org.aspectj/bcel-builder/src/org/aspectj/apache/bcel/classfile/Attribute.java

package org.aspectj.apache.bcel.classfile;

/* ====================================================================
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 * modification, are permitted provided that the following conditions
 * are met:
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 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
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 * This software consists of voluntary contributions made by many
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 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
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import org.aspectj.apache.bcel.Constants;
import org.aspectj.apache.bcel.classfile.annotation.RuntimeInvisibleAnnotations;
import org.aspectj.apache.bcel.classfile.annotation.RuntimeInvisibleParameterAnnotations;
import org.aspectj.apache.bcel.classfile.annotation.RuntimeVisibleAnnotations;
import org.aspectj.apache.bcel.classfile.annotation.RuntimeVisibleParameterAnnotations;

import java.io.*;

/**
 * Abstract super class for <em>Attribute</em> objects. Currently the
 * <em>ConstantValue</em>, <em>SourceFile</em>, <em>Code</em>,
 * <em>Exceptiontable</em>, <em>LineNumberTable</em>, 
 * <em>LocalVariableTable</em>, <em>InnerClasses</em> and
 * <em>Synthetic</em> attributes are supported. The
 * <em>Unknown</em> attribute stands for non-standard-attributes.
 *
 * @version $Id: Attribute.java,v 1.3 2008/05/28 23:53:01 aclement Exp $
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 * @see     ConstantValue
 * @see     SourceFile
 * @see     Code
 * @see     Unknown
 * @see     ExceptionTable
 * @see     LineNumberTable
 * @see     LocalVariableTable 
 * @see     InnerClasses
 * @see     Synthetic
 * @see     Deprecated
 * @see     Signature
*/
public abstract class Attribute implements Cloneable, Node, Serializable {
	public static Attribute[] NoAttributes = new Attribute[0];

	
	protected byte         tag;       // Tag to distinguish subclasses
	protected int          nameIndex; // Points to attribute name in constant pool
	protected int          length;    // Content length of attribute field
	protected ConstantPool constantPool;
  
	
    protected Attribute(byte tag, int nameIndex, int length, ConstantPool constantPool) {
      this.tag           = tag;
      this.nameIndex     = nameIndex;
      this.length        = length;
      this.constantPool  = constantPool;
    }

    
    /** Dump attribute to file stream in binary format */
    public void dump(DataOutputStream file) throws IOException {
      file.writeShort(nameIndex);
      file.writeInt(length);
    }


  public static final Attribute readAttribute(DataInputStream file, ConstantPool cpool) throws IOException {
    byte tag       = Constants.ATTR_UNKNOWN; // Unknown attribute
    int idx        = file.readUnsignedShort();
    String name    = cpool.getConstantUtf8(idx).getBytes();
    int len        = file.readInt();

    // Compare strings to find known attribute
    for (byte i=0; i < Constants.KNOWN_ATTRIBUTES; i++) {
      if (name.equals(Constants.ATTRIBUTE_NAMES[i])) { tag = i; break; }
    }
    switch(tag) {
    	case Constants.ATTR_UNKNOWN:		return new Unknown(idx, len, file, cpool);
    	case Constants.ATTR_CONSTANT_VALUE: return new ConstantValue(idx, len, file, cpool);
    	case Constants.ATTR_SOURCE_FILE:	return new SourceFile(idx, len, file, cpool);
    	case Constants.ATTR_CODE:	  		return new Code(idx, len, file, cpool);
    	case Constants.ATTR_EXCEPTIONS:		return new ExceptionTable(idx, len, file, cpool);
    	case Constants.ATTR_LINE_NUMBER_TABLE:    return new LineNumberTable(idx, len, file, cpool);
    	case Constants.ATTR_LOCAL_VARIABLE_TABLE: return new LocalVariableTable(idx, len, file, cpool);
    	case Constants.ATTR_INNER_CLASSES:  return new InnerClasses(idx, len, file, cpool);
    	case Constants.ATTR_SYNTHETIC:      return new Synthetic(idx, len, file, cpool);
    	case Constants.ATTR_DEPRECATED:     return new Deprecated(idx, len, file, cpool);
    	case Constants.ATTR_PMG:            return new PMGClass(idx, len, file, cpool);
    	case Constants.ATTR_SIGNATURE:      return new Signature(idx, len, file, cpool);
    	case Constants.ATTR_STACK_MAP:      return new StackMap(idx, len, file, cpool);
    	case Constants.ATTR_RUNTIME_VISIBLE_ANNOTATIONS:
    		return new RuntimeVisibleAnnotations(idx,len,file,cpool);
    	case Constants.ATTR_RUNTIME_INVISIBLE_ANNOTATIONS:
    		return new RuntimeInvisibleAnnotations(idx,len,file,cpool);
    	case Constants.ATTR_RUNTIME_VISIBLE_PARAMETER_ANNOTATIONS:
    		return new RuntimeVisibleParameterAnnotations(idx,len,file,cpool);
    	case Constants.ATTR_RUNTIME_INVISIBLE_PARAMETER_ANNOTATIONS:
    		return new RuntimeInvisibleParameterAnnotations(idx,len,file,cpool);
    	case Constants.ATTR_ANNOTATION_DEFAULT:
    		return new AnnotationDefault(idx,len,file,cpool);
    	case Constants.ATTR_LOCAL_VARIABLE_TYPE_TABLE:
    		return new LocalVariableTypeTable(idx,len,file,cpool);
    	case Constants.ATTR_ENCLOSING_METHOD:
    		return new EnclosingMethod(idx,len,file,cpool);
    	default: throw new IllegalStateException();
    } 
  }    

  public String getName() {
	  return constantPool.getConstantUtf8(nameIndex).getBytes();
  }

  public final int getLength()    { return length; }    

  public final int getNameIndex() { return nameIndex; }    
  
  public final byte  getTag()     { return tag; }    

  public final ConstantPool getConstantPool() { return constantPool; }    
  
  /**
   * Use copy() if you want to have a deep copy(), ie. with all references
   * copied correctly.
   *
   * @return shallow copy of this attribute
   */
  public Object clone() {
    Object o = null;

    try {
      o = super.clone();
    } catch(CloneNotSupportedException e) {
      e.printStackTrace(); // Never occurs
    }

    return o;
  }

  /**
   * @return deep copy of this attribute
   */
  public abstract Attribute copy(ConstantPool constant_pool);

  public String toString() {
    return Constants.ATTRIBUTE_NAMES[tag];
  }

  public abstract void accept(ClassVisitor v);    

}