http://www.aspectj.org: The AspectJ weaver introduces advices to java classes
  • Andy Clement 
package org.aspectj.apache.bcel.classfile;

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 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
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 *    notice, this list of conditions and the following disclaimer in
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 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    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.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
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 * 5. Products derived from this software may not be called "Apache",
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 * SUCH DAMAGE.
 * ====================================================================
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 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;

import org.aspectj.apache.bcel.Constants;


This class represents a stack map attribute used for preverification of Java classes for the 
Java 2 Micro Edition (J2ME). This attribute is used by the KVM and contained
within the Code attribute of a method. See CLDC specification 5.3.1.2

Author:M. Dahm
See Also:
Version:$Id: StackMap.java,v 1.6 2009/09/15 19:40:12 aclement Exp $
/**
 * This class represents a stack map attribute used for preverification of Java classes for the <a href="http://java.sun.com/j2me/">
 * Java 2 Micro Edition</a> (J2ME). This attribute is used by the <a href="http://java.sun.com/products/cldc/">KVM</a> and contained
 * within the Code attribute of a method. See CLDC specification 5.3.1.2
 * 
 * @version $Id: StackMap.java,v 1.6 2009/09/15 19:40:12 aclement Exp $
 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 * @see Code
 * @see StackMapEntry
 * @see StackMapType
 */
public final class StackMap extends Attribute {
	private int map_length;
	private StackMapEntry[] map; // Table of stack map entries

	/*
	 * @param name_index Index of name
	 * 
	 * @param length Content length in bytes
	 * 
	 * @param map Table of stack map entries
	 * 
	 * @param constant_pool Array of constants
	 */
	public StackMap(int name_index, int length, StackMapEntry[] map, ConstantPool constant_pool) {
		super(Constants.ATTR_STACK_MAP, name_index, length, constant_pool);

		setStackMap(map);
	}

	
Construct object from file stream.

Params:
  • name_index – Index of name
  • length – Content length in bytes
  • file – Input stream
  • constant_pool – Array of constants
Throws:
/**
	 * Construct object from file stream.
	 * 
	 * @param name_index Index of name
	 * @param length Content length in bytes
	 * @param file Input stream
	 * @throws IOException
	 * @param constant_pool Array of constants
	 */
	StackMap(int name_index, int length, DataInputStream file, ConstantPool constant_pool) throws IOException {
		this(name_index, length, (StackMapEntry[]) null, constant_pool);

		map_length = file.readUnsignedShort();
		map = new StackMapEntry[map_length];

		for (int i = 0; i < map_length; i++)
			map[i] = new StackMapEntry(file, constant_pool);
	}

	
Dump line number table attribute to file stream in binary format.

Params:
  • file – Output file stream
Throws:
/**
	 * Dump line number table attribute to file stream in binary format.
	 * 
	 * @param file Output file stream
	 * @throws IOException
	 */
	@Override
	public final void dump(DataOutputStream file) throws IOException {
		super.dump(file);
		file.writeShort(map_length);
		for (int i = 0; i < map_length; i++)
			map[i].dump(file);
	}

	
Returns:Array of stack map entries
/**
	 * @return Array of stack map entries
	 */
	public final StackMapEntry[] getStackMap() {
		return map;
	}

	
Params:
  • map – Array of stack map entries
/**
	 * @param map Array of stack map entries
	 */
	public final void setStackMap(StackMapEntry[] map) {
		this.map = map;

		map_length = (map == null) ? 0 : map.length;
	}

	
Returns:String representation.
/**
	 * @return String representation.
	 */
	@Override
	public final String toString() {
		StringBuffer buf = new StringBuffer("StackMap(");

		for (int i = 0; i < map_length; i++) {
			buf.append(map[i].toString());

			if (i < map_length - 1)
				buf.append(", ");
		}

		buf.append(')');

		return buf.toString();
	}

	//
	// /**
	// * @return deep copy of this attribute
	// */
	// public Attribute copy(ConstantPool constant_pool) {
	// StackMap c = (StackMap)clone();
	//
	// c.map = new StackMapEntry[map_length];
	// for(int i=0; i < map_length; i++)
	// c.map[i] = map[i].copy();
	//
	// c.cpool = constant_pool;
	// return c;
	// }

	
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.

Params:
  • v – Visitor object
/**
	 * 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
	 */
	@Override
	public void accept(ClassVisitor v) {
		v.visitStackMap(this);
	}

	public final int getMapLength() {
		return map_length;
	}
}