RemoveProjectVisitor


1   /*
2    * This file belongs to the XQuark distribution.
3    * Copyright (C) 2003 Universite de Versailles Saint-Quentin.
4    * 
5    * This program is free software; you can redistribute it and/or
6    * modify it under the terms of the GNU Lesser General Public
7    * License as published by the Free Software Foundation; either
8    * version 2.1 of the License, or (at your option) any later version.
9    * 
10   * This program is distributed in the hope that it will be useful,
11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   * Lesser General Public License for more details.
14   * 
15   * You should have received a copy of the GNU Lesser General Public
16   * License along with this program; if not, write to the Free Software
17   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307.
18   * You can also get it at http://www.gnu.org/licenses/lgpl.html
19   * 
20   * For more information on this software, see http://www.xquark.org.
21   */
22  
23  package org.xquark.extractor.algebra;
24  
25  import java.util.*;
26  
27  import org.xquark.extractor.common.Debug;
28  import org.xquark.extractor.common.SqlWrapperException;
29  import org.xquark.xquery.parser.XQueryExpression;
30  
31  public final class RemoveProjectVisitor extends DefaultAlgebraVisitor {
32      private static final String   RCSRevision = "$Revision: 1.5 $";
33      private static final String   RCSName = "$Name:  $";
34  
35      private RemoveProjectReplaceVisitor _rprv;
36      private RemoveProjectGoUpVisitor _rpguv;
37  
38      private Stack _scopeStack = new Stack();
39  
40      public void reinit() {
41          _scopeStack.clear();
42          createScope();
43      }
44  
45      public RemoveProjectVisitor() {
46      }
47  
48      //    public RemoveProjectVisitor(RemoveProjectGoUpVisitor rpguv) {
49      //        setGoUpVisitor(rpguv);
50      //    }
51  
52      /**
53      Access method for the _rprv property.
54      
55      @return   the current value of the _rprv property
56       */
57      public RemoveProjectGoUpVisitor getGoUpVisitor() {
58          if (null == _rpguv) {
59              _rpguv = new RemoveProjectGoUpVisitor();
60          }
61          return _rpguv;
62      }
63  
64      /**
65      Sets the value of the _replaceVisitor property.
66      
67      @param aReplaceVisitor the new value of the _replaceVisitor property
68       */
69      public void setGoUpVisitor(RemoveProjectGoUpVisitor rpguv) {
70          _rpguv = rpguv;
71      }
72  
73      private boolean isDeletePermitted() {
74          //        Trace.enter(this, "isDeletePermitted()");
75          boolean retVal = ((Scope) _scopeStack.peek())._deletePermited;
76          //        Trace.exit(this, "isDeletePermitted()", retVal.toString());
77          return retVal;
78      }
79  
80      private void permitDelete(Expression node, boolean permit) {
81          //Trace.enter(this, "permitDelete(boolean permit)", node.toString() + "\t" + (permit ? "true" : "false"));
82          Scope currentScope = (Scope) _scopeStack.peek();
83          currentScope._deletePermited = permit;
84          currentScope._node = node;
85          //Trace.exit(this, "permitDelete(boolean permit)", node.toString() + "\t" + (permit ? "true" : "false"));
86      }
87  
88      private Expression currentPermiter() {
89          //Trace.enter(this, "currentPermiter()");
90          Scope currentScope = (Scope) _scopeStack.peek();
91          Debug.assertTrue(currentScope._deletePermited, "currentScope._deletePermited");
92          //Trace.exit(this, "currentPermiter()");
93          return currentScope._node;
94      }
95  
96      private void createScope() {
97          _scopeStack.push(new Scope());
98      }
99  
100     private Scope currentScope() {
101         return (Scope) _scopeStack.peek();
102     }
103 
104     private void leaveScope() {
105         //Trace.enter(this, "leaveScope()");
106         RenameRelation rr = currentScope()._unresolvedRenameRelation;
107         if (null != rr) {
108             if (null != rr.getFather() && !(rr.getOperand() instanceof Table)) {
