1. package com.sun.org.apache.bcel.internal.classfile;

  2. 

  3. /* ====================================================================

  4.  * The Apache Software License, Version 1.1

  5.  *

  6.  * Copyright (c) 2001 The Apache Software Foundation.  All rights

  7.  * reserved.

  8.  *

  9.  * Redistribution and use in source and binary forms, with or without

  10.  * modification, are permitted provided that the following conditions

  11.  * are met:

  12.  *

  13.  * 1. Redistributions of source code must retain the above copyright

  14.  *    notice, this list of conditions and the following disclaimer.

  15.  *

  16.  * 2. Redistributions in binary form must reproduce the above copyright

  17.  *    notice, this list of conditions and the following disclaimer in

  18.  *    the documentation and/or other materials provided with the

  19.  *    distribution.

  20.  *

  21.  * 3. The end-user documentation included with the redistribution,

  22.  *    if any, must include the following acknowledgment:

  23.  *       "This product includes software developed by the

  24.  *        Apache Software Foundation (http://www.apache.org/)."

  25.  *    Alternately, this acknowledgment may appear in the software itself,

  26.  *    if and wherever such third-party acknowledgments normally appear.

  27.  *

  28.  * 4. The names "Apache" and "Apache Software Foundation" and

  29.  *    "Apache BCEL" must not be used to endorse or promote products

  30.  *    derived from this software without prior written permission. For

  31.  *    written permission, please contact apache@apache.org.

  32.  *

  33.  * 5. Products derived from this software may not be called "Apache",

  34.  *    "Apache BCEL", nor may "Apache" appear in their name, without

  35.  *    prior written permission of the Apache Software Foundation.

  36.  *

  37.  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED

  38.  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

  39.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

  40.  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR

  41.  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

  42.  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

  43.  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

  44.  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

  45.  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

  46.  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT

  47.  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

  48.  * SUCH DAMAGE.

  49.  * ====================================================================

  50.  *

  51.  * This software consists of voluntary contributions made by many

  52.  * individuals on behalf of the Apache Software Foundation.  For more

  53.  * information on the Apache Software Foundation, please see

  54.  * <http://www.apache.org/>.

  55.  */

  56. 

  57. import  com.sun.org.apache.bcel.internal.Constants;

  58. import  java.io.*;

  59. 

  60. /**

  61.  * Abstract super class for <em>Attribute</em> objects. Currently the

  62.  * <em>ConstantValue</em>, <em>SourceFile</em>, <em>Code</em>,

  63.  * <em>Exceptiontable</em>, <em>LineNumberTable</em>, 

  64.  * <em>LocalVariableTable</em>, <em>InnerClasses</em> and

  65.  * <em>Synthetic</em> attributes are supported. The

  66.  * <em>Unknown</em> attribute stands for non-standard-attributes.

  67.  *

  68.  * @version $Id: Attribute.java,v 1.1.1.1 2001/10/29 19:59:57 jvanzyl Exp $

  69.  * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>

  70.  * @see     ConstantValue

  71.  * @see     SourceFile

  72.  * @see     Code

  73.  * @see     Unknown

  74.  * @see     ExceptionTable

  75.  * @see     LineNumberTable

  76.  * @see     LocalVariableTable 

  77.  * @see     InnerClasses

  78.  * @see     Synthetic

  79.  * @see     Deprecated

  80. */

  81. public abstract class Attribute implements Cloneable, Node {

  82.   protected int          name_index; // Points to attribute name in constant pool

  83.   protected int          length;     // Content length of attribute field

  84.   protected byte         tag;        // Tag to distiguish subclasses

  85.   protected ConstantPool constant_pool;

  86. 

  87.   Attribute(byte tag, int name_index, int length, ConstantPool constant_pool) {

  88.     this.tag           = tag;

  89.     this.name_index    = name_index;

  90.     this.length        = length;

  91.     this.constant_pool = constant_pool;

  92.   }

  93. 

  94.   /**

  95.    * Called by objects that are traversing the nodes of the tree implicitely

  96.    * defined by the contents of a Java class. I.e., the hierarchy of methods,

  97.    * fields, attributes, etc. spawns a tree of objects.

  98.    *

  99.    * @param v Visitor object

  100.    */

  101.   public abstract void accept(Visitor v);    

  102. 

  103.   /**

  104.    * Dump attribute to file stream in binary format.

  105.    *

  106.    * @param file Output file stream

  107.    * @throw IOException

  108.    */

  109.   public void dump(DataOutputStream file) throws IOException

  110.   {

  111.     file.writeShort(name_index);

  112.     file.writeInt(length);

  113.   }    

  114. 

  115.   /* Class method reads one attribute from the input data stream.

  116.    * This method must not be accessible from the outside.  It is

  117.    * called by the Field and Method constructor methods.

  118.    *

  119.    * @see    Field

  120.    * @see    Method

  121.    * @param  file Input stream

  122.    * @param  constant_pool Array of constants

  123.    * @return Attribute

  124.    * @throw  IOException

  125.    * @throw  ClassFormatError

  126.    * @throw InternalError

  127.    */

  128.   static final Attribute readAttribute(DataInputStream file,

  129. 				       ConstantPool constant_pool)

  130.     throws IOException, ClassFormatError, InternalError

  131.   {

  132.     ConstantUtf8 c;

  133.     String       name;

  134.     int          name_index;

  135.     int          length;

  136.     byte         tag = Constants.ATTR_UNKNOWN; // Unknown attribute

  137. 

