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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;
67  import java.util.ArrayList;
68  import java.util.Collections;
69  import java.util.Iterator;
70  import java.util.List;
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
77  {
78      private List 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();
90          }
91  
92          this.predicates.add( predicate );
93      }
94  
95      public List getPredicates()
96      {
97          return this.predicates;
98      }
99  
100     public void simplify()
101     {
102         Iterator  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 getText()
113     {
114         StringBuffer buf = new StringBuffer();
115 
116         Iterator  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 contextNodeSet,
132                                       ContextSupport support) throws JaxenException
133     {
134         List result = evaluatePredicates( contextNodeSet, support );
135 
136         return ! result.isEmpty();
137     }
138 
139    protected List evaluatePredicates(List contextNodeSet, ContextSupport support)
140             throws JaxenException {
141         // Easy way out (necessary)
142         if (predicates.size() == 0) {
143             return contextNodeSet;
144         }
145         Iterator predIter = predicates.iterator();
146 
147         // initial list to filter
148         List 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 applyPredicate(Predicate predicate, List nodes2Filter, ContextSupport support)
159             throws JaxenException {
160         final int nodes2FilterSize = nodes2Filter.size();
161         List filteredNodes = new ArrayList(nodes2FilterSize);
162         // Set up a dummy context with a list to hold each node
163         Context predContext = new Context(support);
164         List tempList = new ArrayList(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 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 predResult = predicate.evaluate(predContext);
177             if (predResult instanceof Number) {
178                 // Here we assume nodes are in forward or reverse order
179                 // as appropriate for axis
180                 int proximity = ((Number) predResult).intValue();
181                 if (proximity == (i + 1)) {
182                     filteredNodes.add(contextNode);
183                 }
184             }
185             else {
186                 Boolean includes =
187                     BooleanFunction.evaluate(predResult,
188                                             predContext.getNavigator());
189                 if (includes.booleanValue()) {
190                     filteredNodes.add(contextNode);
191                 }
192             }
193         }
194         return filteredNodes;
195     }
196 }