

@@ -13,7 +13,7 @@ class DefaultFrame extends ID3V2Frame<String> {
   }
 
   @override
-  List<int> encode(String value, [String key]) {
+  List<int> encode(String value, [String? key]) {
     final tag = getTagByPseudonym(frameTag);
 
     final vBytes = utf8.encode(value);

lib/src/frames/id3v2/id3v2_frame.dart

@@ -25,13 +25,13 @@ abstract class ID3V2Frame<T> implements Frame<T> {
 
   final int _version;
 
-  ID3V2FrameHeader _header;
-  ID3V2FrameHeader get header => _header;
+  ID3V2FrameHeader? _header;
+  ID3V2FrameHeader? get header => _header;
 
   ID3V2Frame(this._version);
 
   @override
-  MapEntry<String, T> decode(List<int> data) {
+  MapEntry<String, T>? decode(List<int> data) {
     final tag = latin1.decode(data.sublist(0, 4));
     if (!consts.framesHeaders.keys.contains(tag)) {
       return null;
@@ -46,27 +46,27 @@ abstract class ID3V2Frame<T> implements Frame<T> {
 
     _header = ID3V2FrameHeader(tag, size, encoding: encoding);
 
-    if (data.length < headerLength + _header?.length) {
+    if (data.length < headerLength + _header!.length) {
       _header =
           ID3V2FrameHeader(tag, data.length - headerLength, encoding: encoding);
     }
 
-    final body = data.sublist(headerLength + 1, headerLength + _header?.length);
+    final body = data.sublist(headerLength + 1, headerLength + _header!.length);
 
     return MapEntry<String, T>(
-        getTagPseudonym(_header.tag), decodeBody(body, encoding));
+        getTagPseudonym(_header!.tag), decodeBody(body, encoding));
   }
 
   T decodeBody(List<int> data, Encoding enc);
 
   @override
-  List<int> encode(T value, [String key]);
+  List<int> encode(T value, [String? key]);
 
   /// Returns size of frame in bytes
   List<int> frameSizeInBytes(int value) {
     assert(value <= 16777216);
 
-    final block = List<int>(4);
+    final block = List<int>.filled(4, 0);
     final sevenBitMask = 0x7f;
 
     block[0] = (value >> 21) & sevenBitMask;
@@ -79,13 +79,13 @@ abstract class ID3V2Frame<T> implements Frame<T> {
 
   String getTagByPseudonym(String tag) {
     return consts.frameHeaderShortcutsID3V2_3_Rev.containsKey(tag)
-        ? consts.frameHeaderShortcutsID3V2_3_Rev[tag]
+        ? consts.frameHeaderShortcutsID3V2_3_Rev[tag]!
         : tag;
   }
 
   String getTagPseudonym(String tag) {
     return consts.frameHeaderShortcutsID3V2_3.containsKey(tag)
-        ? consts.frameHeaderShortcutsID3V2_3[tag]
+        ? consts.frameHeaderShortcutsID3V2_3[tag]!
         : tag;
   }
 
@@ -133,7 +133,7 @@ abstract class ID3V2Frame<T> implements Frame<T> {
 
   int indexOfSplitPattern(List<int> list, List<int> pattern,
       [int initialOffset = 0]) {
-    for (var i = initialOffset ?? 0;
+    for (var i = initialOffset;
         i < list.length - pattern.length;
         i += pattern.length) {
       final l = list.sublist(i, i + pattern.length);
@@ -182,10 +182,10 @@ class ID3V2FrameHeader {
   String tag;
   int length;
 
-  Encoding encoding;
+  Encoding? encoding;
 
   // todo: implement futher
-  int flags;
+  int? flags;
 
   ID3V2FrameHeader(this.tag, this.length, {this.flags, this.encoding}) {
     assert(consts.framesHeaders.keys.contains(tag));

lib/src/frames/id3v2/txxx_frame.dart

@@ -42,11 +42,11 @@ class TXXXFrame extends ID3V2Frame<String> {
   @override
   String get frameTag => 'TXXX';
 
-  String _customTagName;
+  String? _customTagName;
 
   @override
   MapEntry<String, String> decode(List<int> data) {
-    final entry = super.decode(data);
+    final entry = super.decode(data)!;
     return MapEntry<String, String>(_customTagName ?? frameTag, entry.value);
   }
 
