Fixed tokenisation, updated format function

Author: tomc128

v2/BooleanExpressionParser/.vscode/launch.json

@@ -11,8 +11,7 @@
                 "A.B",
                 "A+B",
                 "!(A+B+C)",
-                "T+F+F.F",
-                "!A+B"
+                "((A.B&C) OR A) AND (NOT B + !C)"
             ],
             "cwd": "${workspaceFolder}",
             "console": "integratedTerminal", // enables input (instead of internalConsole)

v2/BooleanExpressionParser/Formatter.cs

@@ -4,48 +4,15 @@ namespace BooleanExpressionParser;
 
 class Formatter
 {
-    public static string FormatAstAsInfix(Node root)
+    public static string FormatInfixTokens(IEnumerable<Token> tokens)
     {
         var sb = new StringBuilder();
 
-        void Visit(Node node)
-        {
-            switch (node)
-            {
-                case AndOperatorNode op:
-                    VisitAndWrap(op.Left);
-                    sb.Append(" AND ");
-                    VisitAndWrap(op.Right!);
-                    break;
-
-                case OrOperatorNode op:
-                    VisitAndWrap(op.Left);
-                    sb.Append(" OR ");
-                    VisitAndWrap(op.Right!);
-                    break;
-
-                case NotOperatorNode op:
-                    sb.Append($"NOT (");
-                    Visit(op.Left);
-                    sb.Append(")");
-                    break;
-
-                case VariableNode var:
-                    sb.Append(var.Name);
-                    break;
-
-            }
-        }
-
-        void VisitAndWrap(Node node)
+        foreach (var token in tokens)
         {
-            if (node is AndOperatorNode || node is OrOperatorNode) sb.Append("(");
-            Visit(node);
-            if (node is AndOperatorNode || node is OrOperatorNode) sb.Append(")");
+            sb.Append(token.ToString());
         }
 
-        Visit(root);
-
         return sb.ToString();
     }
 

v2/BooleanExpressionParser/Parser.cs

@@ -94,7 +94,10 @@ public Ast GrowAst(IEnumerable<Token> tokens)
             }
         }
 
-        if (stack.Count != 1) throw new Exception("Expression invalid - stack not empty");
+        if (stack.Count != 1)
+        {
+            throw new Exception($"Expression invalid - stack not empty. Stack: {String.Join(", ", stack)}");
+        }
 
         var root = stack.Pop();
 

v2/BooleanExpressionParser/Program.cs

@@ -12,17 +12,17 @@ static void Main(params string[] args)
 
         foreach (var expression in args)
         {
-            var trimmed = expression.Replace(" ", "");
-            var tokeniser = new Tokeniser(trimmed);
+            var tokeniser = new Tokeniser(expression);
             var infixTokens = tokeniser.Tokenise();
 
             var parser = new Parser();
             var prefixTokens = parser.ParseTokens(infixTokens);
-            var ast = parser.GrowAst(prefixTokens);
 
             Console.WriteLine($"Expression: {expression}");
-            Console.WriteLine($"Infix: {Formatter.FormatAstAsInfix(ast.Root)}");
             Console.WriteLine($"Prefix: {Formatter.FormatPrefixTokens(prefixTokens)}");
+            Console.WriteLine($"Infix: {Formatter.FormatInfixTokens(infixTokens)}");
+
+            var ast = parser.GrowAst(prefixTokens);
 
             var evaluator = new Evaluator(ast);
             var table = evaluator.EvaluateAll();