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AspectJ tools most notably contains the AspectJ compiler (AJC). AJC applies aspects to Java classes during compilation, fully replacing Javac for plain Java classes and also compiling native AspectJ or annotation-based @AspectJ syntax. Furthermore, AJC can weave aspects into existing class files in a post-compile binary weaving step. This library is a superset of AspectJ weaver and hence also of AspectJ runtime.
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package org.aspectj.apache.bcel.generic;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * 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.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    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 (https://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
 *    written permission, please contact [email protected].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * 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
 * .
 */

import org.aspectj.apache.bcel.Constants;
import org.aspectj.apache.bcel.classfile.ConstantPool;
import org.aspectj.apache.bcel.classfile.LocalVariable;

/**
 * This class represents a local variable within a method. It contains its scope, name and type. The generated LocalVariable object
 * can be obtained with getLocalVariable which needs the instruction list and the constant pool as parameters.
 *
 * @version $Id: LocalVariableGen.java,v 1.7 2008/08/28 00:04:23 aclement Exp $
 * @author M. Dahm
 * @see LocalVariable
 * @see MethodGen
 */
public class LocalVariableGen implements InstructionTargeter, Cloneable, java.io.Serializable {
	private int index;
	private String name;
	private Type type;
	private InstructionHandle start, end;

	/**
	 * Generate a local variable that with index `index'. Note that double and long variables need two indexs. Index indices have to
	 * be provided by the user.
	 *
	 * @param index index of local variable
	 * @param name its name
	 * @param type its type
	 * @param start from where the instruction is valid (null means from the start)
	 * @param end until where the instruction is valid (null means to the end)
	 */
	public LocalVariableGen(int index, String name, Type type, InstructionHandle start, InstructionHandle end) {
		if (index < 0 || index > Constants.MAX_SHORT) {
			throw new ClassGenException("Invalid index index: " + index);
		}

		this.name = name;
		this.type = type;
		this.index = index;
		setStart(start);
		setEnd(end);
	}

	/**
	 * Get LocalVariable object.
	 *
	 * This relies on that the instruction list has already been dumped to byte code or or that the `setPositions' methods has been
	 * called for the instruction list.
	 *
	 * Note that for local variables whose scope end at the last instruction of the method's code, the JVM specification is
	 * ambiguous: both a start_pc+length ending at the last instruction and start_pc+length ending at first index beyond the end of
	 * the code are valid.
	 *
	 * @param il instruction list (byte code) which this variable belongs to
	 * @param cp constant pool
	 */
	public LocalVariable getLocalVariable(ConstantPool cp) {
		int start_pc = start.getPosition();
		int length = end.getPosition() - start_pc;

		if (length > 0) {
			length += end.getInstruction().getLength();
		}

		int name_index = cp.addUtf8(name);
		int signature_index = cp.addUtf8(type.getSignature());

		return new LocalVariable(start_pc, length, name_index, signature_index, index, cp);
	}

	public void setIndex(int index) {
		this.index = index;
	}

	public int getIndex() {
		return index;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getName() {
		return name;
	}

	public void setType(Type type) {
		this.type = type;
	}

	public Type getType() {
		return type;
	}

	public InstructionHandle getStart() {
		return start;
	}

	public InstructionHandle getEnd() {
		return end;
	}

	public void setStart(InstructionHandle start) {
		InstructionBranch.notifyTarget(this.start, start, this);
		this.start = start;
	}

	public void setEnd(InstructionHandle end) {
		InstructionBranch.notifyTarget(this.end, end, this);
		this.end = end;
	}

	/**
	 * @param old_ih old target, either start or end
	 * @param new_ih new target
	 */
	public void updateTarget(InstructionHandle old_ih, InstructionHandle new_ih) {
		boolean targeted = false;

		if (start == old_ih) {
			targeted = true;
			setStart(new_ih);
		}

		if (end == old_ih) {
			targeted = true;
			setEnd(new_ih);
		}

		if (!targeted) {
			throw new ClassGenException("Not targeting " + old_ih + ", but {" + start + ", " + end + "}");
		}
	}

	/**
	 * @return true, if ih is target of this variable
	 */
	public boolean containsTarget(InstructionHandle ih) {
		return start == ih || end == ih;
	}

	/**
	 * We consider to local variables to be equal, if the use the same index and are valid in the same range.
	 */
	public boolean equals(Object o) {
		if (!(o instanceof LocalVariableGen)) {
			return false;
		}

		LocalVariableGen l = (LocalVariableGen) o;
		return l.index == index && l.start == start && l.end == end;
	}

	public String toString() {
		return "LocalVariableGen(" + name + ", " + type + ", " + start + ", " + end + ")";
	}

	public Object clone() {
		try {
			return super.clone();
		} catch (CloneNotSupportedException e) {
			System.err.println(e);
			return null;
		}
	}
}