libjava/java/nio/charset/CoderResult.java

   1 /* CoderResult.java --
   2    Copyright (C) 2002 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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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 package java.nio.charset;
  39
  40 import java.lang.ref.WeakReference;
  41 import java.nio.BufferOverflowException;
  42 import java.nio.BufferUnderflowException;
  43 import java.util.HashMap;
  44
  45 /**
  46  * @author Jesse Rosenstock
  47  * @since 1.4
  48  */
  49 public class CoderResult
  50 {
  51   private static final int TYPE_MALFORMED  = 0;
  52   private static final int TYPE_OVERFLOW   = 1;
  53   private static final int TYPE_UNDERFLOW  = 2;
  54   private static final int TYPE_UNMAPPABLE = 3;
  55
  56   public static final CoderResult OVERFLOW
  57     = new CoderResult (TYPE_OVERFLOW, 0);
  58   public static final CoderResult UNDERFLOW
  59     = new CoderResult (TYPE_UNDERFLOW, 0);
  60
  61   private static final String[] names
  62     = { "MALFORMED", "OVERFLOW", "UNDERFLOW", "UNMAPPABLE" };
  63
  64   private static final Cache malformedCache
  65     = new Cache ()
  66       {
  67         protected CoderResult make (int length)
  68         {
  69           return new CoderResult (TYPE_MALFORMED, length);
  70         }
  71       };
  72
  73   private static final Cache unmappableCache
  74     = new Cache ()
  75       {
  76         protected CoderResult make (int length)
  77         {
  78           return new CoderResult (TYPE_UNMAPPABLE, length);
  79         }
  80       };
  81
  82   private final int type;
  83   private final int length;
  84
  85   private CoderResult (int type, int length)
  86   {
  87     this.type = type;
  88     this.length = length;
  89   }
  90
  91   public boolean isError ()
  92   {
  93     return length > 0;
  94   }
  95
  96   public boolean isMalformed ()
  97   {
  98     return type == TYPE_MALFORMED;
  99   }
 100
 101   public boolean isOverflow ()
 102   {
 103     return type == TYPE_OVERFLOW;
 104   }
 105
 106   public boolean isUnderflow ()
 107   {
 108     return type == TYPE_UNDERFLOW;
 109   }
 110
 111   public boolean isUnmappable ()
 112   {
 113     return type == TYPE_UNMAPPABLE;
 114   }
 115
 116   public int length ()
 117   {
 118     if (length <= 0)
 119       throw new UnsupportedOperationException ();
 120     else
 121       return length;
 122   }
 123
 124   public static CoderResult malformedForLength (int length)
 125   {
 126     return malformedCache.get (length);
 127   }
 128
 129   public void throwException ()
 130     throws CharacterCodingException
 131   {
 132     switch (type)
 133       {
 134         case TYPE_MALFORMED:
 135           throw new MalformedInputException (length);
 136         case TYPE_OVERFLOW:
 137           throw new BufferOverflowException ();
 138         case TYPE_UNDERFLOW:
 139           throw new BufferUnderflowException ();
 140         case TYPE_UNMAPPABLE:
 141           throw new UnmappableCharacterException (length);
 142       }
 143   }
 144
 145   public String toString ()
 146   {
 147     String name = names[type];
 148     return (length > 0) ? name + '[' + length + ']' : name;
 149   }
 150
 151   public static CoderResult unmappableForLength (int length)
 152   {
 153     return unmappableCache.get (length);
 154   }
 155
 156   private abstract static class Cache
 157   {
 158     private final HashMap cache;
 159
 160     private Cache ()
 161     {
 162       // If we didn't synchronize on this, then cache would be initialized
 163       // without holding a lock.  Undefined behavior would occur if the
 164       // first thread to call get(int) was not the same as the one that
 165       // called the constructor.
 166       synchronized (this)
 167         {
 168           cache = new HashMap ();
 169         }
 170     }
 171
 172     private synchronized CoderResult get (int length)
 173     {
 174       if (length <= 0)
 175         throw new IllegalArgumentException ("Non-positive length");
 176
 177       Integer len = new Integer (length);
 178       CoderResult cr = null;
 179       Object o;
 180       if ((o = cache.get (len)) != null)
 181         cr = (CoderResult) ((WeakReference) o).get ();
 182       if (cr == null)
 183         {
 184           cr = make (length);
 185           cache.put (len, new WeakReference (cr));
 186         }
 187
 188       return cr;
 189     }
 190
 191     protected abstract CoderResult make (int length);
 192   }
 193 }