// **** Imports ****
import java.io.*;
import java.util.*;

/** 
 * Class: TrivialExample1.
 * <br>Description: This trivial example illustrates how to use
 *  the  buildFromInfix and evaluate methods in the ExprEvaluator
 * class.
 *<p>
 * To evaluate prefix or postfix expressions, simply replace "buildFromInfix" by
 * "buildFromPrefix" or "buildFromPostfix".
 * <p>
 * <b>Requires:</b>
 * <br>ExprEvaluator.java
 * <br>EasyFormat.java
 * <br>DoubleScanner.java
 * @version Date: 6/10/2008
 * @author James Brink, brinkje@plu.edu
 */
public class TrivialExample1 {

   double xVal;
   double yVal;
   double infixVal;
   String infix;
   ExprEvaluator evaluator = new ExprEvaluator();
   Scanner scan = new Scanner(System.in);

   /**
    * Constructor for TrivialExample1.
    *
    * Note:  in this case, the expression only uses x and y.  Hence the t
    * parameter is just set to 0 when evaluating the expression.
    */
   public TrivialExample1() {
      // get input
      System.out.print("Enter the first value for x: ");
      xVal = scan.nextDouble();
      System.out.print("Enter the first value for y: ");
      yVal = scan.nextDouble();
      scan.nextLine();   //  read rest of line
      System.out.print("Enter the expression to be evaluated: ");
      infix = scan.nextLine();

      // evaluate expression at several points and print the results
      try {
         evaluator.buildFromInfix(infix);
         System.out.println("The result are");
         for (int i = 0; i < 10; i++) {
            infixVal = evaluator.evaluate(0, xVal, yVal);
            System.out.println("x =" + xVal + ", y = " + yVal
                                   + ", expression = " + infixVal);
            xVal++;
            yVal++;
         }
      }catch (Exception e) {
         System.out.println ("Error:  namely: " + e);
      }
   }  // constructor TrivialExample1

   /**
    * Trivial main program that starts the application.
    */
   public static void main (String args[]) {
      TrivialExample1 app = new TrivialExample1();
      System.exit(0);
   }  // end main

} // class TrivialExample1