Initial public commit

lib/logic/common/json_prefs_file.dart

@@ -0,0 +1,19 @@
+import 'dart:convert';
+
+import 'package:shared_preferences/shared_preferences.dart';
+
+class JsonPrefsFile {
+  JsonPrefsFile(this.name);
+  final String name;
+
+  Future<Map<String, dynamic>> load() async {
+    final p = (await SharedPreferences.getInstance()).getString(name);
+    //print('loaded: $p');
+    return Map<String, dynamic>.from(jsonDecode(p ?? '{}'));
+  }
+
+  Future<void> save(Map<String, dynamic> data) async {
+    //print('saving $data');
+    await (await SharedPreferences.getInstance()).setString(name, jsonEncode(data));
+  }
+}