code: ///////////////////////////////////////////////////////////////////////////////
  // For information as to what this class does, see the Javadoc, below.       //
  // Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,       //
  // 2007, 2008, 2009, 2010, 2014, 2015 by Peter Spirtes, Richard Scheines, Joseph   //
  // Ramsey, and Clark Glymour.                                                //
  //                                                                           //
  // This program is free software; you can redistribute it and/or modify      //
  // it under the terms of the GNU General Public License as published by      //
  // the Free Software Foundation; either version 2 of the License, or         //
  // (at your option) any later version.                                       //
  //                                                                           //
  // This program is distributed in the hope that it will be useful,           //
  // but WITHOUT ANY WARRANTY; without even the implied warranty of            //
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
  // GNU General Public License for more details.                              //
  //                                                                           //
  // You should have received a copy of the GNU General Public License         //
  // along with this program; if not, write to the Free Software               //
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA //
  ///////////////////////////////////////////////////////////////////////////////
  
  package edu.cmu.tetrad.calculator.expression;
  
  import java.util.List;
  
  /**
   * Sundry utility methods for expressions.
   */
  class ExpressionUtils {
  
      public static String renderExpression(Expression expression, ExpressionDescriptor.Position position, String token) {
  
          List<Expression> expressions = expression.getExpressions();
  
          if (position == ExpressionDescriptor.Position.INFIX
                  || (position == ExpressionDescriptor.Position.BOTH && expressions.size() == 2)) {
              Expression expression1 = expressions.get(0);
              Expression expression2 = expressions.get(1);
  
              ExpressionDescriptor.Position position1 = expression1.getPosition();
              ExpressionDescriptor.Position position2 = expression2.getPosition();
  
              StringBuilder buf = new StringBuilder();
  
              if (position1 == ExpressionDescriptor.Position.INFIX && !expression1.getToken().equals(token)) {
                  buf.append("(");
                  buf.append(expression1);
                  buf.append(")");
              } else {
                  buf.append(expression1);
              }
  
              buf.append(token);
  
              if (position2 == ExpressionDescriptor.Position.INFIX && !expression2.getToken().equals(token)) {
                  buf.append("(");
                  buf.append(expression2);
                  buf.append(")");
              } else {
                  buf.append(expression2);
              }
  
              return buf.toString();
  
  
  //            return "(" + expression1 + middleToken +
  //                    expression2 + ")";
          } else {
              StringBuilder buf = new StringBuilder();
              buf.append(token);
              buf.append("(");
  
              for (int i = 0; i < expressions.size(); i++) {
                  buf.append(expressions.get(i));
  
                  if (i < expressions.size() - 1) {
                      buf.append(", ");
                  }
              }
  
              buf.append(")");
              return buf.toString();
          }
      }
  
  }
  
  
  
  