FromNextSibling


1   /*
2    * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3    *
4    * This file is part of Resin(R) Open Source
5    *
6    * Each copy or derived work must preserve the copyright notice and this
7    * notice unmodified.
8    *
9    * Resin Open Source is free software; you can redistribute it and/or modify
10   * it under the terms of the GNU General Public License as published by
11   * the Free Software Foundation; either version 2 of the License, or
12   * (at your option) any later version.
13   *
14   * Resin Open Source is distributed in the hope that it will be useful,
15   * but WITHOUT ANY WARRANTY; without even the implied warranty of
16   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17   * of NON-INFRINGEMENT.  See the GNU General Public License for more
18   * details.
19   *
20   * You should have received a copy of the GNU General Public License
21   * along with Resin Open Source; if not, write to the
22   *   Free SoftwareFoundation, Inc.
23   *   59 Temple Place, Suite 330
24   *   Boston, MA 02111-1307  USA
25   *
26   * @author Scott Ferguson
27   */
28  
29  package com.caucho.xpath.pattern;
30  
31  import com.caucho.xpath.Env;
32  import com.caucho.xpath.ExprEnvironment;
33  import com.caucho.xpath.XPathException;
34  
35  import org.w3c.dom.Node  ;
36  
37  /**
38   * matches following siblings
39   */
40  public class FromNextSibling extends Axis {
41    public FromNextSibling(AbstractPattern parent)
42    {
43      super(parent);
44  
45      if (parent == null)
46        throw new RuntimeException  ();
47    }
48  
49    /**
50     * matches if we can find a previous sibling that matches the parent.
51     *
52     * @param node the current node
53     * @param env the variable environment
54     *
55     * @return true if the pattern matches
56     */
57    public boolean match(Node   node, ExprEnvironment env)
58      throws XPathException
59    {
60      if (node == null)
61        return false;
62  
63      for (node = node.getPreviousSibling();
64       node != null;
65       node = node.getPreviousSibling()) {
66        if (_parent.match(node, env))
67      return true;
68      }
69  
70      return false;
71    }
72  
73    /**
74     * The count of nodes between the test-node and the axis.
75     *
76     * @param node the current node
77     * @param env the variable environment
78     */
79    public int position(Node   node, Env env, AbstractPattern pattern)
80      throws XPathException
81    {
82      int index = env.getPositionIndex();
83  
84      int count = 1;
85      while ((node = node.getPreviousSibling()) != null) {
86        if (_parent.match(node, env)) {
87          if (--index <= 0) {
88            // Test if there are more possible roots.
89            for (node = node.getPreviousSibling();
90                 node != null;
91                 node = node.getPreviousSibling()) {
92              if (_parent.match(node, env)) {
93                env.setMorePositions(true);
94                break;
95              }
96            }
97            return count;
98          }
99        }
100 
101       if (pattern.match(node, env))
102     count++;
103     }
104 
105     return count;
106   }
107 
108   /**
109    * Returns true if the pattern is strictly ascending.
110    */
111   public boolean isStrictlyAscending()
112   {
113     if (_parent == null)
114       return true;
115     else
116       return _parent.isSingleSelect();
117   }
118 
119   /**
120    * Returns the first node in the selection order.
121    *
122    * @param node the current node
123    *
124    * @return the first node
125    */
126   public Node   firstNode(Node   node, ExprEnvironment env)
127   {
128     return node.getNextSibling();
129   }
130 
131   /**
132    * Returns the next node in the selection order.
133    *
134    * @param node the current node
135    * @param lastNode the last node
136    *
137    * @return the next node
138    */
139   public Node   nextNode(Node   node, Node   lastNode)
140   {
141     return node.getNextSibling();
142   }
143 
144   public String   toString()
145   {
146     return getPrefix() + "following-sibling::";
147   }
148 }
149
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