  138.     // Get class name from constant pool via `name_index' indirection

  139.     name_index = (int)(file.readUnsignedShort());

  140.     c          = (ConstantUtf8)constant_pool.getConstant(name_index, 

  141. 							 Constants.CONSTANT_Utf8);

  142.     name       = c.getBytes();

  143. 

  144.     // Length of data in bytes

  145.     length = file.readInt();

  146. 

  147.     // Compare strings to find known attribute

  148.     for(byte i=0; i < Constants.KNOWN_ATTRIBUTES; i++) {

  149.       if(name.equals(Constants.ATTRIBUTE_NAMES[i])) {

  150. 	tag = i; // found!

  151. 	break;

  152.       }

  153.     }

  154. 

  155.     // Call proper constructor, depending on `tag'

  156.     switch(tag) {

  157.     case Constants.ATTR_UNKNOWN:

  158.       return new Unknown(name_index, length, file, constant_pool);

  159. 

  160.     case Constants.ATTR_CONSTANT_VALUE:

  161.       return new ConstantValue(name_index, length, file, constant_pool);

  162. 

  163.     case Constants.ATTR_SOURCE_FILE:

  164.       return new SourceFile(name_index, length, file, constant_pool);

  165. 	  

  166.     case Constants.ATTR_CODE:

  167.       return new Code(name_index, length, file, constant_pool);

  168. 	  

  169.     case Constants.ATTR_EXCEPTIONS:

  170.       return new ExceptionTable(name_index, length, file, constant_pool);

  171. 	  

  172.     case Constants.ATTR_LINE_NUMBER_TABLE:

  173.       return new LineNumberTable(name_index, length, file, constant_pool);

  174. 	  

  175.     case Constants.ATTR_LOCAL_VARIABLE_TABLE:

  176.       return new LocalVariableTable(name_index, length, file, constant_pool);

  177. 

  178.     case Constants.ATTR_INNER_CLASSES:

  179.       return new InnerClasses(name_index, length, file, constant_pool);

  180. 

  181.     case Constants.ATTR_SYNTHETIC:

  182.       return new Synthetic(name_index, length, file, constant_pool);

  183. 

  184.     case Constants.ATTR_DEPRECATED:

  185.       return new Deprecated(name_index, length, file, constant_pool);

  186. 

  187.     case Constants.ATTR_PMG:

  188.       return new PMGClass(name_index, length, file, constant_pool);

  189. 

  190.     case Constants.ATTR_SIGNATURE:

  191.       return new Signature(name_index, length, file, constant_pool);

  192. 

  193.     case Constants.ATTR_STACK_MAP:

  194.       return new StackMap(name_index, length, file, constant_pool);

  195. 

  196.     default: // Never reached

  197.       throw new InternalError("Ooops! default case reached.");

  198.     }

  199.   }    

  200. 

  201.   /**

  202.    * @return Length of attribute field in bytes.

  203.    */  

  204.   public final int   getLength()    { return length; }    

  205. 

  206.   /**

  207.    * @param Attribute length in bytes.

  208.    */

  209.   public final void setLength(int length) {

  210.     this.length = length;

  211.   }    

  212. 

  213.   /**

  214.    * @param name_index of attribute.

  215.    */

  216.   public final void setNameIndex(int name_index) {

  217.     this.name_index = name_index;

  218.   }    

  219. 

  220.   /**

  221.    * @return Name index in constant pool of attribute name.

  222.    */  

  223.   public final int getNameIndex() { return name_index; }    

  224. 

  225.   /**

  226.    * @return Tag of attribute, i.e., its type. Value may not be altered, thus

  227.    * there is no setTag() method.

  228.    */

  229.   public final byte  getTag()       { return tag; }    

  230. 

  231.   /**

  232.    * @return Constant pool used by this object.

  233.    * @see ConstantPool

  234.    */   

  235.   public final ConstantPool getConstantPool() { return constant_pool; }    

  236. 

  237.   /**

  238.    * @param constant_pool Constant pool to be used for this object.

  239.    * @see ConstantPool

  240.    */   

  241.   public final void setConstantPool(ConstantPool constant_pool) {

  242.     this.constant_pool = constant_pool;

  243.   }

  244.   

  245.   /**

  246.    * Use copy() if you want to have a deep copy(), i.e., with all references

  247.    * copied correctly.

  248.    *

  249.    * @return shallow copy of this attribute

  250.    */

  251.   public Object clone() {

  252.     Object o = null;

  253. 

  254.     try {

  255.       o = super.clone();

  256.     } catch(CloneNotSupportedException e) {

  257.       e.printStackTrace(); // Never occurs

  258.     }

  259. 

  260.     return o;

  261.   }

  262. 

  263.   /**

  264.    * @return deep copy of this attribute

  265.    */

  266.   public abstract Attribute copy(ConstantPool constant_pool);

  267. 

  268.   /**

  269.    * @return attribute name.

  270.    */ 

  271.   public String toString() {

  272.     return Constants.ATTRIBUTE_NAMES[tag];

  273.   }

  274. }