109                 /* remove this RenameRelation*/
110                 //Trace.message(this, "leaveScope()", "Removing  unresoled RenameRelation...");
111                 /* make up map*/
112                 HashMap map = new HashMap();
113                 Object   tableInstance = null;
114                 Set vtis = rr.visibleTableInstances();
115                 int visibleTableInstancesNumber = vtis.size();
116 
117                 if (0 == visibleTableInstancesNumber) {
118                     Debug.assertTrue(false, "internal logic error");
119                 } else if (1 == visibleTableInstancesNumber) {
120                     tableInstance = (Expression) vtis.toArray()[0];
121                     if (!(tableInstance instanceof RenameRelation)) {
122                         tableInstance = new NullPointer();
123                     }
124                     map.put(rr, tableInstance);
125                 } else {
126                     Debug.nyi("remove RenameRelation");
127                 }
128 
129                 /* */
130                 getGoUpVisitor().setMap(map);
131                 getGoUpVisitor().setEndNode(currentPermiter());
132                 //Trace.message(this, "replace map", getGoUpVisitor().printMap());
133 
134                 Expression father = rr.getFather();
135                 boolean replaced = father.replaceChild(rr, rr.getOperand());
136                 Debug.assertTrue(replaced, "replaced");
137                 rr.setFather(null);
138                 //Trace.message(this, "leaveScope()", "RenameRelation removed.");
139                 father.accept(_rpguv);
140             }
141         }
142 
143         _scopeStack.pop();
144         //Trace.exit(this, "leaveScope()");
145     }
146 
147     //public void visit(Expression arg) throws SqlWrapperException;
148 
149     //    public void visit(BinaryOperator arg) throws SqlWrapperException {
150     //        Trace.enter(this,"visit(BinaryOperator arg)",arg.pprint());
151     //        Trace.exit(this,"visit(BinaryOperator arg)",arg.pprint());
152     //    }
153 
154     public void visit(BinaryAlgebra arg) throws SqlWrapperException {
155         //Trace.enter(this, "visit(BinaryAlgebra arg)", arg.pprint());
156         /* implementation or Merg, Union, Intersect and difference, but not for OuterJoin */
157         /* here the process of deepth-first serach re-start */
158         createScope();
159         arg.getLeftOperand().accept(this);
160         leaveScope();
161 
162         createScope();
163         arg.getRightOperand().accept(this);
164         leaveScope();
165 
166         //Trace.exit(this, "visit(BinaryAlgebra arg)", arg.pprint());
167     }
168 
169     public void visit(BinaryAtomicOp arg) throws SqlWrapperException {
170         //Trace.enter(this, "visit(BinaryAtomicOp arg)", arg.pprint());
171 
172         createScope();
173         arg.getLeftOperand().accept(this);
174         leaveScope();
175 
176         createScope();
177         arg.getRightOperand().accept(this);
178         leaveScope();
179 
180         //Trace.exit(this, "visit(BinaryAtomicOp arg)", arg.pprint());
181     }
182 
183     public void visit(BinOpOuterJoin arg) throws SqlWrapperException {
184         //Trace.enter(this, "visit(BinOpOuterJoin arg)", arg.pprint());
185 
186         arg.getLeftOperand().accept(this);
187         arg.getRightOperand().accept(this);
188 
189         //Trace.exit(this, "visit(BinOpOuterJoin arg)", arg.pprint());
190     }
191 
192     public void visit(SortSpecification arg) throws SqlWrapperException {
193         //Trace.enter(this, "visit(SortSpecification arg)", arg.pprint());
194         Expression sortExpr = arg.getSortExpression();
195         sortExpr.accept(this);
196         //Trace.exit(this, "visit(SortSpecification arg)", arg.pprint());
197     }
198 
199     public void visit(RenameRelation arg) throws SqlWrapperException {
200         //Trace.enter(this, "visit(RenameRelation arg)", arg.pprint());
201 
202         /** @todo within a scope, there might be serverl  unresolved RenameRelation.
