content: /*
  * Conditions Of Use
  *
  * This software was developed by employees of the National Institute of
  * Standards and Technology (NIST), an agency of the Federal Government.
  * Pursuant to title 15 Untied States Code Section 105, works of NIST
  * employees are not subject to copyright protection in the United States
  * and are considered to be in the public domain.  As a result, a formal
  * license is not needed to use the software.
  *
  * This software is provided by NIST as a service and is expressly
  * provided "AS IS."  NIST MAKES NO WARRANTY OF ANY KIND, EXPRESS, IMPLIED
  * OR STATUTORY, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTY OF
  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT
  * AND DATA ACCURACY.  NIST does not warrant or make any representations
  * regarding the use of the software or the results thereof, including but
  * not limited to the correctness, accuracy, reliability or usefulness of
  * the software.
  *
  * Permission to use this software is contingent upon your acceptance
  * of the terms of this agreement
  *
  * .
  *
  */
  package gov2.nist.javax2.sip.message;
  
  import gov2.nist.javax2.sip.header.*;
  
  import java.util.ListIterator;
  import java.util.NoSuchElementException;
  
  /**
   * Iterator over lists of headers. Allows for uniform removal handling for singleton headers.
   * @author M. Ranganathan
   * @version 1.2 $Revision: 1.8 $ $Date: 2009/07/17 18:57:53 $
   * @since 1.1
   */
  public class HeaderIterator implements ListIterator {
      private boolean toRemove;
      private int index;
      private SIPMessage sipMessage;
      private SIPHeader sipHeader;
  
      protected HeaderIterator(SIPMessage sipMessage, SIPHeader sipHeader) {
          this.sipMessage = sipMessage;
          this.sipHeader = sipHeader;
      }
  
      public Object next() throws NoSuchElementException {
          if (sipHeader == null || index == 1)
              throw new NoSuchElementException();
          toRemove = true;
          index = 1;
          return (Object) sipHeader;
      }
  
      public Object previous() throws NoSuchElementException {
          if (sipHeader == null || index == 0)
              throw new NoSuchElementException();
          toRemove = true;
          index = 0;
          return (Object) sipHeader;
      }
  
      public int nextIndex() {
          return 1;
      }
  
      public int previousIndex() {
          return index == 0 ? -1 : 0;
      }
  
      public void set(Object header) {
          throw new UnsupportedOperationException();
      }
  
      public void add(Object header) {
          throw new UnsupportedOperationException();
      }
  
      public void remove() throws IllegalStateException {
          if (this.sipHeader == null)
              throw new IllegalStateException();
          if (toRemove) {
              this.sipHeader = null;
              this.sipMessage.removeHeader(sipHeader.getName());
          } else {
              throw new IllegalStateException();
          }
      }
  
      public boolean hasNext() {
          return index == 0;
      }
  
      public boolean hasPrevious() {
          return index == 1;
      }
  }
  