/**
 * Copyright (c) 2001, Sergey A. Samokhodkin
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 * - Redistributions of source code must retain the above copyright notice, 
 * this list of conditions and the following disclaimer. 
 * - Redistributions in binary form 
 * must reproduce the above copyright notice, this list of conditions and the following 
 * disclaimer in the documentation and/or other materials provided with the distribution.
 * - Neither the name of jregex nor the names of its contributors may be used 
 * to endorse or promote products derived from this software without specific prior 
 * written permission. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY 
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
 * IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY 
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * @version 1.2_01
 */

package jregex.util.io;

import jregex.*;
import java.io.FilenameFilter;
import java.io.File;
import java.util.Enumeration;
import java.util.NoSuchElementException;

class PathElementEnumerator implements Enumeration{
   private PathElementEnumerator nextPEE;
   private PathElementMask mask;
   
   protected Enumeration entries;
   
   private Object nextObj;
   
   PathElementEnumerator(){}
   
   PathElementEnumerator(PathElementMask mask){
      this.mask=mask;
      PathElementMask nextMask=mask.next;
      if(nextMask!=null)nextPEE=nextMask.newEnumerator();
   }
   
   protected void setDir(File f){
	      entries=mask.elements(f);
   }
   
   public boolean hasMoreElements(){
      return (nextObj!=null || getNext());
   }
   
   public Object nextElement(){
      if(nextObj==null && !getNext()) throw new NoSuchElementException();
      Object tmp=nextObj;
      nextObj=null;
      return tmp;
   }
   
   private boolean getNext(){
      if(nextPEE==null){
         return (nextObj=nextPathEntry())!=null;
      }
      else{
         while(!nextPEE.hasMoreElements()){
            File f=nextPathEntry();
            if(f==null) return false;
            nextPEE.setDir(f);
         }
         nextObj=nextPEE.nextElement();
         return true;
      }
   }
   
   private File nextPathEntry(){
      if(entries==null || !entries.hasMoreElements()) return null;
      return (File)entries.nextElement();
   }
}