203          *  Scope class should keep a list of  unresolved RenameRelation  instead of one*/
204         if (!(arg.getOperand() instanceof Table || arg.getOperand() instanceof UnOpProject)) {
205             /* when the operand is Table, this RenameRelation should not be removed
206             *  when the operand is UnOpProject, this RenameRelation should have been
207             *  removed with the UnOpProject */
208             currentScope()._unresolvedRenameRelation = arg;
209             //Trace.message(this, "visit(RenameRelation arg)", "unresolved RenameRelation added to current scope");
210         }
211 
212         Expression operand = arg.getOperand();
213         operand.accept(this);
214 
215         //Trace.exit(this, "visit(RenameRelation arg)", arg.pprint());
216     }
217 
218     public void visit(Table arg) throws SqlWrapperException {
219         //Trace.enter(this, "visit(Table arg)", arg.pprint());
220         /* here, the process reach a leaf node */
221         //Trace.exit(this, "visit(Table arg)", arg.pprint());
222     }
223 
224     public void visit(Join arg) throws SqlWrapperException {
225         //Trace.enter(this, "visit(Join arg)", arg.pprint());
226 
227         List list = arg.getPredicateList();
228         if (null != list) {
229             Expression expr = null;
230             for (int i = 0; i < list.size(); i++) {
231                 expr = (Expression) list.get(i);
232                 createScope();
233                 expr.accept(this);
234                 leaveScope();
235             }
236         }
237 
238         list = arg.getOperands();
239         Debug.assertTrue(null != list, "null!=list");
240         Expression expr = null;
241         for (int i = 0; i < list.size(); i++) {
242             expr = (Expression) list.get(i);
243             expr.accept(this);
244         }
245 
246         //Trace.exit(this, "visit(Join arg)", arg.pprint());
247     }
248 
249     public void visit(UnaryAlgebra arg) throws SqlWrapperException {
250         //Trace.enter(this, "visit(UnaryAlgebra arg)", arg.pprint());
251 
252         List list = arg.getParameterList();
253         if (null != list) {
254             Expression expr = null;
255             for (int i = 0; i < list.size(); i++) {
256                 expr = (Expression) list.get(i);
257                 createScope();
258                 expr.accept(this);
259                 leaveScope();
260             }
261         }
262 
263         Expression operand = arg.getOperand();
264         if (isDeletePermitted()) {
265             /* check if this operater permet to delete a underlying UnOpProject*/
266             List opposers = vote(arg);
267             if (null == opposers) {
268                 /* do nothing */
269             } else {
270                 permitDelete(arg, false);
271             }
272         }
273         operand.accept(this);
274 
275         //Trace.exit(this, "visit(UnaryAlgebra arg)", arg.pprint());
276     }
277 
278     public void visit(UnaryAtomicOp arg) throws SqlWrapperException {
279         //Trace.enter(this, "visit(UnaryAtomicOp arg)", arg.pprint());
280         arg.getOperand().accept(this);
281         //Trace.exit(this, "visit(UnaryAtomicOp arg)", arg.pprint());
282     }
283 
284     public void visit(UnOpAggregate arg) throws SqlWrapperException {
285         //Trace.enter(this, "visit(UnOpAggregate arg)", arg.pprint());
286 
287         Expression operand = arg.getOperand();
288 
289         /* check if this UnOpAggregate permet to delete a underlying UnOpProject*/
290         createScope();
291         List opposers = vote(arg);
292         if (null == opposers) {
293             permitDelete(arg, true);
294             //Trace.message(this, "visit(UnOpAggregate arg)", "removal of project is permitted !");
295         }
296         operand.accept(this);
297         leaveScope();
298 
299         List itemList = arg.getItemList();
300         Expression item = null;
301         ;
302         for (int i = 0; i < itemList.size(); i++) {
303             createScope();
304             item = (Expression) itemList.get(i);
305             item.accept(this);
306             leaveScope();
307         }
308 
309         //Trace.exit(this, "visit(UnOpAggregate arg)", arg.pprint());
310     }
311 
312     public void visit(UnOpExists arg) throws SqlWrapperException {
313         //Trace.enter(this, "visit(UnOpExists arg)", arg.pprint());
314         createScope();
315         permitDelete(arg, true);
316         arg.getOperand().accept(this);
317         leaveScope();
318         //Trace.exit(this, "visit(UnOpExists arg)", arg.pprint());
319     }
320 
321     public void visit(UnOpProject arg) throws SqlWrapperException {
322         //Trace.enter(this, "visit(UnOpProject arg)", arg.pprint());
323 
324         Expression operand = arg.getOperand();
325 
326         /* visit its operand */
327         //Trace.message(this, "visit(UnOpProject arg)", "Visiting its operand...");
328         createScope();
329         /* check if this UnOpProject permet to delete a underlying UnOpProject*/
330         List opposers = vote(arg);
331         if (null == opposers) {
332             permitDelete(arg, true);
333             //Trace.message(this, "visit(UnOpProject arg)", "removal of project is permitted !");
334         }
335         operand.accept(this);
336         leaveScope();
337 
338         /*visit its items */
