Node


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5    * modification, are permitted provided that the following conditions are met:
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8    * list of conditions and the following disclaimer.
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16   * software without specific prior written permission.
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39   * Redistribution and use in source and binary forms, with or without
40   * modification, are permitted provided that the following conditions are met:
41   *
42   * Redistributions of source code must retain the above copyright notice, this
43   * list of conditions and the following disclaimer.
44   *
45   * Redistributions in binary form must reproduce the above copyright notice,
46   * this list of conditions and the following disclaimer in the documentation
47   * and/or other materials provided with the distribution.
48   *
49   * Neither the name of the HSQL Development Group nor the names of its
50   * contributors may be used to endorse or promote products derived from this
51   * software without specific prior written permission.
52   *
53   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
54   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56   * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
57   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
58   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
59   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
60   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
61   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
62   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
63   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
64   */
65  
66  
67  package org.hsqldb;
68  
69  import java.io.IOException  ;
70  
71  import org.hsqldb.rowio.RowInputInterface;
72  import org.hsqldb.rowio.RowOutputInterface;
73  
74  // fredt@users 20020221 - patch 513005 by sqlbob@users (RMP)
75  // fredt@users 20020920 - path 1.7.1 - refactoring to cut mamory footprint
76  // fredt@users 20021205 - path 1.7.2 - enhancements
77  // fredt@users 20021215 - doc 1.7.2 - javadoc comments
78  
79  /**
80   *  The parent for all AVL node implementations, features factory methods for
81   *  its subclasses. Subclasses of Node vary in the way they hold
82   *  references to other Nodes in the AVL tree, or to their Row data.<br>
83   *
84   *  nNext links the Node objects belonging to different indexes for each
85   *  table row. It is used solely by Row to locate the node belonging to a
86   *  particular index.
87   *
88   *
89   * @author Thomas Mueller (Hypersonic SQL Group)
90   * @version 1.7.2
91   * @since Hypersonic SQL
92   */
93  abstract class Node {
94  
95      static final int NO_POS = CachedRow.NO_POS;
96      int              iBalance;    // currently, -2 means 'deleted'
97      Node             nNext;       // node of next index (nNext==null || nNext.iId=iId+1)
98  
99      static final Node newNode(Row r, int id, Table t) {
100 
101         switch (t.getIndexType()) {
102 
103             case Index.MEMORY_INDEX :
104                 return new MemoryNode(r);
105 
106             case Index.POINTER_INDEX :
107                 return new PointerNode((CachedRow) r, id);
108 
109             case Index.DISK_INDEX :
110             default :
111                 return new DiskNode((CachedRow) r, id);
112         }
113     }
114 
115     static final Node newNode(Row r, RowInputInterface in, int id,
116                               Table t) throws IOException  , HsqlException {
117 
118         switch (t.getIndexType()) {
119 
120             case Index.MEMORY_INDEX :
121                 return new MemoryNode(r);
122 
123             case Index.POINTER_INDEX :
124                 return new PointerNode((CachedRow) r, id);
125 
126             case Index.DISK_INDEX :
127             default :
128                 return new DiskNode((CachedRow) r, in, id);
129         }
130     }
131 
132     /**
133      *  This method unlinks the Node from the other Nodes in the same Index
134      *  and from the Row.
135      *
136      *  It must keep the links between the Nodes in different Indexes.
137      */
138     abstract void delete();
139 
140     /**
141      *  File offset of Node. Used with CachedRow objects only
142      */
143     abstract int getKey();
144 
145     /**
146      *  Return the Row Object that is linked to this Node.
147      */
148     abstract Row getRow() throws HsqlException;
149 
150     /**
151      *  Getters and setters for AVL index operations.
152      */
153     abstract boolean isLeft(Node node) throws HsqlException;
154 
155     abstract boolean isRight(Node node) throws HsqlException;
156 
157     abstract Node getLeft() throws HsqlException;
158 
159     abstract void setLeft(Node n) throws HsqlException;
160 
161     abstract Node getRight() throws HsqlException;
162 
163     abstract void setRight(Node n) throws HsqlException;
164 
165     abstract Node getParent() throws HsqlException;
166 
167     abstract void setParent(Node n) throws HsqlException;
168 
169     final int getBalance() throws HsqlException {
170 
171         if (Trace.DOASSERT) {
172             Trace.doAssert(iBalance != -2);
173         }
174 
175         return iBalance;
176     }
177 
178     abstract void setBalance(int b) throws HsqlException;
179 
180     abstract boolean isRoot();
181 
182     abstract boolean isFromLeft() throws HsqlException;
183 
184     /**
185      *  Returns the database table data for this Node
186      *
187      */
188     abstract Object  [] getData() throws HsqlException;
189 
190     abstract boolean equals(Node n);
191 
192     /**
193      *  Returns the Node Object that currently represents this Node in the
194      *  AVL index structure. In current implementations of Node this is
195      *  always the same as the this Object for MEMORY and TEXT tables but can
196      *  be a different Object for CACHED tables, where DiskNode Objects may
197      *  be freed from the Cache. Calling this method returns a Node with
198      *  currently valid pointers to its linked AVL Nodes.
199      *
200      */
201     Node getUpdatedNode() throws HsqlException {
202         return this;
203     }
204 
205     /**
206      *  Writes out the node in an implementation dependent way.
207      */
208     abstract void write(RowOutputInterface out) throws IOException  ;
209 
210     boolean isDeleted() {
211         return iBalance == -2;
212     }
213 }
214
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