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1
5 package org.h2.index;
6
7 import java.sql.SQLException  ;
8
9 import org.h2.engine.Constants;
10 import org.h2.message.Message;
11 import org.h2.result.Row;
12 import org.h2.result.SearchRow;
13
14
17 public class BtreeCursor implements Cursor {
18 private BtreeIndex index;
19 private BtreePosition top;
20 private Row current;
21 private boolean first;
22 private SearchRow last;
23
24 BtreeCursor(BtreeIndex index, SearchRow last) {
25 this.index = index;
26 this.last = last;
27 first = true;
28 }
29
30 void setStackPosition(int position) {
31 top.position = position;
32 }
33
34 void push(BtreePage page, int position) {
35 if (Constants.CHECK && (top != null && top.page == page)) {
36 throw Message.getInternalError();
37 }
38 top = new BtreePosition(page, position, top);
39 }
40
41 BtreePosition pop() {
42 BtreePosition t = top;
43 if (t == null) {
44 return null;
45 }
46 top = top.next;
47 return t;
48 }
49
50 void setCurrentRow(int pos) throws SQLException {
51 current = pos == POS_NO_ROW ? null : index.getRow(pos);
52 }
53
54 public Row get() throws SQLException {
55 return current;
56 }
57
58 public int getPos() {
59 return current.getPos();
60 }
61
62 public boolean next() throws SQLException {
63 if (first) {
64 first = false;
65 return current != null;
66 }
67 top.page.next(this, top.position);
68 if(current != null && last != null) {
69 if (index.compareRows(current, last) > 0) {
70 current = null;
71 }
72 }
73 return current != null;
74 }
75
76 }
77 |
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