public void evaluate() {
   try {
     // clear problems and console messages
     problemsView.setText("");
     consoleView.setText("");
     // update status view
     statusView.setText(" Parsing ...");
     tabbedPane.setSelectedIndex(0);
     LispExpr root = Parser.parse(textView.getText());
     statusView.setText(" Running ...");
     tabbedPane.setSelectedIndex(1);
     // update run button
     runButton.setIcon(stopImage);
     runButton.setActionCommand("Stop");
     // start run thread
     runThread = new RunThread(root);
     runThread.start();
   } catch (SyntaxError e) {
     tabbedPane.setSelectedIndex(0);
     System.err.println(
         "Syntax Error at " + e.getLine() + ", " + e.getColumn() + " : " + e.getMessage());
   } catch (Error e) {
     // parsing error
     System.err.println(e.getMessage());
     statusView.setText(" Errors.");
   }
 }
 public void prettyPrint() {
   try {
     // clear old problem messages
     problemsView.setText("");
     // update status view
     statusView.setText(" Parsing ...");
     LispExpr root = Parser.parse(textView.getText());
     statusView.setText(" Pretty Printing ...");
     String newText = PrettyPrinter.prettyPrint(root);
     textView.setText(newText);
     statusView.setText(" Done.");
   } catch (Error e) {
     System.err.println(e.getMessage());
     statusView.setText(" Errors.");
   }
 }
 // bindKeyToCommand binds a given key sequence to a Lisp command
 // so that pressing the key sequence executes the command.
 public void bindKeyToCommand(String keySequence, String cmd) {
   bindKeyToCommand(keySequence, Parser.parse(cmd));
 }