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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
7    *   "License"); you may not use this file except in compliance
8    *   with the License.  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,
13   *   software distributed under the License is distributed on an
14   *   "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *   KIND, either express or implied.  See the License for the
16   *   specific language governing permissions and limitations
17   *   under the License.
18   *
19   */
20  
21  package org.apache.directory.mavibot.btree.memory;
22  
23  
24  import java.io.IOException;
25  
26  
27  /**
28   * A class containing utility methods to be used internally. 
29   *
30   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
31   */
32  @SuppressWarnings("all")
33  /* No qualifier */class InternalUtil
34  {
35  
36      /**
37       * Sets the multi-value container(a.k.a dupsContainer) of the key at the given position.
38       * 
39       * This method will not update the existing value of 'dupsPos'. To change this value
40       * use {@link #changeNextDupsContainer(ParentPos, BTree)} or {@link #changePrevDupsContainer(ParentPos, BTree)}
41       *  
42       * @param parentPos the parent position object
43       * @param btree the BTree
44       */
45      public static void setDupsContainer( ParentPos parentPos, BTree btree )
46      {
47          if ( !btree.isAllowDuplicates() )
48          {
49              return;
50          }
51  
52          if ( parentPos.dupsContainer == null )
53          {
54              Leaf leaf = ( Leaf ) ( parentPos.page );
55              MultipleMemoryHolder mvHolder = ( MultipleMemoryHolder ) leaf.values[parentPos.pos];
56              if( !mvHolder.isSingleValue() )
57              {
58                  BTree dupsContainer = ( BTree ) mvHolder.getValue( btree );
59                  parentPos.dupsContainer = dupsContainer;
60              }
61          }
62      }
63  
64  
65      /**
66       * Sets the multi-value container(a.k.a dupsContainer) of the key at the given position
67       * and resets the 'dupsPos' to zero. This is mostly used by Cursor while navigating using
68       * next() 
69       *
70       * @param parentPos the parent position object
71       * @param btree the BTree
72       */
73      public static void changeNextDupsContainer( ParentPos parentPos, BTree btree ) throws IOException
74      {
75          if ( !btree.isAllowDuplicates() )
76          {
77              return;
78          }
79  
80          if ( parentPos.pos < parentPos.page.getNbElems() )
81          {
82              Leaf leaf = ( Leaf ) ( parentPos.page );
83              MultipleMemoryHolder mvHolder = ( MultipleMemoryHolder ) leaf.values[parentPos.pos];
84              if( !mvHolder.isSingleValue() )
85              {
86                  BTree dupsContainer = ( BTree ) mvHolder.getValue( btree );
87                  parentPos.dupsContainer = dupsContainer;
88                  parentPos.dupPos = 0;
89              }
90          }
91      }
92  
93  
94      /**
95       * Sets the multi-value container(a.k.a dupsContainer) of the key at the index below the given position( i.e pos - 1)
96       * and resets the 'dupsPos' to the number of elements present in the multi-value container.
97       * This is used by Cursor while navigating using prev() 
98       *
99       * @param parentPos the parent position object
100      * @param btree the BTree
101      */
102     public static void changePrevDupsContainer( ParentPos parentPos, BTree btree ) throws IOException
103     {
104         if ( !btree.isAllowDuplicates() )
105         {
106             return;
107         }
108 
109         int index = parentPos.pos - 1;
110         if ( index >= 0 )
111         {
112             Leaf leaf = ( Leaf ) ( parentPos.page );
113             MultipleMemoryHolder mvHolder = ( MultipleMemoryHolder ) leaf.values[index];
114             if( !mvHolder.isSingleValue() )
115             {
116                 BTree dupsContainer = ( BTree ) mvHolder.getValue( btree );
117                 parentPos.dupsContainer = dupsContainer;
118                 parentPos.dupPos = ( int ) parentPos.dupsContainer.getNbElems();
119             }
120             else
121             {
122                 parentPos.dupsContainer = null;
123                 parentPos.dupPos = -1;
124             }
125         }
126     }
127 
128 
129     /**
130      * Same as @see #changePrevDupsContainer(ParentPos, BTree) but with a different name
131      * to make it sound semantically right when used inside {@link BTreeFactory#getPathToRightMostLeaf(BTree)} 
132      */
133     public static void setLastDupsContainer( ParentPos parentPos, BTree btree ) throws IOException
134     {
135         changePrevDupsContainer( parentPos, btree );
136     }
137 }