OpUn


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.mediator.plan ;
24  
25  import java.util.ArrayList  ;
26  
27  import org.xquark.mediator.decomposer.Utils;
28  import org.xquark.mediator.runtime.MediatorException;
29  import org.xquark.xquery.parser.XQueryExpression;
30  
31  public abstract class OpUn extends Operator {
32      // **********************************************************************
33      // * VERSIONING
34      // **********************************************************************
35      private static final String   RCSRevision = "$Revision: 1.5 $";
36      private static final String   RCSName = "$Name:  $";
37      // **********************************************************************
38      // * CLASS VARIABLES
39      // **********************************************************************
40      protected Operator childOperator = null ;
41      
42      // ***********************************************************************
43      // * INITIALIZATION
44      // ***********************************************************************
45      /**
46       *
47       */
48      public OpUn(ExecutionPlan plan, XQueryExpression expression, Operator childOperator) throws MediatorException {
49          super(plan, expression) ;
50          this.childOperator = childOperator ;
51          if (childOperator != null) {
52              childOperator.setParentOperator(this);
53              addPaths(childOperator.getPaths());
54          }
55      }
56      
57      // #############################################################################
58      // VISITOR STUFF
59      // #############################################################################
60  
61      public void accept(OperatorVisitor visitor) throws MediatorException {
62          visitor.visit(this);
63      }
64  
65      // ***********************************************************************
66      // * EXECUTE QUERY
67      // ***********************************************************************
68      /**
69       *
70       */
71      public ResultSet executeQuery(DynamicContext context) throws MediatorException {
72          if (childOperator != null) {
73              OperatorRunnable or = childOperator.getOperatorRunnable(context);
74              or.run() ;
75              return getResultSet(context, or);
76          }
77          return getResultSet(context, null);
78      }
79      
80      /**
81       * @param or
82       * @return
83       */
84      protected abstract ResultSet getResultSet(DynamicContext context, OperatorRunnable or) throws MediatorException;
85  
86      // ***********************************************************************
87      // * METHODS
88      // ***********************************************************************
89      /**
90       *
91       */
92      public Operator getChildOperator() { return childOperator ; }
93      
94      // **********************************************************************
95      // * OPTIMIZE
96      // **********************************************************************
97      /**
98       * If the *exactly* same set of source is used for an operation,
99       * then the subtree can be passed entierely to the source.
100      * Beware of processing this from the leaf to the node.
101      *
102      * <p>Note: If this method is not overloaded or if it returns null,
103      * it means that _this_ node will not be optimized.</p>
104      */
105 //    public Operator optimizeSource() throws MediatorException {
106 //        Operator workexp = childOperator.optimizeSource() ;
107 //        if (workexp != null) childOperator = workexp ;
108 //                
109 //        /*
110 //        if (childalgebra.isSource()) {
111 //            Algebra newnode = mergeWithSub() ;
112 //            return newnode ;
113 //        }
114 //        */
115 //        return null ;
116 //    }
117     
118     /**
119      * Add projections on attributes the soonest as possible in order to
120      * manipulate the less data as possible. As soon an attribute isn't
121      * necessary, it must be unselected (by a projection on the complementary
122      * variables).
123      *
124      * <p>Note: If this method is not overloaded or if it returns null,
125      * it means that _this_ node will not be optimized.</p>
126      */
127 //    public Operator optimizeProjection() throws MediatorException {
128 //        return null ;
129 //    }
130     
131     /**
132      *
133      *
134      * <p>Note: If this method is not overloaded or if it returns null,
135      * it means that _this_ node will not be optimized.</p>
136      */
137 //    public Operator optimizeRestriction() throws MediatorException {
138 //        return null ;
139 //    }
140     
141     
142     /**
143      * If the set of sources handled by this node are exactly the same (order
144      * not important) then return true.
145      *
146      * An AlgUnOp is alway the same value than the value of its children.
147      */
148 //    protected boolean shareSameSources() {
149 //        return childOperator.shareSameSources() ;
150 //    }
151     
152     /**
153      * Return true if the node is of type source. An AlgUnOp is not a source.
154      * @return false.
155      */
156     public boolean isSource() {
157         return false ;
158     }
159     
160     /**
161      * Return all the sources depending of this node.
162      */
163     public ArrayList   getSources() {
164         if (sources == null)
165             sources = childOperator.getSources() ;
166         return sources ;
167     }
168     
169     public void terminate() {
170         if (childOperator != null) 
171             childOperator.terminate();
172     }
173 
174     public void setPrepared() throws MediatorException {
175         if (prepared) return;
176         prepared = true;
177         if (childOperator != null) 
178             childOperator.setPrepared();
179     }
180     
181     public String   toCompleteString(int indent) {
182         StringBuffer   buf = new StringBuffer  () ;
183         buf.append(Utils.makeIndent(indent) + "<" + getClass().getName() + " size=" + size + " id size=" + idsize + " isLet=\"" + islet + "\" valueDepends=\"" + valueDepends + "\" whereDepends=\"" + whereDepends + "\">\n") ;
184         buf.append(Utils.makeIndent(indent + 1) + "<Expression>\n") ;
185         buf.append(Utils.makeIndent(indent + 2) + expression + "\n") ;
186         buf.append(Utils.makeIndent(indent + 1) + "</Expression>\n") ;
187 //        if (variables != null) {
188 //            buf.append(Utils.makeIndent(indent + 1) + "<Variables>\n") ;
189 //            for (int i = 0 ; i < variables.size() ; i ++) {
190 //                buf.append(Utils.makeIndent(indent + 2) + "<Variable>" + variables.get(i) + "</Variable>\n") ;
191 //            }
192 //            buf.append(Utils.makeIndent(indent + 1) + "</Variables>\n") ;
193 //        }
194         if (paths != null) {
195             buf.append(Utils.makeIndent(indent + 1) + "<Paths>\n") ;
196             for (int i = 0 ; i < paths.size() ; i ++) {
197                 buf.append(Utils.makeIndent(indent + 2) + "<Path>" + paths.get(i) + "</Path>\n") ;
198             }
199             buf.append(Utils.makeIndent(indent + 1) + "</Paths>\n") ;
200         }
201         buf.append(Utils.makeIndent(indent + 1) + "<Element>\n") ;
202         if (this.childOperator != null) buf.append(this.childOperator.toCompleteString(indent + 2)) ;
203         buf.append(Utils.makeIndent(indent + 1) + "</Element>\n") ;        
204         buf.append(Utils.makeIndent(indent) + "</" + getClass().getName() + ">\n") ;
205         return buf.toString() ;
206     }
207 }
208
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