/*
* reserved comment block
* DO NOT REMOVE OR ALTER!
*/
package com.sun.org.apache.bcel.internal.classfile;
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* individuals on behalf of the Apache Software Foundation. For more
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import com.sun.org.apache.bcel.internal.Constants;
import java.io.*;
import java.util.HashMap;
/**
* 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 1.1.2.1 2005/07/31 23:46:25 jeffsuttor 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 {
protected int name_index; // Points to attribute name in constant pool
protected int length; // Content length of attribute field
protected byte tag; // Tag to distiguish subclasses
protected ConstantPool constant_pool;
protected Attribute(byte tag, int name_index, int length,
ConstantPool constant_pool) {
this.tag = tag;
this.name_index = name_index;
this.length = length;
this.constant_pool = constant_pool;
}
/**
* Called by objects that are traversing the nodes of the tree implicitely
* defined by the contents of a Java class. I.e., the hierarchy of methods,
* fields, attributes, etc. spawns a tree of objects.
*
* @param v Visitor object
*/
public abstract void accept(Visitor v);
/**
* Dump attribute to file stream in binary format.
*
* @param file Output file stream
* @throws IOException
*/
public void dump(DataOutputStream file) throws IOException
{
file.writeShort(name_index);
file.writeInt(length);
}
private static HashMap readers = new HashMap();
/** Add an Attribute reader capable of parsing (user-defined) attributes
* named "name". You should not add readers for the standard attributes
* such as "LineNumberTable", because those are handled internally.
*
* @param name the name of the attribute as stored in the class file
* @param r the reader object
*/
public static void addAttributeReader(String name, AttributeReader r) {
readers.put(name, r);
}
/** Remove attribute reader
*
* @param name the name of the attribute as stored in the class file
*/
public static void removeAttributeReader(String name) {
readers.remove(name);
}
/* Class method reads one attribute from the input data stream.
* This method must not be accessible from the outside. It is
* called by the Field and Method constructor methods.
*
* @see Field
* @see Method
* @param file Input stream
* @param constant_pool Array of constants
* @return Attribute
* @throws IOException
* @throws ClassFormatException
*/
public static final Attribute readAttribute(DataInputStream file,
ConstantPool constant_pool)
throws IOException, ClassFormatException
{
ConstantUtf8 c;
String name;
int name_index;
int length;
byte tag = Constants.ATTR_UNKNOWN; // Unknown attribute
// Get class name from constant pool via `name_index' indirection
name_index = (int)file.readUnsignedShort();
c = (ConstantUtf8)constant_pool.getConstant(name_index,
Constants.CONSTANT_Utf8);
name = c.getBytes();
// Length of data in bytes
length = 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; // found!
break;
}
}
// Call proper constructor, depending on `tag'
switch(tag) {
case Constants.ATTR_UNKNOWN:
AttributeReader r = (AttributeReader)readers.get(name);
if(r != null)
return r.createAttribute(name_index, length, file, constant_pool);
else
return new Unknown(name_index, length, file, constant_pool);
case Constants.ATTR_CONSTANT_VALUE:
return new ConstantValue(name_index, length, file, constant_pool);
case Constants.ATTR_SOURCE_FILE:
return new SourceFile(name_index, length, file, constant_pool);
case Constants.ATTR_CODE:
return new Code(name_index, length, file, constant_pool);
case Constants.ATTR_EXCEPTIONS:
return new ExceptionTable(name_index, length, file, constant_pool);
case Constants.ATTR_LINE_NUMBER_TABLE:
return new LineNumberTable(name_index, length, file, constant_pool);
case Constants.ATTR_LOCAL_VARIABLE_TABLE:
return new LocalVariableTable(name_index, length, file, constant_pool);
case Constants.ATTR_INNER_CLASSES:
return new InnerClasses(name_index, length, file, constant_pool);
case Constants.ATTR_SYNTHETIC:
return new Synthetic(name_index, length, file, constant_pool);
case Constants.ATTR_DEPRECATED:
return new Deprecated(name_index, length, file, constant_pool);
case Constants.ATTR_PMG:
return new PMGClass(name_index, length, file, constant_pool);
case Constants.ATTR_SIGNATURE:
return new Signature(name_index, length, file, constant_pool);
case Constants.ATTR_STACK_MAP:
return new StackMap(name_index, length, file, constant_pool);
default: // Never reached
throw new IllegalStateException("Ooops! default case reached.");
}
}
/**
* @return Length of attribute field in bytes.
*/
public final int getLength() { return length; }
/**
* @param Attribute length in bytes.
*/
public final void setLength(int length) {
this.length = length;
}
/**
* @param name_index of attribute.
*/
public final void setNameIndex(int name_index) {
this.name_index = name_index;
}
/**
* @return Name index in constant pool of attribute name.
*/
public final int getNameIndex() { return name_index; }
/**
* @return Tag of attribute, i.e., its type. Value may not be altered, thus
* there is no setTag() method.
*/
public final byte getTag() { return tag; }
/**
* @return Constant pool used by this object.
* @see ConstantPool
*/
public final ConstantPool getConstantPool() { return constant_pool; }
/**
* @param constant_pool Constant pool to be used for this object.
* @see ConstantPool
*/
public final void setConstantPool(ConstantPool constant_pool) {
this.constant_pool = constant_pool;
}
/**
* Use copy() if you want to have a deep copy(), i.e., 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);
/**
* @return attribute name.
*/
public String toString() {
return Constants.ATTRIBUTE_NAMES[tag];
}
}