Home | History | Annotate | Download | only in axes 
      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: UnionChildIterator.java 468655 2006-10-28 07:12:06Z minchau $
     20  */
     21 package org.apache.xpath.axes;
     22 
     23 import org.apache.xml.dtm.DTMIterator;
     24 import org.apache.xpath.XPathContext;
     25 import org.apache.xpath.objects.XObject;
     26 import org.apache.xpath.patterns.NodeTest;
     27 
     28 /**
     29  * This class defines a simplified type of union iterator that only
     30  * tests along the child axes.  If the conditions are right, it is
     31  * much faster than using a UnionPathIterator.
     32  */
     33 public class UnionChildIterator extends ChildTestIterator
     34 {
     35     static final long serialVersionUID = 3500298482193003495L;
     36   /**
     37    * Even though these may hold full LocPathIterators, this array does
     38    * not have to be cloned, since only the node test and predicate
     39    * portion are used, and these only need static information.  However,
     40    * also note that index predicates can not be used!
     41    */
     42   private PredicatedNodeTest[] m_nodeTests = null;
     43 
     44   /**
     45    * Constructor for UnionChildIterator
     46    */
     47   public UnionChildIterator()
     48   {
     49     super(null);
     50   }
     51 
     52   /**
     53    * Add a node test to the union list.
     54    *
     55    * @param test reference to a NodeTest, which will be added
     56    * directly to the list of node tests (in other words, it will
     57    * not be cloned).  The parent of this test will be set to
     58    * this object.
     59    */
     60   public void addNodeTest(PredicatedNodeTest test)
     61   {
     62 
     63     // Increase array size by only 1 at a time.  Fix this
     64     // if it looks to be a problem.
     65     if (null == m_nodeTests)
     66     {
     67       m_nodeTests = new PredicatedNodeTest[1];
     68       m_nodeTests[0] = test;
     69     }
     70     else
     71     {
     72       PredicatedNodeTest[] tests = m_nodeTests;
     73       int len = m_nodeTests.length;
     74 
     75       m_nodeTests = new PredicatedNodeTest[len + 1];
     76 
     77       System.arraycopy(tests, 0, m_nodeTests, 0, len);
     78 
     79       m_nodeTests[len] = test;
     80     }
     81     test.exprSetParent(this);
     82   }
     83 
     84   /**
     85    * This function is used to fixup variables from QNames to stack frame
     86    * indexes at stylesheet build time.
     87    * @param vars List of QNames that correspond to variables.  This list
     88    * should be searched backwards for the first qualified name that
     89    * corresponds to the variable reference qname.  The position of the
     90    * QName in the vector from the start of the vector will be its position
     91    * in the stack frame (but variables above the globalsTop value will need
     92    * to be offset to the current stack frame).
     93    */
     94   public void fixupVariables(java.util.Vector vars, int globalsSize)
     95   {
     96     super.fixupVariables(vars, globalsSize);
     97     if (m_nodeTests != null) {
     98       for (int i = 0; i < m_nodeTests.length; i++) {
     99         m_nodeTests[i].fixupVariables(vars, globalsSize);
    100       }
    101     }
    102   }
    103 
    104   /**
    105    * Test whether a specified node is visible in the logical view of a
    106    * TreeWalker or NodeIterator. This function will be called by the
    107    * implementation of TreeWalker and NodeIterator; it is not intended to
    108    * be called directly from user code.
    109    * @param n  The node to check to see if it passes the filter or not.
    110    * @return  a constant to determine whether the node is accepted,
    111    *   rejected, or skipped, as defined  above .
    112    */
    113   public short acceptNode(int n)
    114   {
    115     XPathContext xctxt = getXPathContext();
    116     try
    117     {
    118       xctxt.pushCurrentNode(n);
    119       for (int i = 0; i < m_nodeTests.length; i++)
    120       {
    121         PredicatedNodeTest pnt = m_nodeTests[i];
    122         XObject score = pnt.execute(xctxt, n);
    123         if (score != NodeTest.SCORE_NONE)
    124         {
    125           // Note that we are assuming there are no positional predicates!
    126           if (pnt.getPredicateCount() > 0)
    127           {
    128             if (pnt.executePredicates(n, xctxt))
    129               return DTMIterator.FILTER_ACCEPT;
    130           }
    131           else
    132             return DTMIterator.FILTER_ACCEPT;
    133 
    134         }
    135       }
    136     }
    137     catch (javax.xml.transform.TransformerException se)
    138     {
    139 
    140       // TODO: Fix this.
    141       throw new RuntimeException(se.getMessage());
    142     }
    143     finally
    144     {
    145       xctxt.popCurrentNode();
    146     }
    147     return DTMIterator.FILTER_SKIP;
    148   }
    149 
    150 }
    151