Fix (and then, use) the binary encoding to persist data

moor/example_web/lib/database/database.g.dart

@@ -187,10 +187,39 @@ class $TodoEntriesTable extends TodoEntries
   }
 }
 
+class HiddenEntryCountResult {
+  final int entries;
+  HiddenEntryCountResult({
+    this.entries,
+  });
+}
+
 abstract class _$Database extends GeneratedDatabase {
   _$Database(QueryExecutor e) : super(const SqlTypeSystem.withDefaults(), e);
   $TodoEntriesTable _todoEntries;
   $TodoEntriesTable get todoEntries => _todoEntries ??= $TodoEntriesTable(this);
+  HiddenEntryCountResult _rowToHiddenEntryCountResult(QueryRow row) {
+    return HiddenEntryCountResult(
+      entries: row.readInt('entries'),
+    );
+  }
+
+  Future<List<HiddenEntryCountResult>> hiddenEntryCount(
+      {@Deprecated('No longer needed with Moor 1.6 - see the changelog for details')
+          QueryEngine operateOn}) {
+    return (operateOn ?? this).customSelect(
+        'SELECT COUNT(*) - 20 AS entries FROM todo_entries WHERE done',
+        variables: []).then((rows) => rows.map(_rowToHiddenEntryCountResult).toList());
+  }
+
+  Stream<List<HiddenEntryCountResult>> watchHiddenEntryCount() {
+    return customSelectStream(
+            'SELECT COUNT(*) - 20 AS entries FROM todo_entries WHERE done',
+            variables: [],
+            readsFrom: {todoEntries})
+        .map((rows) => rows.map(_rowToHiddenEntryCountResult).toList());
+  }
+
   @override
   List<TableInfo> get allTables => [todoEntries];
 }

moor/lib/moor_web.dart

@@ -5,7 +5,6 @@
 library moor_web;
 
 import 'dart:async';
-import 'dart:convert';
 import 'dart:html';
 
 import 'package:meta/meta.dart';
@@ -13,9 +12,9 @@ import 'package:meta/dart2js.dart';
 import 'package:synchronized/synchronized.dart';
 
 import 'moor.dart';
+import 'src/web/binary_string_conversion.dart';
 import 'src/web/sql_js.dart';
 
 export 'moor.dart';
 
-part 'src/web/binary_string_conversion.dart';
 part 'src/web/web_db.dart';

moor/lib/src/web/binary_string_conversion.dart

@@ -1,18 +1,19 @@
-part of 'package:moor/moor_web.dart';
-/*
-const _bin2str = _BinaryStringConversion();
+import 'dart:convert';
+import 'dart:math' as math;
+import 'dart:typed_data';
 
-class _BinaryStringConversion extends Encoding {
+/// Converts [Uint8List]s to binary strings. Used internally by moor to store
+/// a database inside `window.localStorage`.
+const bin2str = _BinaryStringConversion();
+
+class _BinaryStringConversion extends Codec<Uint8List, String> {
   const _BinaryStringConversion();
 
   @override
-  Converter<List<int>, String> get decoder => const _Bin2String();
+  Converter<String, Uint8List> get decoder => const _String2Bin();
 
   @override
-  Converter<String, List<int>> get encoder => const _String2Bin();
-
-  @override
-  String get name => 'bin';
+  Converter<Uint8List, String> get encoder => const _Bin2String();
 }
 
 class _String2Bin extends Converter<String, Uint8List> {
@@ -24,22 +25,28 @@ class _String2Bin extends Converter<String, Uint8List> {
     final list = Uint8List(codeUnits.length);
 
     for (var i = 0; i < codeUnits.length; i++) {
-      list[i] = i;
+      list[i] = codeUnits[i];
     }
     return list;
   }
 }
 
-class _Bin2String extends Converter<List<int>, String> {
+class _Bin2String extends Converter<Uint8List, String> {
   const _Bin2String();
 
+  // There is a browser limit on the amount of chars one can give to
+  // String.fromCharCodes https://github.com/kripken/sql.js/wiki/Persisting-a-Modified-Database#save-a-database-to-a-string
+  final int _chunkSize = 0xffff;
+
   @override
-  String convert(List<int> input) {
+  String convert(Uint8List input) {
     final buffer = StringBuffer();
-    for (var byte in input) {
-      buffer.writeCharCode(byte);
+
+    for (var pos = 0; pos < input.length; pos += _chunkSize) {
+      final endPos = math.min(pos + _chunkSize, input.length);
+      buffer.write(String.fromCharCodes(input.sublist(pos, endPos)));
     }
+
     return buffer.toString();
   }
 }
-*/

moor/lib/src/web/web_db.dart

@@ -33,19 +33,17 @@ abstract class _DatabaseUser extends QueryExecutor {
     return await lock.synchronized(computation);
   }
 
-  // todo base64 works, but is very slow. Figure out why bin2str is broken
-
   Uint8List _restoreDb() {
     final raw = window.localStorage[_persistenceKey];
     if (raw != null) {
-      return base64.decode(raw);
+      return bin2str.decode(raw);
     }
     return null;
   }
 
   void _storeDb() {
     final data = _db.export();
-    final binStr = base64.encode(data);
+    final binStr = bin2str.encode(data);
     window.localStorage[_persistenceKey] = binStr;
   }
 

moor/test/web/binary_string_test.dart

@@ -0,0 +1,18 @@
+import 'dart:typed_data';
+
+import 'package:moor/src/web/binary_string_conversion.dart';
+import 'package:test_api/test_api.dart';
+
+void main() {
+  final data = Uint8List(256 * 2);
+  for (var i = 0; i < 256; i++) {
+    data[i] = i % 256;
+  }
+
+  test('converts binary data from and to strings', () {
+    final asStr = bin2str.encode(data);
+    final backToBin = bin2str.decode(asStr);
+
+    expect(backToBin, data);
+  });
+}