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ProGuardCORE is a free library to read, analyze, modify, and write Java class files.

There is a newer version: 9.1.6

/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2021 Guardsquare NV
 */

package proguard.classfile.visitor;

import proguard.classfile.Clazz;
import proguard.classfile.Method;
import proguard.classfile.attribute.Attribute;
import proguard.classfile.attribute.CodeAttribute;
import proguard.classfile.attribute.LineNumberTableAttribute;
import proguard.classfile.attribute.visitor.AttributeVisitor;

/**
 * Retrieves the lineNumber for a given offset from a codeattribute.
 *
 * @author James Hamilton
 */
public class LineNumberFinder implements AttributeVisitor {
  private final int offset;
  public int lineNumber = -1; // -1 == not found

  public LineNumberFinder(int offset) {
    this.offset = offset;
  }

  @Override
  public void visitAnyAttribute(Clazz clazz, Attribute attribute) {
    // not interested in Attributes except LineNumberTableAttributes and CodeAttributes
  }

  @Override
  public void visitLineNumberTableAttribute(
      Clazz clazz,
      Method method,
      CodeAttribute codeAttribute,
      LineNumberTableAttribute lineNumberTableAttribute) {
    lineNumber = lineNumberTableAttribute.getLineNumber(offset);
  }

  @Override
  public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) {
    codeAttribute.attributesAccept(clazz, method, this);
  }
}