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: FuncPosition.java 468655 2006-10-28 07:12:06Z minchau $
20 */
21package org.apache.xpath.functions;
22
23import org.apache.xml.dtm.DTM;
24import org.apache.xml.dtm.DTMIterator;
25import org.apache.xpath.XPathContext;
26import org.apache.xpath.axes.SubContextList;
27import org.apache.xpath.compiler.Compiler;
28import org.apache.xpath.objects.XNumber;
29import org.apache.xpath.objects.XObject;
30
31/**
32 * Execute the Position() function.
33 * @xsl.usage advanced
34 */
35public class FuncPosition extends Function
36{
37    static final long serialVersionUID = -9092846348197271582L;
38  private boolean m_isTopLevel;
39
40  /**
41   * Figure out if we're executing a toplevel expression.
42   * If so, we can't be inside of a predicate.
43   */
44  public void postCompileStep(Compiler compiler)
45  {
46    m_isTopLevel = compiler.getLocationPathDepth() == -1;
47  }
48
49  /**
50   * Get the position in the current context node list.
51   *
52   * @param xctxt Runtime XPath context.
53   *
54   * @return The current position of the itteration in the context node list,
55   *         or -1 if there is no active context node list.
56   */
57  public int getPositionInContextNodeList(XPathContext xctxt)
58  {
59
60    // System.out.println("FuncPosition- entry");
61    // If we're in a predicate, then this will return non-null.
62    SubContextList iter = m_isTopLevel ? null : xctxt.getSubContextList();
63
64    if (null != iter)
65    {
66      int prox = iter.getProximityPosition(xctxt);
67
68      // System.out.println("FuncPosition- prox: "+prox);
69      return prox;
70    }
71
72    DTMIterator cnl = xctxt.getContextNodeList();
73
74    if (null != cnl)
75    {
76      int n = cnl.getCurrentNode();
77      if(n == DTM.NULL)
78      {
79        if(cnl.getCurrentPos() == 0)
80          return 0;
81
82        // Then I think we're in a sort.  See sort21.xsl. So the iterator has
83        // already been spent, and is not on the node we're processing.
84        // It's highly possible that this is an issue for other context-list
85        // functions.  Shouldn't be a problem for last(), and it shouldn't be
86        // a problem for current().
87        try
88        {
89          cnl = cnl.cloneWithReset();
90        }
91        catch(CloneNotSupportedException cnse)
92        {
93          throw new org.apache.xml.utils.WrappedRuntimeException(cnse);
94        }
95        int currentNode = xctxt.getContextNode();
96        // System.out.println("currentNode: "+currentNode);
97        while(DTM.NULL != (n = cnl.nextNode()))
98        {
99          if(n == currentNode)
100            break;
101        }
102      }
103      // System.out.println("n: "+n);
104      // System.out.println("FuncPosition- cnl.getCurrentPos(): "+cnl.getCurrentPos());
105      return cnl.getCurrentPos();
106    }
107
108    // System.out.println("FuncPosition - out of guesses: -1");
109    return -1;
110  }
111
112  /**
113   * Execute the function.  The function must return
114   * a valid object.
115   * @param xctxt The current execution context.
116   * @return A valid XObject.
117   *
118   * @throws javax.xml.transform.TransformerException
119   */
120  public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
121  {
122    double pos = (double) getPositionInContextNodeList(xctxt);
123
124    return new XNumber(pos);
125  }
126
127  /**
128   * No arguments to process, so this does nothing.
129   */
130  public void fixupVariables(java.util.Vector vars, int globalsSize)
131  {
132    // no-op
133  }
134}
135