@@ -64,7 +64,7 @@ class TXXXFrame extends ID3V2Frame<String> {
   }
 
   @override
-  List<int> encode(String value, [String key]) {
+  List<int> encode(String value, [String? key]) {
     final body = utf8.encode('$key${utf8.decode([0x00])}$value');
     return [
       ...utf8.encode(frameTag),

lib/src/frames/id3v2/uslt_frame.dart

@@ -43,7 +43,7 @@ class USLTFrame extends ID3V2Frame<UnSyncLyric> {
   }
 
   @override
-  List<int> encode(UnSyncLyric value, [String key]) {
+  List<int> encode(UnSyncLyric value, [String? key]) {
     final enc = header?.encoding ?? utf8;
 
     return [

lib/src/frames/id3v2/wxxx_frame.dart

@@ -41,7 +41,7 @@ class WXXXFrame extends ID3V2Frame<WURL> {
   String get frameTag => 'WXXX';
 
   @override
-  List<int> encode(WURL value, [String key]) {
+  List<int> encode(WURL value, [String? key]) {
     final vBytes = [
       ...utf8.encode('${value.description}${utf8.decode([0x00])}'),
       ...latin1.encode(value.url)

lib/src/model/attached_picture.dart

@@ -50,7 +50,7 @@ class AttachedPicture implements KeyEntity<String> {
   /// Returns [String] representation of image type.
   ///
   /// eg. 'Band/Orchestra' or 'Cover (front)' etc...
-  String get imageType => _picturesType[imageTypeCode ?? 0x00];
+  String get imageType => _picturesType[imageTypeCode];
 
   AttachedPicture(
       this.mime, this.imageTypeCode, this.description, this.imageData);
@@ -68,6 +68,9 @@ class AttachedPicture implements KeyEntity<String> {
 
   @override
   bool operator ==(other) {
+    if (!(other is AttachedPicture)) {
+      return false;
+    }
     if (imageTypeCode != other.imageTypeCode) {
       return false;
     }
@@ -77,9 +80,6 @@ class AttachedPicture implements KeyEntity<String> {
     if (description != other.description) {
       return false;
     }
-    if (imageData == null && other.imageData == null) {
-      return true;
-    }
     if (imageData.length != other.imageData.length) {
       return false;
     }

lib/src/model/comment.dart

@@ -23,6 +23,9 @@ class Comment implements KeyEntity<String> {
 
   @override
   bool operator ==(other) {
+    if (!(other is Comment)) {
+      return false;
+    }
     if (lang != other.lang) {
       return false;
     }

lib/src/model/consts.dart

@@ -1,5 +1,5 @@
 /// Generes constants from id3v1.1 specification
-final id3v1generes = const <String>[
+final List<String> id3v1generes = const <String>[
   'Blues',
   'Classic Rock',
   'Country',

lib/src/model/lyrics.dart

@@ -23,6 +23,9 @@ class UnSyncLyric implements KeyEntity<String> {
 
   @override
   bool operator ==(other) {
+    if (!(other is UnSyncLyric)) {
+      return false;
+    }
     if (lang != other.lang) {
       return false;
     }

lib/src/model/tag.dart

@@ -1,16 +1,19 @@
 /// Class describes tag
 class Tag {
   /// Type of tag. At this time supports 'id3'
-  String type;
+  String? type;
 
   /// Version of tag. eg. '2.4.0' or '1.1'
-  String version;
+  String? version;
 
   /// The map of tags. Values are dynamic because it can be not only String.
-  Map<String, dynamic> tags;
+  late Map<String, dynamic> tags;
 
   @override
   bool operator ==(other) {
+    if (!(other is Tag)) {
+      return false;
+    }
     if (type != other.type) {
       return false;
     }

lib/src/model/wurl.dart

@@ -20,6 +20,9 @@ class WURL implements KeyEntity<String> {
 
   @override
   bool operator ==(other) {
+    if (!(other is WURL)) {
+      return false;
+    }
     if (description != other.description) {
       return false;
     }

lib/src/readers/id3v2.dart

@@ -67,23 +67,23 @@ class ID3V2Reader extends Reader {
     while (contin) {
       final fr = bytes.sublist(offset);
 
-      final frame = ff.getFrame(fr);
+      final frame = ff.getFrame(fr)! as ID3V2Frame;
       final m = frame.decode(fr);
 
       if (m?.key != null && m?.value != null) {
         if (m?.value is KeyEntity) {
-          if (tags[m.key] == null) {
+          if (tags[m!.key] == null) {
             tags[m.key] = {m.value.key: m.value};
           } else {
             tags[m.key][m.value.key] = m.value;
           }
         } else {
-          tags[m.key] = m.value;
+          tags[m!.key] = m.value;
         }
       }
 
-      offset = offset + _headerLength + (frame?.header?.length ?? 0);
-      contin = offset < size && (frame?.header?.length ?? 0) != 0;
+      offset = offset + _headerLength + (frame.header?.length ?? 0);
+      contin = offset < size && (frame.header?.length ?? 0) != 0;
     }
 
     return tags;