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Java > Open Source Codes > org > jaxen > expr > PredicateSet


1 /*
2  * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/PredicateSet.java,v 1.18 2005/04/15 20:24:04 elharo Exp $
3  * $Revision: 1.18 $
4  * $Date: 2005/04/15 20:24:04 $
5  *
6  * ====================================================================
7  *
8  * Copyright (C) 2000-2002 bob mcwhirter & James Strachan.
9  * All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  *
15  * 1. Redistributions of source code must retain the above copyright
16  * notice, this list of conditions, and the following disclaimer.
17  *
18  * 2. Redistributions in binary form must reproduce the above copyright
19  * notice, this list of conditions, and the disclaimer that follows
20  * these conditions in the documentation and/or other materials
21  * provided with the distribution.
22  *
23  * 3. The name "Jaxen" must not be used to endorse or promote products
24  * derived from this software without prior written permission. For
25  * written permission, please contact license@jaxen.org.
26  *
27  * 4. Products derived from this software may not be called "Jaxen", nor
28  * may "Jaxen" appear in their name, without prior written permission
29  * from the Jaxen Project Management (pm@jaxen.org).
30  *
31  * In addition, we request (but do not require) that you include in the
32  * end-user documentation provided with the redistribution and/or in the
33  * software itself an acknowledgement equivalent to the following:
34  * "This product includes software developed by the
35  * Jaxen Project (http://www.jaxen.org/)."
36  * Alternatively, the acknowledgment may be graphical using the logos
37  * available at http://www.jaxen.org/
38  *
39  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
40  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
41  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
42  * DISCLAIMED. IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT
43  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
45  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
46  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
47  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
48  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
49  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50  * SUCH DAMAGE.
51  *
52  * ====================================================================
53  * This software consists of voluntary contributions made by many
54  * individuals on behalf of the Jaxen Project and was originally
55  * created by bob mcwhirter <bob@werken.com> and
56  * James Strachan <jstrachan@apache.org>. For more information on the
57  * Jaxen Project, please see <http://www.jaxen.org/>.
58  *
59  * $Id: PredicateSet.java,v 1.18 2005/04/15 20:24:04 elharo Exp $
60  */
61
62
63
64 package org.jaxen.expr;
65
66 import java.io.Serializable JavaDoc;
67 import java.util.ArrayList JavaDoc;
68 import java.util.Collections JavaDoc;
69 import java.util.Iterator JavaDoc;
70 import java.util.List JavaDoc;
71 import org.jaxen.Context;
72 import org.jaxen.ContextSupport;
73 import org.jaxen.JaxenException;
74 import org.jaxen.function.BooleanFunction;
75
76 public class PredicateSet implements Serializable JavaDoc
77 {
78     private List JavaDoc predicates;
79
80     public PredicateSet()
81     {
82         this.predicates = Collections.EMPTY_LIST;
83     }
84
85     public void addPredicate(Predicate predicate)
86     {
87         if ( this.predicates == Collections.EMPTY_LIST )
88         {
89             this.predicates = new ArrayList JavaDoc();
90         }
91
92         this.predicates.add( predicate );
93     }
94
95     public List JavaDoc getPredicates()
96     {
97         return this.predicates;
98     }
99
100     public void simplify()
101     {
102         Iterator JavaDoc predIter = this.predicates.iterator();
103         Predicate eachPred = null;
104
105         while ( predIter.hasNext() )
106         {
107             eachPred = (Predicate) predIter.next();
108             eachPred.simplify();
109         }
110     }
111
112     public String JavaDoc getText()
113     {
114         StringBuffer JavaDoc buf = new StringBuffer JavaDoc();
115
116         Iterator JavaDoc predIter = this.predicates.iterator();
117         Predicate eachPred = null;
118
119         while ( predIter.hasNext() )
120         {
121             eachPred = (Predicate) predIter.next();
122             buf.append( eachPred.getText() );
123         }
124
125         return buf.toString();
126     }
127
128     // FIXME: Note - this could be *MUCH* more efficient
129 // currently this creates many redundant collections and should halt
130 // evaluation on the first matching item.
131 protected boolean evaluateAsBoolean(List JavaDoc contextNodeSet,
132                                       ContextSupport support) throws JaxenException
133     {
134         List JavaDoc result = evaluatePredicates( contextNodeSet, support );
135
136         return ! result.isEmpty();
137     }
138
139    protected List JavaDoc evaluatePredicates(List JavaDoc contextNodeSet, ContextSupport support)
140             throws JaxenException {
141         // Easy way out (necessary)
142 if (predicates.size() == 0) {
143             return contextNodeSet;
144         }
145         Iterator JavaDoc predIter = predicates.iterator();
146
147         // initial list to filter
148 List JavaDoc nodes2Filter = contextNodeSet;
149         // apply all predicates
150 while(predIter.hasNext()) {
151             nodes2Filter =
152                 applyPredicate((Predicate)predIter.next(), nodes2Filter, support);
153         }
154         
155         return nodes2Filter;
156     }
157    
158     public List JavaDoc applyPredicate(Predicate predicate, List JavaDoc nodes2Filter, ContextSupport support)
159             throws JaxenException {
160         final int nodes2FilterSize = nodes2Filter.size();
161         List JavaDoc filteredNodes = new ArrayList JavaDoc(nodes2FilterSize);
162         // Set up a dummy context with a list to hold each node
163 Context predContext = new Context(support);
164         List JavaDoc tempList = new ArrayList JavaDoc(1);
165         predContext.setNodeSet(tempList);
166         // loop through the current nodes to filter and add to the
167 // filtered nodes list if the predicate succeeds
168 for (int i = 0; i < nodes2FilterSize; ++i) {
169             Object JavaDoc contextNode = nodes2Filter.get(i);
170             tempList.clear();
171             tempList.add(contextNode);
172             predContext.setNodeSet(tempList);
173             // ????
174 predContext.setPosition(i + 1);
175             predContext.setSize(nodes2FilterSize);
176             Object JavaDoc predResult = predicate.evaluate(predContext);
177             if (predResult instanceof Number JavaDoc) {
178                 // Here we assume nodes are in forward or reverse order
179 // as appropriate for axis
180 int proximity = ((Number JavaDoc) predResult).intValue();
181                 if (proximity == (i + 1)) {
182                     filteredNodes.add(contextNode);
183                 }
184             }
185             else {
186                 Boolean JavaDoc includes =
187                     BooleanFunction.evaluate(predResult,
188                                             predContext.getNavigator());
189                 if (includes.booleanValue()) {
190                     filteredNodes.add(contextNode);
191                 }
192             }
193         }
194         return filteredNodes;
195     }
196 }
197
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