|
1 package com.daffodilwoods.daffodildb.server.datasystem.indexsystem;
2
3 import com.daffodilwoods.database.resource.DException;
4 import com.daffodilwoods.daffodildb.server.sql99.utils.*;
5 import com.daffodilwoods.daffodildb.server.sql99.expression.booleanvalueexpression.booleanvalueexpression;
6 import com.daffodilwoods.daffodildb.utils.parser.*;
7 import com.daffodilwoods.daffodildb.server.sql99.dql.queryexpression.*;
8 import com.daffodilwoods.daffodildb.server.datasystem.btree.BTree;
9 import com.daffodilwoods.daffodildb.server.datasystem.btree.BTreeElement;
10 import com.daffodilwoods.daffodildb.server.datasystem.btree.BTreeKey;
11
12
15
16 public class BTreeIterator {
17
18 BTree btree;
19 booleanvalueexpression condition;
20 _VariableValues variableValues;
21 BTreeKey currentKey;
22 _Reference[] references;
23
24 public BTreeIterator(BTree btree0,booleanvalueexpression condition0,_VariableValues variableValues0,_Reference[] references0) {
25 btree = btree0;
26 condition = condition0;
27 variableValues = variableValues0;
28 references = references0;
29 }
30
31 public boolean first() throws DException{
32 boolean flag = btree.first(currentKey);
33 while(flag) {
34 Object  vals = currentKey.getKey();
35 variableValues.setConditionVariableValue(references,vals instanceof Object [] ? (Object [])vals : new Object [] {vals},0);
36 if(condition.run(variableValues).hashCode() == 0){
37 move(currentKey);
38 return true;
39 }
40 flag = btree.next(currentKey);
41 }
42 return false;
43 }
44
45 public boolean next() throws DException{
46 boolean flag = btree.next(currentKey);
47 while(flag) {
48 Object vals = currentKey.getKey();
49 variableValues.setConditionVariableValue(references,vals instanceof Object [] ? (Object [])vals : new Object [] {vals},0);
50 if(condition.run(variableValues).hashCode() == 0){
51 move(currentKey);
52 return true;
53 }
54 flag = btree.next(currentKey);
55 }
56 return false;
57 }
58
59 public boolean last() throws DException{
60 boolean flag = btree.last(currentKey);
61 while(flag) {
62 Object vals = currentKey.getKey();
63 variableValues.setConditionVariableValue(references,vals instanceof Object [] ? (Object [])vals : new Object [] {vals},0);
64 if(condition.run(variableValues).hashCode() == 0){
65 move(currentKey);
66 return true;
67 }
68 flag = btree.previous(currentKey);
69 }
70 return false;
71 }
72
73 public boolean previous() throws DException{
74 boolean flag = btree.previous(currentKey);
75 while(flag) {
76 Object vals = currentKey.getKey();
77 variableValues.setConditionVariableValue(references,vals instanceof Object [] ? (Object [])vals : new Object [] {vals},0);
78 if(condition.run(variableValues).hashCode() == 0){
79 move(currentKey);
80 return true;
81 }
82 flag = btree.previous(currentKey);
83 }
84 return false;
85 }
86
87 public Object getKey() throws DException{
88 return currentKey;
89 }
90
91 public Object getObject() throws DException{
92 return currentKey == null ? null : currentKey.getValue();
93 }
94
95 public void move(Object key) throws DException{
96 currentKey = (BTreeKey)key;
97 }
98 }
99 |
Popular Tags |
Java API By Example, From Geeks To Geeks.