linenumbergen.java

该开源工具主要用于class文件的操作

package org.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 [e-mail].
 *
 * 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
 * <http://www.apache.org/>.
 */

import org.apache.bcel.Constants;
import org.apache.bcel.classfile.*;

/** 
 * This class represents a line number within a method, i.e., give an instruction
 * a line number corresponding to the source code line.
 *
 * @version $Id: LineNumberGen.java,v 1.1.1.1 2001/10/29 20:00:23 jvanzyl Exp $
 * @author  <A HREF="mailto:[e-mail]">M. Dahm</A>
 * @see     LineNumber
 * @see     MethodGen
 */
public class LineNumberGen implements InstructionTargeter, Cloneable {
  private InstructionHandle ih;
  private int               src_line;

  /**
   * Create a line number.
   *
   * @param ih instruction handle to reference
   * @return new line number object
   */
  public LineNumberGen(InstructionHandle ih, int src_line) {
    setInstruction(ih);
    setSourceLine(src_line);
  }

  /**
   * @return true, if ih is target of this line number
   */
  public boolean containsTarget(InstructionHandle ih) {
    return this.ih == ih;
  }

  /**
   * @param old_ih old target
   * @param new_ih new target
   */
  public void updateTarget(InstructionHandle old_ih, InstructionHandle new_ih) {
    if(old_ih != ih)
      throw new ClassGenException("Not targeting " + old_ih + ", but " + ih + "}");
    else
      setInstruction(new_ih);
  }

  /**
   * Get LineNumber attribute .
   *
   * 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.
   */
  public LineNumber getLineNumber() {
    return new LineNumber(ih.getPosition(), src_line);
  }

  public void setInstruction(InstructionHandle ih) {
    BranchInstruction.notifyTarget(this.ih, ih, this);

    this.ih = ih;
  }

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

  public InstructionHandle getInstruction()               { return ih; }
  public void              setSourceLine(int src_line)    { this.src_line = src_line; }
  public int               getSourceLine()                { return src_line; }
}