CanonizeVisitor


1   /*
2    * This file belongs to the XQuark distribution.
3    * Copyright (C) 2003 Universite de Versailles Saint-Quentin.
4    * Copyright (C) 2003 XQuark Group.
5    * 
6    * This program is free software; you can redistribute it and/or
7    * modify it under the terms of the GNU Lesser General Public
8    * License as published by the Free Software Foundation; either
9    * version 2.1 of the License, or (at your option) any later version.
10   * 
11   * This program is distributed in the hope that it will be useful,
12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   * Lesser General Public License for more details.
15   * 
16   * You should have received a copy of the GNU Lesser General Public
17   * License along with this program; if not, write to the Free Software
18   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307.
19   * You can also get it at http://www.gnu.org/licenses/lgpl.html
20   * 
21   * For more information on this software, see http://www.xquark.org.
22   */
23  
24  package org.xquark.xquery.normalize;
25  
26  import java.util.ArrayList  ;
27  import java.util.HashMap  ;
28  import java.util.Stack  ;
29  
30  import org.xquark.xquery.parser.*;
31  import org.xquark.xquery.parser.util.Constants;
32  import org.xquark.xquery.typing.TypeVisitor;
33  
34  public class CanonizeVisitor extends DefaultParserVisitor {
35  
36      private static final String   RCSRevision = "$Revision: 1.4 $";
37      private static final String   RCSName = "$Name:  $";
38  
39      private Stack   parents = null;
40      private Stack   FLWRParents = null;
41      private XQueryExpression resultExpr = null;
42  
43      private ArrayList   QDB = null;
44      private XQueryExpression QMEM = null;
45      private int inReturn = 0;
46      private int inWhere = 0;
47      private Variable inVarDef = null;
48  
49      protected TypeVisitor typeVisitor = null;
50  
51      //  public CanonizeVisitor()
52      public CanonizeVisitor(TypeVisitor typeVisitor) {
53          parents = new Stack  ();
54          FLWRParents = new Stack  ();
55          this.typeVisitor = typeVisitor;
56      }
57  
58      public XQueryExpression getResult() {
59          return resultExpr;
60      }
61      public ArrayList   getQDB() {
62          return QDB;
63      }
64      public XQueryExpression getQMEM() {
65          return QMEM;
66      }
67  
68      // visitors
69  
70      public void visit(Element arg) throws XQueryException {
71          resultExpr = null;
72          parents.push(arg);
73          ArrayList   attributes = arg.getAttributes();
74          if (attributes != null) {
75              for (int i = 0; i < attributes.size(); i++) {
76                  XQueryExpression expri = (XQueryExpression) attributes.get(i);
77                  expri.accept(this);
78                  while (resultExpr != null) {
79                      attributes.set(i, resultExpr);
80                      expri = (XQueryExpression) attributes.get(i);
81                      resultExpr = null;
82                      expri.accept(this);
83                  }
84              }
85          }
86          ArrayList   subExpressions = arg.getSubExpressions();
87          if (subExpressions != null) {
88              for (int i = 0; i < subExpressions.size(); i++) {
89                  XQueryExpression expri = (XQueryExpression) subExpressions.get(i);
90                  expri.accept(this);
91                  while (resultExpr != null) {
92                      subExpressions.set(i, resultExpr);
93                      expri = (XQueryExpression) subExpressions.get(i);
94                      resultExpr = null;
95                      expri.accept(this);
96                  }
97              }
98          }
99          parents.pop();
100     }
101 
102     public void visit(FLWRExpression arg) throws XQueryException {
103         resultExpr = null;
104         int i, j, k;
105         // test if it has a parent FLWR
106         if (inReturn > 0 && !FLWRParents.isEmpty()) {
107             FLWRExpression parentFLWRExpr = (FLWRExpression) FLWRParents.peek();
108             // look at dependencies between variables! (LATER!!!)
