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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.editor;

import proguard.classfile.ProgramClass;
import proguard.util.ArrayUtil;

/**
 * This class can add and delete interfaces to and from classes. References to the constant pool
 * must be filled out beforehand.
 *
 * @author Eric Lafortune
 */
public class InterfacesEditor {
  private final ProgramClass targetClass;

  /** Creates a new InterfacesEditor that will edit interfaces in the given target class. */
  public InterfacesEditor(ProgramClass targetClass) {
    this.targetClass = targetClass;
  }

  /** Adds the specified interface to the target class, if it isn't present yet. */
  public void addInterface(int interfaceConstantIndex) {
    // Is the interface not yet present?
    if (findInterfaceIndex(interfaceConstantIndex) < 0) {
      // Append the interface.
      targetClass.u2interfaces =
          ArrayUtil.add(
              targetClass.u2interfaces, targetClass.u2interfacesCount++, interfaceConstantIndex);
    }
  }

  /** Deletes the given interface from the target class, if it is present. */
  public void deleteInterface(int interfaceConstantIndex) {
    // Is the interface already present?
    int interfaceIndex = findInterfaceIndex(interfaceConstantIndex);
    if (interfaceIndex >= 0) {
      int interfacesCount = --targetClass.u2interfacesCount;
      int[] interfaces = targetClass.u2interfaces;

      // Shift the other interfaces in the array.
      for (int index = interfaceIndex; index < interfacesCount; index++) {
        interfaces[index] = interfaces[index + 1];
      }

      // Clear the remaining entry in the array.
      interfaces[interfacesCount] = 0;
    }
  }

  // Small utility methods.

  /** Finds the index of the specified interface in the list of interfaces of the target class. */
  private int findInterfaceIndex(int interfaceConstantIndex) {
    int interfacesCount = targetClass.u2interfacesCount;
    int[] interfaces = targetClass.u2interfaces;

    for (int index = 0; index < interfacesCount; index++) {
      if (interfaces[index] == interfaceConstantIndex) {
        return index;
      }
    }

    return -1;
  }
}