refactor to use cells with formats

README.md

@@ -7,7 +7,7 @@
 [![GitHub Stars](https://img.shields.io/github/stars/sjhorn/visicalc_engine.svg)](https://github.com/sjhorn/visicalc_engine/stargazers)
 ![GitHub License](https://img.shields.io/github/license/sjhorn/visicalc_engine)
 
-This package implements a clone of the VisiCalc spreadsheet engine in a dart library that works by parsing the stringw of cells and calculating the result considering references to other cells.
+This package implements a clone of the VisiCalc spreadsheet engine in a dart library that works by parsing the strings of cells (Map<A1,String>) and calculating the result considering references to other cells.
 
 The screenshot below shows the original user interface of Visicalc made by [Dan Bricklin and Bob Frankston](http://danbricklin.com/visicalc.htm).
 ![VisiCalc Logo from Wikipedia](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Visicalc_logo.svg/320px-Visicalc_logo.svg.png)

example/example.dart

@@ -3,29 +3,31 @@ import 'package:visicalc_engine/visicalc_engine.dart';
 
 void main(List<String> arguments) {
   final sheet = {
-    'A1'.a1: '-12.2',
+    'A1'.a1: '/FR-12.2',
     'A2'.a1: '(a5+45)',
-    'A3'.a1: '13',
+    'A3'.a1: '/F*13',
     'A4'.a1: '+A2+A5-A6',
     'A5'.a1: '-A3/2+2',
-    'A6'.a1: '.23*2',
+    'A6'.a1: '/F\$.23*2',
     'B1'.a1: 'A1+A3*3',
     'B2'.a1: '(A1+A3)*3',
     'B3'.a1: '12.23e-12',
     'B4'.a1: '.23e12',
-    'B5'.a1: 'b4',
+    'B5'.a1: '/FRb4',
     'B6'.a1: 'b2',
     'B7'.a1: '@sum(a1...b6)',
+    'D13'.a1: 'b2',
   };
-  final worksheet = VisicalcEngine(sheet, parseErrorThrows: true);
-  for (final a1 in worksheet) {
-    print('$a1: ${worksheet[a1]}');
-  }
+  final worksheet = Engine(sheet, parseErrorThrows: true);
+  print(worksheet);
 
   // Change cell
   var b5 = worksheet["B5".a1];
   print('B5 formula was ${b5?.formulaType?.asFormula} = $b5');
-  print('Seeting to a1');
+  print('Now setting B5 to formula a1');
   worksheet['B5'.a1] = 'a1';
+
+  b5 = worksheet["B5".a1];
   print('Now B5 formula is ${b5?.formulaType?.asFormula} = $b5');
+  print(worksheet);
 }