339         //Trace.message(this, "visit(UnOpProject arg)", "Visiting its item list...");
340         List itemList = arg.getItemList();
341         Expression item = null;
342         ;
343         for (int i = 0; i < itemList.size(); i++) {
344             createScope();
345             item = (Expression) itemList.get(i);
346             item.accept(this);
347             leaveScope();
348         }
349 
350         /* remove itself if possible */
351         if (isDeletePermitted()) {
352             if (!arg.getDistinct()) {
353                 removeProject(arg, currentPermiter());
354             } else if (currentPermiter() instanceof UnOpAggregate) {
355                 /* @todo verify that currentPermiter contains only aggregation funtions like :
356                  *  aggrFunc(attr), but not aggrFunc(*)
357                  */
358                 if (1 == arg.getItemList().size()) {
359                     removeProject(arg, currentPermiter());
360                     ((UnOpAggregate) currentPermiter()).distinctAggregation();
361 
362                 } else {
363                     Debug.nyi("1 != arg.getItemList().size()");
364                 }
365             }
366         }
367 
368         //Trace.exit(this, "visit(UnOpProject arg)", arg.pprint());
369     }
370 
371     private void removeProject(UnOpProject project, Expression permittingNode) {
372         //Trace.enter(this, "removeProject(UnOpProject project, Expression permittingNode)");
373 
374         //Trace.message(this, "visit(UnOpProject arg)", "starting GoUpVisitor..");
375         HashMap map = makeMap(project);
376         getGoUpVisitor().setMap(map);
377         getGoUpVisitor().setEndNode(permittingNode);
378         //Trace.message(this, "replace map", getGoUpVisitor().printMap());
379 
380         Expression father = project.getFather();
381 
382         boolean replaced = father.replaceChild(project, project.getOperand());
383         Debug.assertTrue(replaced, "replaced");
384 
385         project.setFather(null);
386         //Trace.message(this, "visit(UnOpProject arg)", "project removed.");
387         father.accept(_rpguv);
388 
389         //Trace.exit(this, "removeProject(UnOpProject project, Expression permittingNode)");
390     }
391 
392     private List vote(Expression arg) {
393         //Trace.enter(this, "vote(Expression oprtr)", arg.pprint());
394 
395         //Trace.exit(this, "vote(Expression oprtr)", arg.pprint());
396         return null;
397     }
398 
399     private List vote(UnOpProject arg) {
400         //Trace.enter(this, "vote(Expression oprtr)", arg.pprint());
401         /** @todo  */
402         List retVal = null;
403         //Trace.exit(this, "vote(Expression oprtr)", arg.pprint());
404         return retVal;
405     }
406 
407     private HashMap makeMap(UnOpProject arg) {
408         //Trace.enter(this, "makeMap(UnOpProject arg))", arg.pprint());
409 
410         HashMap retVal = new HashMap();
411         List itemList = arg.getItemList();
412         Expression item = null;
413         String   attrName = null;
414         AttributeExpression attrExpr = null;
415         Expression replacer = null;
416         XQueryExpression originalXExpr = null;
417 
418         for (int i = 0; i < itemList.size(); i++) {
419             item = (Expression) itemList.get(i);
420             attrName = item.getName();
421             attrExpr = new AttributeExpression(null, attrName);
422 
423             //            originalXExpr = item.getOrginalXExpr();
424             //            Debug.assertTrue(null != originalXExpr, "null != originalXExpr" + item.pprint());
425 
426             replacer = findReplacer(item);
427             retVal.put(attrExpr, replacer);
428         }
429         //Trace.exit(this, "makeMap(UnOpProject arg))", arg.pprint());
430         return retVal;
431     }
432 
433     private Expression findReplacer(Expression item) {
434         //Trace.enter(this, "findReplacer(Expression item)", item.pprint());
435 
436         Expression retVal = null;
437 
438         if (item instanceof RenameItem) {
439             retVal = ((RenameItem) item).getOperand();
440             retVal = findReplacer(retVal);
441         }
442         //        else  if (item instanceof AttributeExpression) {
443         //            retVal = ((AttributeExpression)item).getUnderlyinExpr();
444         //            if (retVal instanceof Attribute) {
445         //                /* item is the first AttributeExpression who refer a Attribute */
446         //                retVal = item;
447         //            }
448         //            retVal = item;
449         //        }
450         else {
451             retVal = item;
452             //            Debug.assertTrue(false,"internal logic error");
453         }
454 
455         //Trace.exit(this, "findReplacer(Expression item)", item.pprint());
456         return retVal;
457     }
458 
459     class Scope {
460         private static final String   RCSRevision = "$Revision: 1.5 $";
461         private static final String   RCSName = "$Name:  $";
462 
463         boolean _deletePermited = false;
464         Expression _node = null;
465         RenameRelation _unresolvedRenameRelation = null;
466         Scope() {
467         }
468         Scope(Expression node, boolean deletePermited) {
469             _node = node;
470             _deletePermited = deletePermited;
471         }
472     }
473 }
474
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags