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;
  
  /**
   * This is a special kind of iterator that takes a source iterator and a 
   * node N. If initialized with a node M (the parent of N) it computes the 
   * position of N amongst the children of M. This position can be obtained 
   * by calling getPosition().
   * It is an iterator even though next() will never be called. It is used to
   * match patterns with a single predicate like:
   *
   *    BOOK[position() = last()]
   *
   * In this example, the source iterator will return elements of type BOOK, 
   * a call to position() will return the position of N. Notice that because 
   * of the way the pattern matching is implemented, N will always be a node 
   * in the source since (i) it is a BOOK or the test sequence would not be 
   * considered and (ii) the source iterator is initialized with M which is 
   * the parent of N. Also, and still in this example, a call to last() will 
   * return the number of elements in the source (i.e. the number of BOOKs).
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   */
  public final class MatchingIterator extends DTMAxisIteratorBase {
  
      /**
       * A reference to a source iterator.
       */
      private DTMAxisIterator _source;
  
      /**
       * The node to match.
       */
      private final int _match;
  
      public MatchingIterator(int match, DTMAxisIterator source) {
  	_source = source;
  	_match = match;
      }
  
  
      public void setRestartable(boolean isRestartable) {
  	_isRestartable = isRestartable;
  	_source.setRestartable(isRestartable);
      }
  
      public DTMAxisIterator cloneIterator() {
  
  	try {
  	    final MatchingIterator clone = (MatchingIterator) super.clone();
  	    clone._source = _source.cloneIterator();
  	    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) {
  	    // iterator is not a clone
  	    _source.setStartNode(node);
  
  	    // Calculate the position of the node in the set
  	    _position = 1;
  	    while ((node = _source.next()) != END && node != _match) {
  		_position++;
  	    }
  	}
  	return this;
      }
  
      public DTMAxisIterator reset() {
  	_source.reset();
  	return resetPosition();
      }
      
      public int next() {
  	return _source.next();
      }
  	
      public int getLast() {
          if (_last == -1) {
              _last = _source.getLast();
          }
          return _last;
      }
  
      public int getPosition() {
  	return _position;
      }
  
      public void setMark() {
  	_source.setMark();
      }
  
      public void gotoMark() {
  	_source.gotoMark();
      }
  }
  