1 /*
   2  * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.corba.se.impl.ior ;
  27 
  28 import java.util.Collection ;
  29 import java.util.List ;
  30 import java.util.AbstractList ;
  31 import java.util.ListIterator ;
  32 import java.util.Iterator ;
  33 
  34 import com.sun.corba.se.spi.ior.MakeImmutable ;
  35 
  36 /** Simple class that delegates all List operations to
  37 * another list.  It also can be frozen, which means that
  38 * a number of operations can be performed on the list,
  39 * and then the list can be made immutable, so that no
  40 * further changes are possible.  A FreezableList is frozen
  41 * using the makeImmutable method.
  42 */
  43 public class FreezableList extends AbstractList {
  44     private List delegate = null ;
  45     private boolean immutable = false ;
  46 
  47     public boolean equals( Object obj )
  48     {
  49         if (obj == null)
  50             return false ;
  51 
  52         if (!(obj instanceof FreezableList))
  53             return false ;
  54 
  55         FreezableList other = (FreezableList)obj ;
  56 
  57         return delegate.equals( other.delegate ) &&
  58             (immutable == other.immutable) ;
  59     }
  60 
  61     public int hashCode()
  62     {
  63         return delegate.hashCode() ;
  64     }
  65 
  66     public FreezableList( List delegate, boolean immutable  )
  67     {
  68         this.delegate = delegate ;
  69         this.immutable = immutable ;
  70     }
  71 
  72     public FreezableList( List delegate )
  73     {
  74         this( delegate, false ) ;
  75     }
  76 
  77     public void makeImmutable()
  78     {
  79         immutable = true ;
  80     }
  81 
  82     public boolean isImmutable()
  83     {
  84         return immutable ;
  85     }
  86 
  87     public void makeElementsImmutable()
  88     {
  89         Iterator iter = iterator() ;
  90         while (iter.hasNext()) {
  91             Object obj = iter.next() ;
  92             if (obj instanceof MakeImmutable) {
  93                 MakeImmutable element = (MakeImmutable)obj ;
  94                 element.makeImmutable() ;
  95             }
  96         }
  97     }
  98 
  99     // Methods overridden from AbstractList
 100 
 101     public int size()
 102     {
 103         return delegate.size() ;
 104     }
 105 
 106     public Object get(int index)
 107     {
 108         return delegate.get(index) ;
 109     }
 110 
 111     public Object set(int index, Object element)
 112     {
 113         if (immutable)
 114             throw new UnsupportedOperationException() ;
 115 
 116         return delegate.set(index, element) ;
 117     }
 118 
 119     public void add(int index, Object element)
 120     {
 121         if (immutable)
 122             throw new UnsupportedOperationException() ;
 123 
 124         delegate.add(index, element) ;
 125     }
 126 
 127     public Object remove(int index)
 128     {
 129         if (immutable)
 130             throw new UnsupportedOperationException() ;
 131 
 132         return delegate.remove(index) ;
 133     }
 134 
 135     // We also override subList so that the result is a FreezableList.
 136     public List subList(int fromIndex, int toIndex)
 137     {
 138         List list = delegate.subList(fromIndex, toIndex) ;
 139         List result = new FreezableList( list, immutable ) ;
 140         return result ;
 141     }
 142 }