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Java > Open Source Codes > org > xquark > mediator > algebra > AlgUnion


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.algebra;
24
25 import org.xquark.mediator.plan.*;
26 import org.xquark.mediator.runtime.MediatorException;
27 import org.xquark.xquery.parser.Variable;
28 import org.xquark.xquery.parser.XQueryExpression;
29
30 /**
31  * This class represent a terminal leaf of the dependancy tree on first step
32  * of creation (before atomization).
33  *
34  */
35 public class AlgUnion extends Algebra {
36     // **********************************************************************
37 // * VERSIONING
38 // **********************************************************************
39 private static final String JavaDoc RCSRevision = "$Revision: 1.5 $";
40     private static final String JavaDoc RCSName = "$Name: $";
41     // **********************************************************************
42 // * CLASS VARIABLES
43 // **********************************************************************
44
45     // ************************************************************************
46 // * INITIALIZATION
47 // ************************************************************************
48 /**
49      *
50      * @param typevisitor
51      * @param expression
52      * @param var
53      * @param parent
54      */
55     public AlgUnion(XQueryExpression expression, Variable var, AlgebraManager depmanager, boolean islet) throws MediatorException {
56         super(expression, var, depmanager, islet);
57         fillVarLists();
58     }
59
60     // ******************************************************************
61 // * METHODS
62 // ******************************************************************
63
64     // ******************************************************************
65 // * CREATE EXECUTION PLAN
66 // ******************************************************************
67 /**
68      *
69      * @param plan
70      * @return
71      */
72     public Operator createOperator(ExecutionPlan plan) throws MediatorException {
73
74         //if (true) throw new MediatorException("createAlgebra not supported in DepArithFunction");
75 Operator operator = null;
76
77         if (algChildren != null) {
78             Operator[] operators = new Operator[algChildren.size()];
79             for (int i = 0; i < algChildren.size(); i++) {
80                 operators[i] = ((Algebra) algChildren.get(i)).createOperator(plan);
81             }
82             operator = new OpUnion(plan, operators);
83         } else
84             operator = new OpEval(plan, this, null, hasIdentifier);
85         operator.isLet(islet);
86         return operator;
87     }
88
89     public Object JavaDoc clone() throws CloneNotSupportedException JavaDoc {
90         AlgUnion newobj = (AlgUnion) super.clone();
91         return newobj;
92     }
93
94     public void execute(ExecutionPlan plan) throws MediatorException {
95     }
96
97     // ******************************************************************
98 // * DEBUGGING
99 // ******************************************************************
100 }
101
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