// File: PostfixEvaluatorTest.java

// Evaluates arithmetic expressions in postfix notation, read from
// a data file.

// The file consists of pairs of lines.  The first line of each pair
// is an infix expression, and the second is the equivalent postfix
// expression. Assumes valid input.

import java.io.File;
import java.io.IOException;
import java.util.Scanner;

/**
 * Test class for the PostfixEvaluator class
 */
public class PostfixEvaluatorTest
{
   public static void main(String[] args) throws IOException
   {
      PostfixEvaluator p = new PostfixEvaluator();

      Scanner inFile = new Scanner(new File("postfix.txt"));

      while (inFile.hasNext()) // while not eof...
      {
         // read first line of each pair - the infix expression
         String infix = inFile.nextLine();
         System.out.println("   Infix expression:  \t" + infix);

         // read second line of each pair - the postfix expression
         String postfix = inFile.nextLine();
         System.out.println("   Postfix expression:\t" + postfix);

         double result = p.evaluate(postfix);
         System.out.println("   Result = " + result + "\n");
      }
      // loop postcondition: at eof
      inFile.close();

   }
}

/* sample output:

Infix expression:    3 + 4 * 5
Postfix expression:  3 4 5 * +
Result = 23.0

Infix expression:    (3 + 4) * 5
Postfix expression:  3 4 + 5 *
Result = 35.0

Infix expression:    ((3 - (4 + 5)) * 6) $ (1 + 2)
Postfix expression:  3 4 5 + - 6 * 1 2 + $
Result = -46656.0

Infix expression:    (3 + 4) * (5 - 6) $ 1 * 2
Postfix expression:  3 4 + 5 6 - 1 $ * 2 *
Result = -14.0

Infix expression:    (3 + 4) * (5 $ (6 - 1) + 2) - 7
Postfix expression:  5 6 1 - $ 2 + 3 4 + * 7 -
Result = 21882.0

*/