removed "equation" field from PeverseNotationSolver because it is not really used and made this class static

Evil Calculator/EquationManager.cs

@@ -3,7 +3,6 @@
     class EquationManager
     {
         private static readonly HashSet<string> _operators = new() { "+", "-", "*", "/", "^", "√" };
-        private ReverseNotationSolver reverseNotationSolver = new();
 
         List<Token> equation = new();
         string currentOperand = "";
@@ -145,7 +144,7 @@
             {
                 if (currentOperand != "") equation.Add(new Token(Token.TokenType.Operand, currentOperand));
                 buttonEquals.Text = "#";
-                currentOperand = reverseNotationSolver.Solve(equation);
+                currentOperand = ReverseNotationSolver.Solve(equation);
                 UpdateLabels();
             }
         }

Evil Calculator/ReverseNotattionSolver.cs

@@ -1,57 +1,55 @@
 namespace Lunar.Evil_Calculator
 {
-    internal class ReverseNotationSolver
+    internal static class ReverseNotationSolver
     {
-        List<Token> equation = new();
+        private static List<Token> ToReverseNotation(List<Token> equation)
-
-        public string ToReverseNotation(List<Token> equation)
         {
-            List<Token> TEMP = new List<Token>();
+            List<Token> reversedEquation = new List<Token>();
-            Stack<Token> OPERATORS = new Stack<Token>();
+            Stack<Token> operators = new Stack<Token>();
             foreach (Token token in equation)
             {
                 if (token.tokenType == Token.TokenType.Operand)
                 {
-                    TEMP.Add(token);
+                    reversedEquation.Add(token);
                 }
                 if (token.tokenType == Token.TokenType.Operator)
                 {
                     if (token.value == "(")
                     {
-                        OPERATORS.Push(token);
+                        operators.Push(token);
                     }
                     else if (token.value == ")")
                     {
-                        while (OPERATORS.Peek().value != "(")
+                        while (operators.Peek().value != "(")
                         {
-                            TEMP.Add(OPERATORS.Pop());
+                            reversedEquation.Add(operators.Pop());
                         }
-                        OPERATORS.Pop();
+                        operators.Pop();
                     }
                     else
                     {
-                        while (OPERATORS.Count != 0 && OPERATORS.Peek().priority >= token.priority)
+                        while (operators.Count != 0 && operators.Peek().priority >= token.priority)
                         {
-                            TEMP.Add(OPERATORS.Pop());
+                            reversedEquation.Add(operators.Pop());
                         }
-                        OPERATORS.Push(token);
+                        operators.Push(token);
                     }
                 }
             }
-            while (OPERATORS.Count != 0)
+            while (operators.Count != 0)
             {
-                TEMP.Add(OPERATORS.Pop());
+                reversedEquation.Add(operators.Pop());
             }
-            this.equation = TEMP;
+
-            return equationToString();
+            return reversedEquation;
         }
 
         
-        public string Solve(List<Token> equation)
+        public static string Solve(List<Token> originalEquation)
         {
-            ToReverseNotation(equation);
+            List<Token> reversedEquation = ToReverseNotation(originalEquation);
             Stack<Token> stack = new Stack<Token>();
-            foreach (Token token in this.equation)
+            foreach (Token token in reversedEquation)
             {
                 double result, left, right;
                 if (token.tokenType == Token.TokenType.Operand)
@@ -97,16 +95,5 @@
             }
             return stack.Pop().value;
         }
-
-        
-        public string equationToString()
-        {
-            string equationString = "";
-            foreach (Token token in equation)
-            {
-                equationString += token.value + " ";
-            }
-            return equationString;
-        }
     }
 }