1 /* GiopNamingEnumeration.java -- handles corbaname: urls
2    Copyright (C) 2006 Free Software Foundation, Inc.
3 
4 This file is part of GNU Classpath.
5 
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
10 
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 General Public License for more details.
15 
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; see the file COPYING.  If not, write to the
18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19 02110-1301 USA.
20 
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library.  Thus, the terms and
23 conditions of the GNU General Public License cover the whole
24 combination.
25 
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module.  An independent module is a module which is not derived from
33 or based on this library.  If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so.  If you do not wish to do so, delete this
36 exception statement from your version. */
37 
38 
39 package gnu.javax.naming.giop;
40 
41 import java.util.NoSuchElementException;
42 
43 import javax.naming.NamingEnumeration;
44 import javax.naming.NamingException;
45 
46 import org.omg.CosNaming.Binding;
47 import org.omg.CosNaming.BindingIterator;
48 import org.omg.CosNaming.BindingIteratorHolder;
49 import org.omg.CosNaming.BindingListHolder;
50 
51 /**
52  * Iterates over name class pairs, obtaining values first from the binding list
53  * and then from the binding iterator.
54  *
55  * @author Audrius Meskauskas
56  */
57 public abstract class GiopNamingEnumeration implements NamingEnumeration
58 {
59   /**
60    * The array of bindings, returned at once.
61    */
62   Binding[] list;
63 
64   /**
65    * The binding iterator to obtain the subsequent bindings. May be null,
66    * if all values are stored in the <code>list</code>.
67    */
68   BindingIterator iterator;
69 
70   /**
71    * The batch size.
72    */
73   int batch;
74 
75   /**
76    * The position of the element in the binding list, that must be returned
77    * during the subsequent call of the next(). If this field is grater or equal
78    * to the lenght of the list, the subsequent values must be requested from the
79    * iterator.
80    */
81   int p;
82 
GiopNamingEnumeration(BindingListHolder bh, BindingIteratorHolder bih, int batchSize)83   GiopNamingEnumeration(BindingListHolder bh, BindingIteratorHolder bih, int batchSize)
84   {
85     list = bh.value;
86     iterator = bih.value;
87     batch = batchSize;
88   }
89 
90   /**
91    * Convert from the CORBA binding into that this enumeration should return.
92    *
93    * @param binding
94    *          the binding to convert
95    * @return the value, that must be returned by the {@link #next()}.
96    */
convert(Binding binding)97   public abstract Object convert(Binding binding);
98 
close()99   public void close() throws NamingException
100   {
101     if (iterator != null)
102       {
103         iterator.destroy();
104         iterator = null;
105       }
106   }
107 
108   /**
109    * Checks if there are more elements to return.
110    *
111    * @throws NamingException
112    *           never
113    */
hasMore()114   public boolean hasMore() throws NamingException
115   {
116     return hasMoreElements();
117   }
118 
119   /**
120    * Returns the next element.
121    *
122    * @throws NamingException
123    *           never
124    */
next()125   public Object next() throws NamingException
126   {
127     return nextElement();
128   }
129 
130   /**
131    * Checks if there are more elements to return.
132    */
hasMoreElements()133   public boolean hasMoreElements()
134   {
135     if (p < 0)
136       return false;
137     else if (p < list.length)
138       return true;
139     else
140       return getMore();
141   }
142 
143   /**
144    * Returns the next element.
145    */
nextElement()146   public Object nextElement()
147   {
148     if (p < 0)
149       throw new NoSuchElementException();
150     else if (p < list.length)
151       return convert(list[p++]);
152     else if (getMore())
153       // getMore updates p
154       return convert(list[p++]);
155     else
156       throw new NoSuchElementException();
157   }
158 
159   /**
160    * Tries to obtain more elements, return true on success. Updates the fields
161    * accordingly.
162    */
getMore()163   boolean getMore()
164   {
165     if (iterator != null)
166       {
167         BindingListHolder holder = new BindingListHolder();
168         boolean rt = iterator.next_n(batch, holder);
169         if (rt)
170           {
171             // The new pack of the bindings arrived.
172             p = 0;
173             list = holder.value;
174             return true;
175           }
176         else
177           {
178             iterator.destroy();
179             iterator = null;
180             p = -1;
181             return false;
182           }
183       }
184     else
185       return false;
186   }
187 }
188