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      1 /*
      2  * Licensed to the Apache Software Foundation (ASF) under one
      3  * or more contributor license agreements. See the NOTICE file
      4  * distributed with this work for additional information
      5  * regarding copyright ownership. The ASF licenses this file
      6  * to you under the Apache License, Version 2.0 (the  "License");
      7  * you may not use this file except in compliance with the License.
      8  * You may obtain a copy of the License at
      9  *
     10  *     http://www.apache.org/licenses/LICENSE-2.0
     11  *
     12  * Unless required by applicable law or agreed to in writing, software
     13  * distributed under the License is distributed on an "AS IS" BASIS,
     14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15  * See the License for the specific language governing permissions and
     16  * limitations under the License.
     17  */
     18 /*
     19  * $Id: ChildIterator.java 468655 2006-10-28 07:12:06Z minchau $
     20  */
     21 package org.apache.xpath.axes;
     22 
     23 import org.apache.xml.dtm.DTM;
     24 import org.apache.xml.dtm.DTMFilter;
     25 import org.apache.xpath.XPathContext;
     26 import org.apache.xpath.compiler.Compiler;
     27 
     28 /**
     29  * This class implements an optimized iterator for
     30  * "node()" patterns, that is, any children of the
     31  * context node.
     32  * @see org.apache.xpath.axes.LocPathIterator
     33  * @xsl.usage advanced
     34  */
     35 public class ChildIterator extends LocPathIterator
     36 {
     37     static final long serialVersionUID = -6935428015142993583L;
     38 
     39   /**
     40    * Create a ChildIterator object.
     41    *
     42    * @param compiler A reference to the Compiler that contains the op map.
     43    * @param opPos The position within the op map, which contains the
     44    * location path expression for this itterator.
     45    * @param analysis Analysis bits of the entire pattern.
     46    *
     47    * @throws javax.xml.transform.TransformerException
     48    */
     49   ChildIterator(Compiler compiler, int opPos, int analysis)
     50           throws javax.xml.transform.TransformerException
     51   {
     52     super(compiler, opPos, analysis, false);
     53 
     54     // This iterator matches all kinds of nodes
     55     initNodeTest(DTMFilter.SHOW_ALL);
     56   }
     57 
     58   /**
     59    * Return the first node out of the nodeset, if this expression is
     60    * a nodeset expression.  This is the default implementation for
     61    * nodesets.
     62    * <p>WARNING: Do not mutate this class from this function!</p>
     63    * @param xctxt The XPath runtime context.
     64    * @return the first node out of the nodeset, or DTM.NULL.
     65    */
     66   public int asNode(XPathContext xctxt)
     67     throws javax.xml.transform.TransformerException
     68   {
     69     int current = xctxt.getCurrentNode();
     70 
     71     DTM dtm = xctxt.getDTM(current);
     72 
     73     return dtm.getFirstChild(current);
     74   }
     75 
     76   /**
     77    *  Returns the next node in the set and advances the position of the
     78    * iterator in the set. After a NodeIterator is created, the first call
     79    * to nextNode() returns the first node in the set.
     80    *
     81    * @return  The next <code>Node</code> in the set being iterated over, or
     82    *   <code>null</code> if there are no more members in that set.
     83    */
     84   public int nextNode()
     85   {
     86   	if(m_foundLast)
     87   		return DTM.NULL;
     88 
     89     int next;
     90 
     91     m_lastFetched = next = (DTM.NULL == m_lastFetched)
     92                            ? m_cdtm.getFirstChild(m_context)
     93                            : m_cdtm.getNextSibling(m_lastFetched);
     94 
     95     // m_lastFetched = next;
     96     if (DTM.NULL != next)
     97     {
     98       m_pos++;
     99       return next;
    100     }
    101     else
    102     {
    103       m_foundLast = true;
    104 
    105       return DTM.NULL;
    106     }
    107   }
    108 
    109   /**
    110    * Returns the axis being iterated, if it is known.
    111    *
    112    * @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple
    113    * types.
    114    */
    115   public int getAxis()
    116   {
    117     return org.apache.xml.dtm.Axis.CHILD;
    118   }
    119 
    120 
    121 }
    122