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1   /*
2    * $Header$
3    * $Revision: 1268 $
4    * $Date: 2006-12-10 07:32:14 -0800 (Sun, 10 Dec 2006) $
5    *
6    * ====================================================================
7    *
8    * Copyright 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 are
13   * met:
14   * 
15   *   * Redistributions of source code must retain the above copyright
16   *     notice, this list of conditions and the following disclaimer.
17   * 
18   *   * Redistributions in binary form must reproduce the above copyright
19   *     notice, this list of conditions and the following disclaimer in the
20   *     documentation and/or other materials provided with the distribution.
21   * 
22   *   * Neither the name of the Jaxen Project nor the names of its
23   *     contributors may be used to endorse or promote products derived 
24   *     from this software without specific prior written permission.
25   * 
26   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
27   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
29   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
30   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37   *
38   * ====================================================================
39   * This software consists of voluntary contributions made by many 
40   * individuals on behalf of the Jaxen Project and was originally 
41   * created by bob mcwhirter <bob@werken.com> and 
42   * James Strachan <jstrachan@apache.org>.  For more information on the 
43   * Jaxen Project, please see <http://www.jaxen.org/>.
44   * 
45   * $Id: Step.java 1268 2006-12-10 15:32:14Z elharo $
46   */
47  
48  package org.jaxen.expr;
49  
50  import java.util.Iterator;
51  import java.util.List;
52  
53  import org.jaxen.Context;
54  import org.jaxen.ContextSupport;
55  import org.jaxen.JaxenException;
56  import org.jaxen.UnsupportedAxisException;
57  
58  /**
59   * <p>Represents a location step in a LocationPath. The node-set selected by 
60   * the location step is the node-set that results from generating an initial 
61   * node-set from the axis and node-test, and then filtering that node-set by 
62   * each of the predicates in turn.</p>
63   * 
64   * <p>
65   * The initial node-set consists of the nodes having the relationship to the 
66   * context node specified by the axis, and having the node type and expanded-name 
67   * specified by the node test.</p>
68   */
69  public interface Step extends Predicated
70  {
71  
72      /**
73       * Performs the node-test part of evaluating the step for the given node
74       * (which must be on the axis).
75       * 
76       * @return true if the node matches this step; false if it doesn't
77       */    
78      boolean matches(Object node,
79                      ContextSupport contextSupport) throws JaxenException;
80  
81      /**
82       * Returns a <code>String</code> containing the XPath expression.
83       * 
84       * @return the text form of this step
85       */
86      String getText();
87  
88      /**
89       * Simplifies the XPath step. In practice, this is usually a noop.
90       * Jaxen does not currently perform any simplification.
91       */
92      void simplify();
93  
94      /**
95       * Get an identifier for the current axis.
96       * 
97       * @return the axis identifier
98       * @see org.jaxen.saxpath.Axis
99       */
100     public int getAxis();
101 
102     /**
103      * Get an Iterator for the current axis starting in the given contextNode.
104      * 
105      * @param contextNode the node from which to follow this step
106      * @param support the remaining context for the traversal
107      * @return an iterator over the nodes along the axis
108      * @throws UnsupportedAxisException if the navigator does not support this step's axis
109      * 
110      */
111     Iterator axisIterator(Object contextNode,
112                           ContextSupport support) throws UnsupportedAxisException;
113     
114 
115     /**
116      * For each node in the given context calls matches() for every node on the
117      * axis, then filters the result by each of the predicates.
118      * 
119      * @return a list of matching nodes
120      */
121     List evaluate(Context context) throws JaxenException;
122 
123 }
124