/* transformer.java -- Content model transforms.   Copyright (C) 2005 Free Software Foundation, Inc.This file is part of GNU Classpath.GNU Classpath is free software; you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe Free Software Foundation; either version 2, or (at your option)any later version.GNU Classpath is distributed in the hope that it will be useful, butWITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNUGeneral Public License for more details.You should have received a copy of the GNU General Public Licensealong with GNU Classpath; see the file COPYING.  If not, write to theFree Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA02110-1301 USA.Linking this library statically or dynamically with other modules ismaking a combined work based on this library.  Thus, the terms andconditions of the GNU General Public License cover the wholecombination.As a special exception, the copyright holders of this library give youpermission to link this library with independent modules to produce anexecutable, regardless of the license terms of these independentmodules, and to copy and distribute the resulting executable underterms of your choice, provided that you also meet, for each linkedindependent module, the terms and conditions of the license of thatmodule.  An independent module is a module which is not derived fromor based on this library.  If you modify this library, you may extendthis exception to your version of the library, but you are notobligated to do so.  If you do not wish to do so, delete thisexception statement from your version. */package gnu.javax.swing.text.html.parser.models;import java.io.Serializable;import javax.swing.text.html.parser.ContentModel;import javax.swing.text.html.parser.DTD;/** * Transforms the standard ContentModel tree into the internal representation, * used in this implementation. * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org) */public class transformer  implements Serializable{  private static final long serialVersionUID = 1;  /**   * All binary operators.   */  protected static String binary = "&|,";  /**   * All unary operators.   */  protected static String unary = "+*?";  /**   * Measure length of the linked list of the content models.   * @param c The heading element of the linked list.   * @return the length of the list (0 for null 1 if c!=null and c.next==null,   * etc.   */  public static int measureChainLength(ContentModel c)  {    if (c == null)      return 0;    else      return measureChainLength(c.next) + 1;  }  /**   * Transform into internal representation without usind dtd.   * This should be used only for testing.   */  public static node transform(ContentModel c)  {    return transform(c, null);  }  /**   * Transform into internal representation.   * @param c a model to transform   * @return a transformed model   * @throws Error if the model structure contains errors.   */  public static node transform(ContentModel c, DTD dtd)  {    // Handle the special cases first.    if (c.content instanceof node)      return (node) c.content;    // Do the typical transform.    node n;    /* Case with the single token */    if (c.next == null)      {        n = optionalTransform(c, dtd);      }    else /* Case with the chain of the multiple tokens. */      {        node[] l = new node[ measureChainLength(c) ];        ContentModel m = c;        for (int i = 0; i < l.length; i++)          {            if (m.content instanceof ContentModel)              {                ContentModel nested = (ContentModel) m.content;                if (nested.next == null &&                    !(nested.content instanceof ContentModel)                   )                  {                    l [ i ] =                      new node((char) m.type, (char) nested.type, nested.content);                  }                else                  {                    l [ i ] = transform(nested, dtd);                  }              }            else              l [ i ] = new node((char) 0, (char) 0, m.content);            addtype(l [ i ], (char) m.type);            m = m.next;          }        if (isBinary(c.type))          for (int i = 0; i < l.length; i++)            {              l [ i ].binary = (char) c.type;            }        n = new list(l);      }    addtype(n, (char) c.type);    return n;  }  /**   * True for binary operator   * @param c a character to test   * @return true for [ ,&| ], false otherwise.   */  private static boolean isBinary(int c)  {    return binary.indexOf((char) c) >= 0;  }  /**   * True for unary operator.   * @param c a character to test   * @return true for [ +?* ], false otherwise.   */  private static boolean isUnary(int c)  {    return unary.indexOf((char) c) >= 0;  }  /**   * Assign an operation type for the given node.   * @param n A node to set the operation to.   * @param type Either binary or unary operation, is assigned to the   * corresponding field of the node.   * @throws error if the operation type is not   * representing a valid unary or binary operation.   */  private static void addtype(node n, char type)  {    if (isBinary(type))      n.binary = type;    else if (isUnary(type))      n.unary = type;    else if (type != 0)      throw new Error("Invalid operation '" + (char) type + "'");  }  private static node optionalTransform(ContentModel c, DTD dtd)  {    node n;    if (c.content instanceof ContentModel)      n = transform((ContentModel) c.content, dtd);    else      /* A single token with the specified operation */      n = new node((char) 0, (char) 0, c.content);    return n;  }}