Question

Given a dynamic if statement in a String is there a method in .net to evaluate and return the correct result.

I.E.

    static void Main(string[] args)
    {
        String a = "if(\"Alex\" == \"Alex\"){return 1;}else{return 0;}";
        passThroughTest.Program.evalStatement(a);
    }
    public static void evalStatement(String statement)
    {

        //Evaluation of Statement

     }

This isn’t perfect but in this case the end result would be a 1. This seems ‘stupid’ from this point of view, but its for a more complex engine which needs to draw on similar syntax to evaluate.

Am I at a point where I need to write a parser of some sort and evaluate the statements…?

Thanks for your help!

Answer 1

• You can use javascript.net

  Sample code from their website:

  // Initialize a context
  using (JavascriptContext context = new JavascriptContext()) {
  
      // Setting external parameters for the context
      context.SetParameter("console", new SystemConsole());
      context.SetParameter("message", "Hello World !");
      context.SetParameter("number", 1);
  
      // Script
      string script = @"
          var i;
          for (i = 0; i < 5; i++)
              console.Print(message + ' (' + i + ')');
          number += i;
      ";
  
      // Running the script
      context.Run(script);
  
      // Getting a parameter
      Console.WriteLine("number: " + context.GetParameter("number"));
  }
  

• Or use C# expression tree, see Building Expression Evaluator with Expression Trees