//Title:       Expression Test
//Version:     
//Copyright:   Copyright (c) 1998
//Author:      Dumb Crawford
//Company:     Programming Languages
//Description: 
package CSC350;

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import borland.jbcl.layout.*;
import borland.jbcl.control.*;

//import com.sun.java.swing.UIManager;
public class csc350 extends Applet {
  XYLayout xYLayout1 = new XYLayout();
  boolean isStandalone = false;
  TextControl ResulttextControl = new TextControl();
  ButtonControl buttonControl1 = new ButtonControl();
  TextFieldControl ExpressiontextFieldControl = new TextFieldControl();
//Get a parameter value
  
  public String getParameter(String key, String def) {
    return isStandalone ? System.getProperty(key, def) :
      (getParameter(key) != null ? getParameter(key) : def);
  }

  //Construct the applet
  
  public csc350() {
  }
//Initialize the applet
  
  public void init() {
    try {
    jbInit();
    }
    catch (Exception e) {
    e.printStackTrace();
    }
  }
  //static { 
  //  try { 
  //    //UIManager.setLookAndFeel(new com.sun.java.swing.plaf.metal.MetalLookAndFeel());
  //    //UIManager.setLookAndFeel(new com.sun.java.swing.plaf.motif.MotifLookAndFeel());
  //    UIManager.setLookAndFeel(new com.sun.java.swing.plaf.windows.WindowsLookAndFeel());
  //  }
  //  catch (Exception e) {}
  //}
//Component initialization
  
  private void jbInit() throws Exception {
    xYLayout1.setWidth(600);
    xYLayout1.setHeight(200);
    ResulttextControl.setText("Expression result");
    buttonControl1.setLabel("buttonControl1");
    buttonControl1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        buttonControl1_actionPerformed(e);
      }
    });
    ExpressiontextFieldControl.setText("346");
    this.setLayout(xYLayout1);
    this.add(ResulttextControl, new XYConstraints(15, 63, 352, -1));
    this.add(buttonControl1, new XYConstraints(40, 167, -1, -1));
    this.add(ExpressiontextFieldControl, new XYConstraints(20, 18, 340, -1));
  }
//Start the applet
  
  public void start() {
  }
//Stop the applet
  
  public void stop() {
  }
//Destroy the applet
  
  public void destroy() {
  }
//Get Applet information
  
  public String getAppletInfo() {
    return "Applet Information";
  }
//Get parameter info
  
  public String[][] getParameterInfo() {
    return null;
  }
//Main method
  
  public static void main(String[] args) {
    csc350 applet = new csc350();
    applet.isStandalone = true;
    DecoratedFrame frame = new DecoratedFrame();
    frame.setTitle("Applet Frame");
    frame.add(applet, BorderLayout.CENTER);
    applet.init();
    applet.start();
    frame.setSize(600,220);
    Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
    frame.setLocation((d.width - frame.getSize().width) / 2, (d.height - frame.getSize().height) / 2);
    frame.setVisible(true);
  }

   static String ParseString;
  static char CurrentChar='#';
  static int Index=0;
  static String ErrorMessage[] =
       {"Expected end of string",
        "Expecting )",
        "Expecting digit or ("};


  static void InitCurrent(String X)
    { ParseString = X;
      CurrentChar='#';
      Index=-1;
    }

  static void GetChar()
    { boolean NotDone = true;
      Index++;
      do
       if (Index < ParseString.length())
         if (ParseString.charAt(Index) == ' ')
           Index++;
         else
           NotDone = false;
       else
         NotDone = false;
      while (NotDone);

      if (Index >= ParseString.length())
        CurrentChar = '~';
      else
        CurrentChar = ParseString.charAt(Index);
    }

  static void ParseNumber(int Value[])
    {  int Z=0;
       while (CurrentChar >= '0' & CurrentChar <= '9')
         {
          Z=10*Z+(CurrentChar - '0');
          GetChar();
         }//end while
       Value[0] = Z; // return Z
    }

  static void Term(int Value[])
  // Term -> Number | ( Expression )
    { switch (CurrentChar) {
       case '0':
       case '1':
       case '2':
       case '3':
       case '4':
       case '5':
       case '6':
       case '7':
       case '8':
       case '9':
         ParseNumber(Value);
         break;
       case '(':
         GetChar();
         Expression(Value);
         if (CurrentChar==')')
           GetChar();
         else
           if (Value[1] < 0)
           { Value[1] = 1;
             //GetChar();
           }
         break;
       default:
         { if (Value[1] < 0)
             {Value[1] = 2;
              GetChar();}
         }
      }
    }


  static void Expression(int Value[])
   {  boolean isMinus = false;
      if (CurrentChar == '+')
        GetChar();
      else if (CurrentChar == '-')
        { isMinus = true;
          GetChar();
        }

      Term(Value);
      if (isMinus) Value[0] = -Value[0];

      int temp[]={0, -1};
      while (CurrentChar=='+'|CurrentChar=='-')
        { isMinus = (CurrentChar=='-');
          GetChar();
          Term(temp);
          if (Value[1] < 0) Value[1] = temp[1];
          if (isMinus)
            Value[0] -= temp[0];
          else
            Value[0] += temp[0];
        }
      }

  void buttonControl1_actionPerformed(ActionEvent e) {
    // do this
   String X;
   int J;
   X=ExpressiontextFieldControl.getText();
   InitCurrent(X);

   int Y[]={0,-1};
   GetChar();
   Expression(Y);
   if (CurrentChar != '~')
     if (Y[1] < 0) Y[1] = 0;
   if (Y[1] < 0)
     ResulttextControl.setText("The value of the expression is "
            +X.valueOf(Y[0]));
   else
     ResulttextControl.setText(ErrorMessage[Y[1]]);


  }
}