|
1
21 package com.db4o.inside.btree;
22
23 import com.db4o.*;
24 import com.db4o.foundation.*;
25
26
29 public class BTreePointer{
30
31 public static BTreePointer max(BTreePointer x, BTreePointer y) {
32 if (x == null) {
33 return x;
34 }
35 if (y == null) {
36 return y;
37 }
38 if (x.compareTo(y) > 0) {
39 return x;
40 }
41 return y;
42 }
43
44 public static BTreePointer min(BTreePointer x, BTreePointer y) {
45 if (x == null) {
46 return y;
47 }
48 if (y == null) {
49 return x;
50 }
51 if (x.compareTo(y) < 0) {
52 return x;
53 }
54 return y;
55 }
56
57 private final BTreeNode _node;
58
59 private final int _index;
60
61 private final Transaction _transaction;
62
63 private final YapReader _nodeReader;
64
65 public BTreePointer(Transaction transaction, YapReader nodeReader, BTreeNode node, int index) {
66 if(transaction == null || node == null){
67 throw new ArgumentNullException();
68 }
69 _transaction = transaction;
70 _nodeReader = nodeReader;
71 _node = node;
72 _index = index;
73 }
74
75 public final Transaction transaction() {
76 return _transaction;
77 }
78
79 public final int index(){
80 return _index;
81 }
82
83 public final BTreeNode node() {
84 return _node;
85 }
86
87 public final Object  key() {
88 return node().key(transaction(), nodeReader(), index());
89 }
90
91 public final Object value() {
92 return node().value(nodeReader(), index());
93 }
94
95 private YapReader nodeReader() {
96 return _nodeReader;
97 }
98
99 public BTreePointer next(){
100 int indexInMyNode = index() + 1;
101 while(indexInMyNode < node().count()){
102 if(node().indexIsValid(transaction(), indexInMyNode)){
103 return new BTreePointer(transaction(), nodeReader(), node(), indexInMyNode);
104 }
105 indexInMyNode ++;
106 }
107 int newIndex = -1;
108 BTreeNode nextNode = node();
109 YapReader nextReader = null;
110 while(newIndex == -1){
111 nextNode = nextNode.nextNode();
112 if(nextNode == null){
113 return null;
114 }
115 nextReader = nextNode.prepareRead(transaction());
116 newIndex = nextNode.firstKeyIndex(transaction());
117 }
118 return new BTreePointer(transaction(), nextReader, nextNode, newIndex);
119 }
120
121 public BTreePointer previous() {
122 int indexInMyNode = index() - 1;
123 while(indexInMyNode >= 0){
124 if(node().indexIsValid(transaction(), indexInMyNode)){
125 return new BTreePointer(transaction(), nodeReader(), node(), indexInMyNode);
126 }
127 indexInMyNode --;
128 }
129 int newIndex = -1;
130 BTreeNode previousNode = node();
131 YapReader previousReader = null;
132 while(newIndex == -1){
133 previousNode = previousNode.previousNode();
134 if(previousNode == null){
135 return null;
136 }
137 previousReader = previousNode.prepareRead(transaction());
138 newIndex = previousNode.lastKeyIndex(transaction());
139 }
140 return new BTreePointer(transaction(), previousReader, previousNode, newIndex);
141 }
142
143
144 public boolean equals(Object obj) {
145 if(this == obj){
146 return true;
147 }
148 if(! (obj instanceof BTreePointer)){
149 return false;
150 }
151 BTreePointer other = (BTreePointer) obj;
152
153 if(index() != other.index()){
154 return false;
155 }
156
157 return node().equals(other.node());
158 }
159
160 public String toString() {
161 return "BTreePointer(index=" + index() + ", node=" + node() + ")";
162 }
163
164 public int compareTo(BTreePointer y) {
165 if (null == y) {
166 throw new ArgumentNullException();
167 }
168 if (btree() != y.btree()) {
169 throw new IllegalArgumentException ();
170 }
171 return btree().compareKeys(key(), y.key());
172 }
173
174 private BTree btree() {
175 return node().btree();
176 }
177
178 public static boolean lessThan(BTreePointer x, BTreePointer y) {
179 return BTreePointer.min(x, y) == x
180 && !equals(x, y);
181 }
182
183 public static boolean equals(BTreePointer x, BTreePointer y) {
184 if (x == null) {
185 return y == null;
186 }
187 return x.equals(y);
188 }
189
190 public boolean isValid() {
191 return node().indexIsValid(transaction(), index());
192 }
193 }
194 |
Popular Tags |
Java API By Example, From Geeks To Geeks.