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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.util;

import proguard.classfile.*;

/**
 * Utility methods for working with access flags. For convenience, this class defines access levels,
 * in ascending order: {@link #PRIVATE}, {@link #PACKAGE_VISIBLE}, {@link #PROTECTED}, and {@link
 * #PUBLIC}.
 *
 * @author Eric Lafortune
 */
public class AccessUtil {
  public static final int PRIVATE = 0;
  public static final int PACKAGE_VISIBLE = 1;
  public static final int PROTECTED = 2;
  public static final int PUBLIC = 3;

  // The mask of access flags.
  private static final int ACCESS_MASK =
      AccessConstants.PUBLIC | AccessConstants.PRIVATE | AccessConstants.PROTECTED;

  /**
   * Returns the corresponding access level of the given access flags.
   *
   * @param accessFlags the internal access flags as a logical bit mask of {@link
   *     AccessConstants#PRIVATE}, {@link AccessConstants#PROTECTED}, and {@link
   *     AccessConstants#PUBLIC}.
   * @return the corresponding access level: {@link #PRIVATE}, {@link #PACKAGE_VISIBLE}, {@link
   *     #PROTECTED}, or {@link #PUBLIC}.
   */
  public static int accessLevel(int accessFlags) {
    switch (accessFlags & ACCESS_MASK) {
      case AccessConstants.PRIVATE:
        return PRIVATE;
      default:
        return PACKAGE_VISIBLE;
      case AccessConstants.PROTECTED:
        return PROTECTED;
      case AccessConstants.PUBLIC:
        return PUBLIC;
    }
  }

  /**
   * Returns the corresponding access flags of the given access level.
   *
   * @param accessLevel the access level: {@link #PRIVATE}, {@link #PACKAGE_VISIBLE}, {@link
   *     #PROTECTED}, or {@link #PUBLIC}.
   * @return the corresponding internal access flags as a logical bit mask of {@link
   *     AccessConstants#PRIVATE}, {@link AccessConstants#PROTECTED}, and {@link
   *     AccessConstants#PUBLIC}.
   */
  public static int accessFlags(int accessLevel) {
    switch (accessLevel) {
      case PRIVATE:
        return AccessConstants.PRIVATE;
      default:
        return 0;
      case PROTECTED:
        return AccessConstants.PROTECTED;
      case PUBLIC:
        return AccessConstants.PUBLIC;
    }
  }

  /**
   * Replaces the access part of the given access flags.
   *
   * @param accessFlags the internal access flags as a logical bit mask of {@link
   *     AccessConstants#PRIVATE}, {@link AccessConstants#PROTECTED}, and {@link
   *     AccessConstants#PUBLIC}.
   * @param newAccessFlags the new access flags as a logical bit mask of {@link
   *     AccessConstants#PRIVATE}, {@link AccessConstants#PROTECTED}, and {@link
   *     AccessConstants#PUBLIC}.
   * @return the modified access flags.
   */
  public static int replaceAccessFlags(int accessFlags, int newAccessFlags) {
    // A private class member should not be explicitly final.
    if (newAccessFlags == AccessConstants.PRIVATE) {
      accessFlags &= ~AccessConstants.FINAL;
    }

    return (accessFlags & ~ACCESS_MASK) | (newAccessFlags & ACCESS_MASK);
  }

  /**
   * Returns whether the given access flags match the required set and unset access flags.
   *
   * @param accessFlags the internal access flags as a logical bit mask of {@link
   *     AccessConstants#PRIVATE}, {@link AccessConstants#PROTECTED}, and {@link
   *     AccessConstants#PUBLIC}.
   * @param requiredSetAccessFlags the internal access flags that should be set, as a logical bit
   *     mask of {@link AccessConstants#PRIVATE}, {@link AccessConstants#PROTECTED}, and {@link
   *     AccessConstants#PUBLIC}.
   * @param requiredUnsetAccessFlags the internal access flags that should be unset, as a logical
   *     bit mask of {@link AccessConstants#PRIVATE}, {@link AccessConstants#PROTECTED}, and {@link
   *     AccessConstants#PUBLIC}.
   * @return whether the access flags match the requirements.
   */
  public static boolean accepted(
      int accessFlags, int requiredSetAccessFlags, int requiredUnsetAccessFlags) {
    int requiredCombinedSetAccessFlags = requiredSetAccessFlags & ~ACCESS_MASK;
    int requiredOneSetAccessFlags = requiredSetAccessFlags & ACCESS_MASK;

    return (requiredCombinedSetAccessFlags & ~accessFlags) == 0
        && (requiredUnsetAccessFlags & accessFlags) == 0
        && (requiredOneSetAccessFlags == 0 || (requiredOneSetAccessFlags & accessFlags) != 0);
  }
}