Program.cs

namespace ExpressionParser
{
 internal class Program
 {
 static void Main(string[] args)
 {
 Console.WriteLine(""" 
 Sample implementation of operator-precedence expression parser. The following lexemes and operations are supported:

 - Numbers One or more '0'-'9' characters.Limited to 32 bit integer values.
 - Variables One or more 'a'-'z' and '_' characters.
 - Grouping ((x + y) * z)
 - Prefix operations -x, --x, ++x
 - Postfix operations x++, x--
 - Multiplicative x * y, x / y
 - Additive x + y, x - y
 - Relational x > y, x < y, x >= y, x <= y
 - Equality x == y, x != y
 - Conditional Ternary ?: operator. Expression that evaluates to a positive integer will be considered a true condition.
 - Assignment x = y, x += y, x -= y, x *= y, x /= y

 """);

 Console.WriteLine("Please, enter the expression:");
 string? expression = Console.ReadLine();
 var variables = new Dictionary<string, int>();

 while (!string.IsNullOrEmpty(expression))
 {
 Process(expression, variables);
 expression = Console.ReadLine();
 }
 }

 static void Process(string expression, Dictionary<string, int> variables)
 {
 try
 {
 var reducer = new ExpressionEvaluator(variables);
 var parser = new Parser(reducer);
 parser.Parse(expression);
 Console.WriteLine($"Result: {reducer.GetResult()}");
 }
 catch (Exception ex)
 {
 Console.WriteLine("Failed to evaluated with the following error: " + ex.Message);
 }
 }
 }
}