Java example source code file (DescendingVisitor.java)

This example Java source code file (DescendingVisitor.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

attribute, codeexception, constant, descendingvisitor, field, innerclass, javaclass, linenumber, localvariable, method, object, stack, stackmapentry, util, visitor

The DescendingVisitor.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
package com.sun.org.apache.bcel.internal.classfile;

/* ====================================================================
 * 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,
 * 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 java.util.Stack;

/**
 * Traverses a JavaClass with another Visitor object 'piggy-backed'
 * that is applied to all components of a JavaClass object. I.e. this
 * class supplies the traversal strategy, other classes can make use
 * of it.
 *
 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm
 */
public class DescendingVisitor implements Visitor {
  private JavaClass clazz;
  private Visitor   visitor;
  private Stack     stack = new Stack();

  /** @return container of current entitity, i.e., predecessor during traversal
   */
  public Object predecessor() {
    return predecessor(0);
  }

  /**
   * @param level nesting level, i.e., 0 returns the direct predecessor
   * @return container of current entitity, i.e., predecessor during traversal
   */
  public Object predecessor(int level) {
    int size = stack.size();

    if((size < 2) || (level < 0))
      return null;
    else
      return stack.elementAt(size - (level + 2)); // size - 1 == current
  }

  /** @return current object
   */
  public Object current() {
    return stack.peek();
  }

  /**
   * @param clazz Class to traverse
   * @param visitor visitor object to apply to all components
   */
  public DescendingVisitor(JavaClass clazz, Visitor visitor) {
    this.clazz   = clazz;
    this.visitor = visitor;
  }

  /**
   * Start traversal.
   */
  public void visit() { clazz.accept(this); }

  public void visitJavaClass(JavaClass clazz) {
    stack.push(clazz);
    clazz.accept(visitor);

    Field[] fields = clazz.getFields();
    for(int i=0; i < fields.length; i++)
      fields[i].accept(this);

    Method[] methods = clazz.getMethods();
    for(int i=0; i < methods.length; i++)
      methods[i].accept(this);

    Attribute[] attributes = clazz.getAttributes();
    for(int i=0; i < attributes.length; i++)
      attributes[i].accept(this);

    clazz.getConstantPool().accept(this);
    stack.pop();
  }

  public void visitField(Field field) {
    stack.push(field);
    field.accept(visitor);

    Attribute[] attributes = field.getAttributes();
    for(int i=0; i < attributes.length; i++)
      attributes[i].accept(this);
    stack.pop();
  }

  public void visitConstantValue(ConstantValue cv) {
    stack.push(cv);
    cv.accept(visitor);
    stack.pop();
  }

  public void visitMethod(Method method) {
    stack.push(method);
    method.accept(visitor);

    Attribute[] attributes = method.getAttributes();
    for(int i=0; i < attributes.length; i++)
      attributes[i].accept(this);

    stack.pop();
  }

  public void visitExceptionTable(ExceptionTable table) {
    stack.push(table);
    table.accept(visitor);
    stack.pop();
  }

  public void visitCode(Code code) {
    stack.push(code);
    code.accept(visitor);

    CodeException[] table = code.getExceptionTable();
    for(int i=0; i < table.length; i++)
      table[i].accept(this);

    Attribute[] attributes = code.getAttributes();
    for(int i=0; i < attributes.length; i++)
      attributes[i].accept(this);
    stack.pop();
  }

  public void visitCodeException(CodeException ce) {
    stack.push(ce);
    ce.accept(visitor);
    stack.pop();
  }

  public void visitLineNumberTable(LineNumberTable table) {
    stack.push(table);
    table.accept(visitor);

    LineNumber[] numbers = table.getLineNumberTable();
    for(int i=0; i < numbers.length; i++)
      numbers[i].accept(this);
    stack.pop();
  }

  public void visitLineNumber(LineNumber number) {
    stack.push(number);
    number.accept(visitor);
    stack.pop();
  }

  public void visitLocalVariableTable(LocalVariableTable table) {
    stack.push(table);
    table.accept(visitor);

    LocalVariable[] vars = table.getLocalVariableTable();
    for(int i=0; i < vars.length; i++)
      vars[i].accept(this);
    stack.pop();
  }

  public void visitLocalVariableTypeTable(LocalVariableTypeTable obj) {
    stack.push(obj);
    obj.accept(visitor);
    stack.pop();
  }

  public void visitStackMap(StackMap table) {
    stack.push(table);
    table.accept(visitor);

    StackMapEntry[] vars = table.getStackMap();

    for(int i=0; i < vars.length; i++)
      vars[i].accept(this);
    stack.pop();
  }

  public void visitStackMapEntry(StackMapEntry var) {
    stack.push(var);
    var.accept(visitor);
    stack.pop();
  }

  public void visitLocalVariable(LocalVariable var) {
    stack.push(var);
    var.accept(visitor);
    stack.pop();
  }

  public void visitConstantPool(ConstantPool cp) {
    stack.push(cp);
    cp.accept(visitor);

    Constant[] constants = cp.getConstantPool();
    for(int i=1; i < constants.length; i++) {
      if(constants[i] != null)
        constants[i].accept(this);
    }

    stack.pop();
  }

  public void visitConstantClass(ConstantClass constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitConstantDouble(ConstantDouble constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitConstantFieldref(ConstantFieldref constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitConstantFloat(ConstantFloat constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
 }

  public void visitConstantInteger(ConstantInteger constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitConstantInterfaceMethodref(ConstantInterfaceMethodref constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitConstantLong(ConstantLong constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitConstantMethodref(ConstantMethodref constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitConstantNameAndType(ConstantNameAndType constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitConstantString(ConstantString constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitConstantUtf8(ConstantUtf8 constant) {
    stack.push(constant);
    constant.accept(visitor);
    stack.pop();
  }

  public void visitInnerClasses(InnerClasses ic) {
    stack.push(ic);
    ic.accept(visitor);

    InnerClass[] ics = ic.getInnerClasses();
    for(int i=0; i < ics.length; i++)
      ics[i].accept(this);
    stack.pop();
  }

  public void visitInnerClass(InnerClass inner) {
    stack.push(inner);
    inner.accept(visitor);
    stack.pop();
  }

  public void visitDeprecated(Deprecated attribute) {
    stack.push(attribute);
    attribute.accept(visitor);
    stack.pop();
  }

  public void visitSignature(Signature attribute) {
    stack.push(attribute);
    attribute.accept(visitor);
    stack.pop();
  }

  public void visitSourceFile(SourceFile attribute) {
    stack.push(attribute);
    attribute.accept(visitor);
    stack.pop();
  }

  public void visitSynthetic(Synthetic attribute) {
    stack.push(attribute);
    attribute.accept(visitor);
    stack.pop();
  }

  public void visitUnknown(Unknown attribute) {
    stack.push(attribute);
    attribute.accept(visitor);
    stack.pop();
 }
}