code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the  "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * $Id$
   */
  
  package org.apache.xalan.xsltc.dom;
  
  import org.apache.xalan.xsltc.runtime.BasisLibrary;
  import org.apache.xml.dtm.DTMAxisIterator;
  import org.apache.xml.dtm.ref.DTMAxisIteratorBase;
  
  /**
   * A step iterator is used to evaluate expressions like "BOOK/TITLE". 
   * A better name for this iterator would have been ParentIterator since 
   * both "BOOK" and "TITLE" are steps in XPath lingo. Step iterators are 
   * constructed from two other iterators which we are going to refer to 
   * as "outer" and "inner". Every node from the outer iterator (the one 
   * for BOOK in our example) is used to initialize the inner iterator. 
   * After this initialization, every node from the inner iterator is 
   * returned (in essence, implementing a "nested loop").
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   * @author Erwin Bolwidt <ejb@klomp.org>
   * @author Morten Jorgensen
   */
  public class StepIterator extends DTMAxisIteratorBase {
  
      /**
       * A reference to the "outer" iterator.
       */
      protected DTMAxisIterator _source;
  
      /**
       * A reference to the "inner" iterator.
       */
      protected DTMAxisIterator _iterator;
  
      /**
       * Temp variable to store a marked position.
       */
      private int _pos = -1;
  
      public StepIterator(DTMAxisIterator source, DTMAxisIterator iterator) {
  	_source = source;
  	_iterator = iterator;
  // System.out.println("SI source = " + source + " this = " + this);
  // System.out.println("SI iterator = " + iterator + " this = " + this);
      }
  
  
      public void setRestartable(boolean isRestartable) {
  	_isRestartable = isRestartable;
  	_source.setRestartable(isRestartable);
  	_iterator.setRestartable(true); 	// must be restartable
      }
  
      public DTMAxisIterator cloneIterator() {
  	_isRestartable = false;
  	try {
  	    final StepIterator clone = (StepIterator) super.clone();
  	    clone._source = _source.cloneIterator();
  	    clone._iterator = _iterator.cloneIterator();
  	    clone._iterator.setRestartable(true); 	// must be restartable
  	    clone._isRestartable = false;
  	    return clone.reset();
  	}
  	catch (CloneNotSupportedException e) {
  	    BasisLibrary.runTimeError(BasisLibrary.ITERATOR_CLONE_ERR,
  				      e.toString());
  	    return null;
  	}
      }
      
      public DTMAxisIterator setStartNode(int node) {
  	if (_isRestartable) {
  	    // Set start node for left-hand iterator...
  	    _source.setStartNode(_startNode = node);
  
  	    // ... and get start node for right-hand iterator from left-hand,
  	    // with special case for //* path - see ParentLocationPath
  	    _iterator.setStartNode(_includeSelf ? _startNode : _source.next());
  	    return resetPosition();
  	}
  	return this;
      }
  
      public DTMAxisIterator reset() {
  	_source.reset();
  	// Special case for //* path - see ParentLocationPath
  	_iterator.setStartNode(_includeSelf ? _startNode : _source.next());
  	return resetPosition();
      }
      
      public int next() {
  	for (int node;;) {
  	    // Try to get another node from the right-hand iterator
  	    if ((node = _iterator.next()) != END) {
  		return returnNode(node);
  	    }
  	    // If not, get the next starting point from left-hand iterator...
  	    else if ((node = _source.next()) == END) {
  		return END;
  	    }
  	    // ...and pass it on to the right-hand iterator
  	    else {
  		_iterator.setStartNode(node);
  	    }
  	}
      }
  
      public void setMark() {
  	_source.setMark();
  	_iterator.setMark();
  	//_pos = _position;
      }
  
      public void gotoMark() {
  	_source.gotoMark();
  	_iterator.gotoMark();
  	//_position = _pos;
      }
  }
  