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50 package org.jaxen.util;
51
52 import java.util.Iterator;
53 import java.util.LinkedList;
54 import java.util.NoSuchElementException;
55
56 import org.jaxen.JaxenConstants;
57 import org.jaxen.Navigator;
58 import org.jaxen.UnsupportedAxisException;
59
60 /***
61 *
62 * Represents the XPath <code>preceding-sibling</code> axis.
63 * The "<code>preceding-sibling</code> axis contains all the
64 * preceding siblings of the context node; if the context node is an
65 * attribute node or namespace node, the <code>preceding-sibling</code>
66 * axis is empty."
67 *
68 * @version 1.2b12
69 *
70 */
71 public class PrecedingSiblingAxisIterator implements Iterator
72 {
73 private Object contextNode;
74 private Navigator navigator;
75
76 private Iterator siblingIter;
77 private Object nextObj;
78
79 /***
80 * Create a new <code>preceding-sibling</code> axis iterator.
81 *
82 * @param contextNode the node to start from
83 * @param navigator the object model specific navigator
84 */
85 public PrecedingSiblingAxisIterator(Object contextNode,
86 Navigator navigator) throws UnsupportedAxisException
87 {
88 this.contextNode = contextNode;
89 this.navigator = navigator;
90
91 init();
92 if ( siblingIter.hasNext() )
93 {
94 this.nextObj = siblingIter.next();
95 }
96 }
97
98 private void init() throws UnsupportedAxisException
99 {
100
101 Object parent = this.navigator.getParentNode( this.contextNode );
102
103 if ( parent != null )
104 {
105 Iterator childIter = this.navigator.getChildAxisIterator( parent );
106 LinkedList siblings = new LinkedList();
107
108 while ( childIter.hasNext() )
109 {
110 Object eachChild = childIter.next();
111 if ( eachChild.equals(this.contextNode) )
112 {
113 break;
114 }
115 siblings.addFirst( eachChild );
116 }
117
118 this.siblingIter = siblings.iterator();
119
120 }
121 else {
122 this.siblingIter = JaxenConstants.EMPTY_ITERATOR;
123 }
124
125 }
126
127 /***
128 * Returns true if there are any preceding siblings remaining; false otherwise.
129 *
130 * @return true if any preceding siblings remain; false otherwise
131 *
132 * @see java.util.Iterator#hasNext()
133 */
134 public boolean hasNext()
135 {
136 return ( this.nextObj != null );
137 }
138
139 /***
140 * Returns the next preceding sibling.
141 *
142 * @return the next preceding sibling
143 *
144 * @throws NoSuchElementException if no preceding siblings remain
145 *
146 * @see java.util.Iterator#next()
147 */
148 public Object next() throws NoSuchElementException
149 {
150 if ( ! hasNext() )
151 {
152 throw new NoSuchElementException();
153 }
154
155 Object obj = this.nextObj;
156 if ( siblingIter.hasNext() )
157 {
158 this.nextObj = siblingIter.next();
159 }
160 else {
161 this.nextObj = null;
162 }
163 return obj;
164 }
165
166 /***
167 * This operation is not supported.
168 *
169 * @throws UnsupportedOperationException
170 */
171 public void remove() throws UnsupportedOperationException
172 {
173 throw new UnsupportedOperationException();
174 }
175
176 }