org.aspectj.weaver/source/org/aspectj/apache/bcel/generic/LocalVariableGen.java

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 (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
 *    written permission, please contact apache@apache.org.
 *
 * 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,
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 * 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
 * <http://www.apache.org/>.
 */

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