109             // create new variable
110             Variable var = typeVisitor.getStaticContext().createVariable(Constants.OUTERLET_BINDINGTYPE, arg, Variable.CAN_CREATOR);
111             parentFLWRExpr.addVariable(var);
112             XQueryExpression retClause = parentFLWRExpr.getReturnClause();
113             if (retClause == arg)
114                 parentFLWRExpr.setReturnClause(var);
115             else {
116                 // substiture FLWR by var in it's parent
117                 HashMap   map = new HashMap  ();
118                 map.put(arg, var);
119                 retClause.substitute(map, typeVisitor);
120             }
121             var.accept(typeVisitor);
122             var.accept(this);
123             return;
124         }
125 
126         parents.push(arg);
127         FLWRParents.push(arg);
128 
129         XQueryExpression whereExpr = arg.getWhereClause();
130         if (whereExpr != null) {
131             inWhere++;
132             whereExpr.accept(this);
133             inWhere--;
134             whereExpr = arg.getWhereClause();
135         }
136 
137         XQueryExpression returnExpr = arg.getReturnClause();
138         inReturn++;
139         returnExpr.accept(this);
140         inReturn--;
141         returnExpr = arg.getReturnClause();
142 
143         //HintTree hinttree = arg.getHintTree();
144         //ArrayList orderby = arg.getOrderBy();
145         /*
146         for (i=0;i<orderby.size();i++) {
147             XQueryExpression orderbyi = (XQueryExpression)orderby.get(i);
148             inReturn++;
149             orderbyi.accept(this);
150             inReturn--;
151         }
152         */
153         ArrayList   variables = arg.getVariables();
154         Variable tmpVar = null;
155         int varsize = variables.size();
156         for (i = 0; i < varsize; i++) {
157             tmpVar = (Variable) variables.get(i);
158             Variable tmpVarDef = inVarDef;
159             inVarDef = tmpVar;
160             tmpVar.accept(this);
161             inVarDef = tmpVarDef;
162         }
163 
164         ArrayList   qdb = new ArrayList  ();
165         ArrayList   forvarlist = new ArrayList  ();
166         ArrayList   letvarlist = new ArrayList  ();
167         // ArrayList usedvarlist = new ArrayList();
168         // get variables used in return clause
169         // put variables in different lists
170         for (i = 0; i < variables.size(); i++) {
171             tmpVar = (Variable) variables.get(i);
172             if (tmpVar.getBindingType() == Constants.OUTERLET_BINDINGTYPE)
173                 letvarlist.add(tmpVar);
174             else
175                 forvarlist.add(tmpVar);
176         }
177 
178         // XQueryExpressionSequence tmpSeq = new XQueryExpressionSequence(usedvarlist,typeVisitor);
179         XQueryExpressionSequence tmpSeq = new XQueryExpressionSequence(forvarlist, arg.getParentModule());
180         tmpSeq.setParenthesis(true);
181         // change   23/01/2003
182         //FLWRExpression tmpFLWR = new FLWRExpression(forvarlist, orderby, whereExpr, tmpSeq, typeVisitor);
183         FLWRExpression tmpFLWR = new FLWRExpression(forvarlist, arg.getHintTree(), arg.getOrderBy(), whereExpr, tmpSeq, arg.getParentModule());
184         tmpFLWR.setParentModule(arg.getParentModule());
185         tmpVar = typeVisitor.getStaticContext().createVariable(Constants.LET_BINDINGTYPE, tmpFLWR, Variable.CAN_CREATOR);
186         qdb.add(tmpVar);
187         XQueryExpression qmem = returnExpr;
188 
189         ArrayList   allinnerqdb = new ArrayList  ();
190         for (i = 0; i < letvarlist.size(); i++) {
191             Variable letVarListi = (Variable) letvarlist.get(i);
192             FLWRExpression letVarListiExpr = (FLWRExpression) letVarListi.getExpression();
193             letVarListiExpr.accept(this);
194             ArrayList   innerqdb = QDB;
195             XQueryExpression innerqmem = QMEM;
196             // put depends
197             ArrayList   vars = letVarListiExpr.getVariables();
198             if (!vars.isEmpty()) {
199                 ArrayList   dependids = new ArrayList  ();
200                 for (j = 0; j < vars.size(); j++) {
201                     Variable varj = (Variable) vars.get(j);
202                     if (varj.getBindingType() == Constants.FOR_BINDINGTYPE)
203                         dependids.add(varj);
204                 }
205                 if (letVarListiExpr.getReturnClause().getDependIDs() == null && !dependids.isEmpty())
206                     letVarListiExpr.getReturnClause().setDependIDs(dependids);
207             }
208 
209             // add for variables from qdb into innerqmem
210             for (j = 0; j < innerqdb.size(); j++) {
211                 Variable innerQdbVari = (Variable) innerqdb.get(j);
212                 FLWRExpression innerQdbVariExpr = (FLWRExpression) innerQdbVari.getExpression();
213                 for (k = 0; k < qdb.size(); k++) {
214                     Variable qdbVari = (Variable) qdb.get(k);
215                     XQueryExpression qdbVariExpr = qdbVari.getExpression();
