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50 package org.jaxen.util;
51
52 import java.util.HashSet;
53 import java.util.Iterator;
54 import java.util.LinkedList;
55 import java.util.NoSuchElementException;
56 import java.util.Set;
57
58 import org.jaxen.Navigator;
59
60 /***
61 * @deprecated this iterator is no longer used to implement any of the Jaxen axes. If you have implemented
62 * a navigator-specific axis based on this class, take a look at the DescendantAxisIterator for ideas
63 * on how to remove that dependency.
64 */
65 public abstract class StackedIterator implements Iterator
66 {
67
68 private LinkedList iteratorStack;
69 private Navigator navigator;
70
71 private Set created;
72
73 public StackedIterator(Object contextNode,
74 Navigator navigator)
75 {
76 this.iteratorStack = new LinkedList();
77 this.created = new HashSet();
78
79 init( contextNode,
80 navigator );
81 }
82
83 protected StackedIterator()
84 {
85 this.iteratorStack = new LinkedList();
86 this.created = new HashSet();
87 }
88
89 protected void init(Object contextNode,
90 Navigator navigator)
91 {
92 this.navigator = navigator;
93
94
95 }
96
97 protected Iterator internalCreateIterator(Object contextNode)
98 {
99 if ( this.created.contains( contextNode ) )
100 {
101 return null;
102 }
103
104 this.created.add( contextNode );
105
106 return createIterator( contextNode );
107 }
108
109 public boolean hasNext()
110 {
111 Iterator curIter = currentIterator();
112
113 if ( curIter == null )
114 {
115 return false;
116 }
117
118 return curIter.hasNext();
119 }
120
121 public Object next() throws NoSuchElementException
122 {
123 if ( ! hasNext() )
124 {
125 throw new NoSuchElementException();
126 }
127
128 Iterator curIter = currentIterator();
129 Object object = curIter.next();
130
131 pushIterator( internalCreateIterator( object ) );
132
133 return object;
134 }
135
136 public void remove() throws UnsupportedOperationException
137 {
138 throw new UnsupportedOperationException();
139 }
140
141 abstract protected Iterator createIterator(Object contextNode);
142
143 protected void pushIterator(Iterator iter)
144 {
145 if ( iter != null )
146 {
147 this.iteratorStack.addFirst(iter);
148 }
149 }
150
151 private Iterator currentIterator()
152 {
153 while ( iteratorStack.size() > 0 )
154 {
155 Iterator curIter = (Iterator) iteratorStack.getFirst();
156
157 if ( curIter.hasNext() )
158 {
159 return curIter;
160 }
161
162 iteratorStack.removeFirst();
163 }
164
165 return null;
166 }
167
168 protected Navigator getNavigator()
169 {
170 return this.navigator;
171 }
172 }