Package org.aspectj.apache.bcel.generic

Source Code of org.aspectj.apache.bcel.generic.LocalVariableGen

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:
*
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*    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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* 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;
    }
  }
}
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