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1
33 package smallsql.database;
34
35
36 final class Join extends RowSource{
37
38 Expression condition; private int type;
40 RowSource left; RowSource right;
42 private boolean isBeforeFirst = true;
43 private boolean isAfterLast;
44 private boolean isOuterValid = true;
45
46 private boolean[] isFullNotValid;
48 private int fullRightRowCounter;
49 private int fullRowCount;
50 private int fullReturnCounter = -1;
51
52 private LongLongList rowPositions; private int row;
55
56 Join( int type, RowSource left, RowSource right, Expression condition ){
57 this.type = type;
58 this.condition = condition;
59 this.left = left;
60 this.right = right;
61 if(type == FULL_JOIN){
62 isFullNotValid = new boolean[10];
63 }
64 }
65
66
67 final boolean isScrollable(){
68 return false; }
70
71
72 void beforeFirst() throws Exception  {
73 left.beforeFirst();
74 right.beforeFirst();
75 isBeforeFirst = true;
76 isAfterLast = false;
77 fullRightRowCounter = 0;
78 fullRowCount = 0;
79 fullReturnCounter = -1;
80 row = 0;
81 }
82
83 boolean first() throws Exception {
84 boolean result = left.first() && right.first();
85 row = 1;
86 isBeforeFirst= false;
87 isAfterLast = false;
88 if(!result) noRow();
89 return result;
90 }
91
92
93 boolean next() throws Exception {
94 if(isAfterLast) return false;
95 boolean result;
96 row++;
97 if(fullReturnCounter >=0){
98 do{
99 if(fullReturnCounter >= fullRowCount){
100 noRow();
101 return false;
102 }
103 right.next();
104 }while(isFullNotValid[fullReturnCounter++]);
105 return true;
106 }
107 do{
108 if(isBeforeFirst){
109 result = left.next();
110 if(result){
111 result = right.first();
112 if(!result){
113 switch(type){
114 case LEFT_JOIN:
115 case FULL_JOIN:
116 isOuterValid = false;
117 isBeforeFirst = false;
118 right.nullRow();
119 return true;
120 }
121 }else fullRightRowCounter++;
122 }else{
123 if(type == FULL_JOIN){
125 while(right.next()){
126 fullRightRowCounter++;
127 }
128 fullRowCount = fullRightRowCounter;
129 }
130 }
131 }else{
132 result = right.next();
133 if(!result){
134 switch(type){
135 case LEFT_JOIN:
136 case FULL_JOIN:
137 if(isOuterValid){
138 isOuterValid = false;
139 right.nullRow();
140 return true;
141 }
142 fullRowCount = Math.max( fullRowCount, fullRightRowCounter);
143 fullRightRowCounter = 0;
144 }
145 isOuterValid = true;
146 result = left.next();
147 if(result){
148 result = right.first();
149 if(!result){
150 switch(type){
151 case LEFT_JOIN:
152 case FULL_JOIN:
153 isOuterValid = false;
154 right.nullRow();
155 return true;
156 }
157 }else fullRightRowCounter++;
158 }
159
160 }else fullRightRowCounter++;
161 }
162 isBeforeFirst = false;
163 }while(result && !getBoolean());
164 isOuterValid = false;
165 if(type == FULL_JOIN){
166 if(fullRightRowCounter >= isFullNotValid.length){
167 boolean[] temp = new boolean[fullRightRowCounter << 1];
168 System.arraycopy( isFullNotValid, 0, temp, 0, fullRightRowCounter);
169 isFullNotValid = temp;
170 }
171 if(!result){
172 if(fullRowCount == 0){
173 noRow();
174 return false;
175 }
176 if(fullReturnCounter<0) {
177 fullReturnCounter = 0;
178 right.first();
179 left.nullRow();
180 }
181 while(isFullNotValid[fullReturnCounter++]){
182 if(fullReturnCounter >= fullRowCount){
183 noRow();
184 return false;
185 }
186 right.next();
187 }
188 return true;
189 }else
190 isFullNotValid[fullRightRowCounter-1] = result;
191 }
192 if(!result){
193 noRow();
194 }
195 return result;
196 }
197
198
199 void afterLast(){
200 isAfterLast = true;
201 noRow();
202 }
203
204
205 int getRow(){
206 return row;
207 }
208
209
210 final long getRowPosition(){
211 if(rowPositions == null) rowPositions = new LongLongList();
212 rowPositions.add( left.getRowPosition(), right.getRowPosition());
213 return rowPositions.size()-1;
214 }
215
216 final void setRowPosition(long rowPosition) throws Exception {
217 left .setRowPosition( rowPositions.get1((int)rowPosition));
218 right.setRowPosition( rowPositions.get2((int)rowPosition));
219 }
220
221
222 final boolean rowInserted(){
223 return left.rowInserted() || right.rowInserted();
224 }
225
226
227 final boolean rowDeleted(){
228 return left.rowDeleted() || right.rowDeleted();
229 }
230
231
232
235 void nullRow(){
236 left.nullRow();
237 right.nullRow();
238 row = 0;
239 }
240
241
242 void noRow(){
243 isAfterLast = true;
244 left.noRow();
245 right.noRow();
246 row = 0;
247 }
248
249
250 void execute() throws Exception {
251 left.execute();
252 right.execute();
253 }
254
255
256 private boolean getBoolean() throws Exception {
257 return type == CROSS_JOIN || condition.getBoolean();
258 }
259
260
261 static final int CROSS_JOIN = 1;
262 static final int INNER_JOIN = 2;
263 static final int LEFT_JOIN = 3;
264 static final int FULL_JOIN = 4;
265 static final int RIGHT_JOIN = 5;
266 } |
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