Source for gnu.classpath.jdwp.value.Value

   1: /* Value.java -- base class of JDWP values
   2:    Copyright (C) 2007 Free Software Foundation
   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.classpath.jdwp.value;
  40: 
  41: import gnu.classpath.jdwp.exception.InvalidClassException;
  42: import gnu.classpath.jdwp.exception.InvalidObjectException;
  43: import gnu.classpath.jdwp.exception.InvalidTagException;
  44: import gnu.classpath.jdwp.exception.JdwpInternalErrorException;
  45: 
  46: import java.io.DataOutputStream;
  47: import java.io.IOException;
  48: import java.nio.ByteBuffer;
  49: 
  50: /**
  51:  * Superclass for all JDWP Values.
  52:  *
  53:  * @author Kyle Galloway <kgallowa@redhat.com>
  54:  */
  55: public abstract class Value
  56: {
  57:   // A Tag representing the type of this value
  58:   private byte _tag;
  59: 
  60:   /**
  61:    * Create a new value of type tag.
  62:    *
  63:    * @param tag the type of the value
  64:    */
  65:   protected Value(byte tag)
  66:   {
  67:     _tag = tag;
  68:   }
  69: 
  70:   /**
  71:    * Get the tag for this Value
  72:    *
  73:    * @return the byte tag of this Value
  74:    */
  75:   public byte getTag()
  76:   {
  77:     return _tag;
  78:   }
  79: 
  80:   /**
  81:    * Calls the dervied classes writeValue method to write its value to the
  82:    * DataOutputStream.
  83:    *
  84:    * @param os write the value here
  85:    * @throws IOException
  86:    */
  87:   public void writeUntagged(DataOutputStream os)
  88:     throws IOException
  89:   {
  90:     write(os);
  91:   }
  92: 
  93:   /**
  94:    * Will write the given object as a tagged value to the DataOutputStream.
  95:    *
  96:    * @param os write the value here
  97:    * @param obj the Object to write
  98:    * @throws IOException
  99:    */
 100:   public void writeTagged(DataOutputStream os)
 101:     throws IOException
 102:   {
 103:     os.write (_tag);
 104:     write(os);
 105:   }
 106: 
 107:   /**
 108:    * This method must write the value to the DataOutputStream in a manner
 109:    * appropriate for the type of the value.
 110:    *
 111:    * @param os DataOutputStream to write to
 112:    * @throws IOException
 113:    */
 114:   protected abstract void write(DataOutputStream os)
 115:     throws IOException;
 116: 
 117:   /**
 118:    * Returns an object representing this type
 119:    *
 120:    * @return an Object represntation of this value
 121:    */
 122:   protected abstract Object getObject();
 123: 
 124:   /**
 125:    * Get an untagged object from the ByteBuffer
 126:    *
 127:    * @param bb the ByteBuffer to extract the value from
 128:    * @param type a Class representing the type
 129:    * @return an Object from the ByteBuffer of the type of the Class parameter
 130:    * @throws JdwpInternalErrorException
 131:    * @throws InvalidObjectException
 132:    */
 133:   public static Object getUntaggedObject(ByteBuffer bb, Class type)
 134:     throws JdwpInternalErrorException, InvalidObjectException, InvalidClassException
 135:   {
 136:     Value val = ValueFactory.createFromUntagged(bb, type);
 137:     return val.getObject();
 138:   }
 139: 
 140:   /**
 141:    * Get an untagged object from the ByteBuffer
 142:    *
 143:    * @param bb the ByteBuffer to extract the value from
 144:    * @param tag a byte tag representing the type
 145:    * @return an Object from the ByteBuffer of the type of the Class parameter
 146:    * @throws JdwpInternalErrorException
 147:    * @throws InvalidObjectException
 148:    */
 149:   public static Object getTaggedObject(ByteBuffer bb)
 150:     throws JdwpInternalErrorException, InvalidObjectException, InvalidTagException
 151:   {
 152:     Value val = ValueFactory.createFromTagged(bb);
 153:     return val.getObject();
 154:   }
 155: }