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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/DefaultStep.java,v 1.20 2005/09/06 13:41:01 elharo Exp $
3    * $Revision: 1.20 $
4    * $Date: 2005/09/06 13:41:01 $
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: DefaultStep.java,v 1.20 2005/09/06 13:41:01 elharo Exp $
60   */
61  package org.jaxen.expr;
62  
63  import java.util.ArrayList;
64  import java.util.Iterator;
65  import java.util.List;
66  
67  import org.jaxen.Context;
68  import org.jaxen.ContextSupport;
69  import org.jaxen.JaxenException;
70  import org.jaxen.UnsupportedAxisException;
71  import org.jaxen.expr.iter.IterableAxis;
72  import org.jaxen.saxpath.Axis;
73  
74  /***
75   * @deprecated this class will become non-public in the future;
76   *     use the interface instead
77   */
78  public abstract class DefaultStep implements Step
79  {
80      private IterableAxis axis;
81      private PredicateSet predicates;
82  
83      public DefaultStep(IterableAxis axis, PredicateSet predicates)
84      {
85          this.axis = axis;
86          this.predicates = predicates;
87      }
88  
89      public void addPredicate(Predicate predicate)
90      {
91          this.predicates.addPredicate(predicate);
92      }
93  
94      public List getPredicates()
95      {
96          return this.predicates.getPredicates();
97      }
98  
99      public PredicateSet getPredicateSet()
100     {
101         return this.predicates;
102     }
103 
104     public int getAxis()
105     {
106         return this.axis.value();
107     }
108 
109     public IterableAxis getIterableAxis()
110     {
111         return this.axis;
112     }
113 
114     public String getAxisName()
115     {
116         return Axis.lookup(getAxis());
117     }
118 
119     public String getText()
120     {
121         return this.predicates.getText();
122     }
123 
124     public String toString()
125     {
126         return getIterableAxis() + " " + super.toString();
127     }
128 
129     public void simplify()
130     {
131         this.predicates.simplify();
132     }
133 
134     public Iterator axisIterator(Object contextNode, ContextSupport support)
135         throws UnsupportedAxisException
136     {
137         return getIterableAxis().iterator(contextNode, support);
138     }
139 
140     public List evaluate(final Context context) throws JaxenException
141     {
142         final List contextNodeSet  = context.getNodeSet();
143         final IdentitySet unique = new IdentitySet();
144         final int contextSize = contextNodeSet.size();
145 
146         // ???? try linked lists instead?
147         // ???? initial size for these?
148         final ArrayList interimSet = new ArrayList();
149         final ArrayList newNodeSet = new ArrayList();
150         final ContextSupport support = context.getContextSupport();
151             
152         // ???? use iterator instead
153         for ( int i = 0 ; i < contextSize ; ++i )
154         {
155             Object eachContextNode = contextNodeSet.get( i );
156 
157 
158                 /* See jaxen-106. Might be able to optimize this by doing
159                  * specific matching for individual axes. For instance on namespace axis
160                  * we should only get namespace nodes and on attribute axes we only get 
161                  * attribute nodes. Self and parent axes have single members.
162                  * Children, descendant, ancestor, and sibling axes never 
163                  * see any attributes or namespaces
164                  */
165             Iterator axisNodeIter = axis.iterator(eachContextNode, support);
166             while ( axisNodeIter.hasNext() )
167             {
168                 Object eachAxisNode = axisNodeIter.next();
169                 if ( ! unique.contains( eachAxisNode ) )
170                 {
171                     if ( matches( eachAxisNode, support ) )
172                     {
173                         unique.add( eachAxisNode );
174                         interimSet.add( eachAxisNode );
175                     }
176                 }
177             }
178             newNodeSet.addAll(getPredicateSet().evaluatePredicates(
179                               interimSet, support ));
180             interimSet.clear();
181         }
182         return newNodeSet;
183     }
184 
185 }