216                     tmpVar = typeVisitor.getStaticContext().createVariable(Constants.FOR_BINDINGTYPE, qdbVari, Variable.CAN_CREATOR);
217                     innerQdbVariExpr.insertVariable(tmpVar);
218                 }
219             }
220             // add innerqdb to allinnerqdb
221             allinnerqdb.addAll(innerqdb);
222             // replace in qmem variable by innerqmem
223             // handle special case when entire return expression must be replaced
224             if (qmem == letVarListi) {
225                 arg.setReturnClause(innerqmem);
226                 qmem = arg.getReturnClause();
227             } else {
228                 ArrayList   parentList = letVarListi.getParentExpression();
229                 HashMap   map = new HashMap  ();
230                 map.put(letVarListi, innerqmem);
231                 for (j = 0; j < parentList.size(); j++) {
232                     XQueryExpression parenti = (XQueryExpression) parentList.get(j);
233                     parenti.substitute(map, typeVisitor);
234                 }
235             }
236         }
237 
238         // add allinnerqdb to qdb
239         qdb.addAll(allinnerqdb);
240         // put skolems
241         if (letvarlist.size() > 0) {
242             ArrayList   tmpList = new ArrayList  (forvarlist.size());
243             for (i = 0; i < forvarlist.size(); i++) {
244                 Variable var = (Variable) forvarlist.get(i);
245                 // change   27/03/2002
246                 if (var.getBindingType() != Constants.LET_BINDINGTYPE)
247                     tmpList.add(var);
248             }
249             qmem.putSkolemIDs(tmpList);
250         }
251 
252         // set return values
253         QDB = qdb;
254         QMEM = qmem;
255 
256         FLWRParents.pop();
257         parents.pop();
258     }
259 
260     public void visit(Variable arg) throws XQueryException {
261         resultExpr = null;
262         parents.push(arg);
263         if (inReturn > 0) {
264             if (inVarDef != null) {
265                 XQueryExpression expr = arg.getExpression();
266                 expr.accept(this);
267             }
268         }
269         parents.pop();
270     }
271 
272     public void visit(XQueryBinaryOperatorExpression arg) throws XQueryException {
273         resultExpr = null;
274         parents.push(arg);
275         XQueryExpression tmpExpr = arg.getExpression1();
276         tmpExpr.accept(this);
277         while (resultExpr != null) {
278             arg.setExpression1(resultExpr);
279             tmpExpr = arg.getExpression1();
280             resultExpr = null;
281             tmpExpr.accept(this);
282         }
283         tmpExpr = arg.getExpression2();
284         tmpExpr.accept(this);
285         while (resultExpr != null) {
286             arg.setExpression2(resultExpr);
287             tmpExpr = arg.getExpression2();
288             resultExpr = null;
289             tmpExpr.accept(this);
290         }
291         parents.pop();
292     }
293     //  public void visit(XQueryBooleanOperatorExpression arg) throws XQueryException;
294 
295     public void visit(XQueryModule arg) throws XQueryException {
296         // TODO danger expressions must be of size 1
297         ArrayList   expressions = arg.getExpressions();
298         if (expressions != null && expressions.size() == 1)
299             ((XQueryExpression)expressions.get(0)).accept(this);
300         else
301             resultExpr = null;
302     }
303 
304     public void visit(XQueryExpression arg) throws XQueryException {
305         resultExpr = null;
306     }
307 
308     public void visit(XQueryExpressionSequence arg) throws XQueryException {
309         resultExpr = null;
310         parents.push(arg);
311         ArrayList   subExpressions = arg.getSubExpressions();
312         ArrayList   newSubExpressions = new ArrayList  ();
313         XQueryExpression rexExpr = null;
314         if (subExpressions != null) {
315             for (int i = 0; i < subExpressions.size(); i++) {
316                 XQueryExpression expri = (XQueryExpression) subExpressions.get(i);
317                 expri.accept(this);
318                 while (resultExpr != null) {
319                     subExpressions.set(i, resultExpr);
320                     expri = (XQueryExpression) subExpressions.get(i);
321                     resultExpr = null;
322                     expri.accept(this);
323                 }
324             }
325         }
326         parents.pop();
327     }
328 
329     public void visit(XQueryUnaryOperatorExpression arg) throws XQueryException {
330         resultExpr = null;
331         parents.push(arg);
332         XQueryExpression expr = arg.getExpression();
333         expr.accept(this);
334         while (resultExpr != null) {
335             arg.setExpression(resultExpr);
336             expr = arg.getExpression();
337             resultExpr = null;
338             expr.accept(this);
339         }
340         parents.pop();
341     }
342 
343 }
344
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