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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

/*
 * ProGuardCORE -- library to process Java bytecode.
 *
 * Copyright (c) 2002-2020 Guardsquare NV
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package proguard.classfile.constant.visitor;

import proguard.classfile.Clazz;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.visitor.*;
import proguard.classfile.constant.*;

/**
 * This {@link ConstantVisitor} and {@link BootstrapMethodInfoVisitor} travels from any invoke
 * dynamic constants or bootstrap method info entries that it visits to their bootstrap method
 * handle constants, and applies a given constant visitor.
 *
 * @author Eric Lafortune
 */
public class BootstrapMethodHandleTraveler
    implements ConstantVisitor, AttributeVisitor, BootstrapMethodInfoVisitor {
  private ConstantVisitor bootstrapMethodHandleVisitor;

  // Field serving as a method argument.
  int bootstrapMethodAttributeIndex;

  /**
   * Creates a new BootstrapMethodHandleVisitor that will delegate to the given constant visitor.
   */
  public BootstrapMethodHandleTraveler(ConstantVisitor bootstrapMethodHandleVisitor) {
    this.bootstrapMethodHandleVisitor = bootstrapMethodHandleVisitor;
  }

  // Implementations for ConstantVisitor.

  public void visitAnyConstant(Clazz clazz, Constant constant) {}

  public void visitDynamicConstant(Clazz clazz, DynamicConstant dynamicConstant) {
    // Pass the method index.
    bootstrapMethodAttributeIndex = dynamicConstant.u2bootstrapMethodAttributeIndex;

    // Delegate to the bootstrap method.
    clazz.attributesAccept(this);
  }

  public void visitInvokeDynamicConstant(Clazz clazz, InvokeDynamicConstant invokeDynamicConstant) {
    // Pass the method index.
    bootstrapMethodAttributeIndex = invokeDynamicConstant.u2bootstrapMethodAttributeIndex;

    // Delegate to the bootstrap method.
    clazz.attributesAccept(this);
  }

  // Implementations for AttributeVisitor.

  public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}

  public void visitBootstrapMethodsAttribute(
      Clazz clazz, BootstrapMethodsAttribute bootstrapMethodsAttribute) {
    // Check bootstrap methods.
    bootstrapMethodsAttribute.bootstrapMethodEntryAccept(
        clazz, bootstrapMethodAttributeIndex, this);
  }

  // Implementations for BootstrapMethodInfoVisitor.

  public void visitBootstrapMethodInfo(Clazz clazz, BootstrapMethodInfo bootstrapMethodInfo) {
    // Check bootstrap method.
    clazz.constantPoolEntryAccept(
        bootstrapMethodInfo.u2methodHandleIndex, bootstrapMethodHandleVisitor);
  }
}