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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) 2002-2021 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.util;

import proguard.evaluation.PartialEvaluator;
import proguard.evaluation.Stack;
import proguard.evaluation.value.IdentifiedArrayReferenceValue;
import proguard.evaluation.value.IdentifiedReferenceValue;
import proguard.evaluation.value.ReferenceValue;
import proguard.evaluation.value.Value;

/** Helper functions to access PartialEvaluator results more conveniently. */
public class PartialEvaluatorUtils {

  private PartialEvaluatorUtils() {}

  /**
   * Returns the value from the stack, counting from the top of the stack. If the stack does not
   * contain that many elements, returns null.
   */
  public static Value getStackValue(Stack stack, int indexFromTop) {
    if (stack != null && stack.size() > indexFromTop) {
      return stack.getTop(indexFromTop);
    }
    return null;
  }

  /**
   * Returns the value from the before stack at offset, counting from the top. If the stack does not
   * contain that many elements, returns null.
   */
  public static Value getStackBefore(PartialEvaluator partialEvaluator, int offset, int index) {
    if (partialEvaluator.getStackBefore(offset) != null
        && partialEvaluator.getStackBefore(offset).size() > index) {
      return partialEvaluator.getStackBefore(offset).getTop(index);
    }
    return null;
  }

  /**
   * Returns the identifier of a reference value for which {@link Value#isSpecific()} is true (i.e.,
   * the reference is identified by a unique number).
   *
   * This helper method is needed because {@link IdentifiedReferenceValue} and {@link
   * IdentifiedArrayReferenceValue} do not share the relevant portion of the class hierarchy, but a
   * better solution should be implemented in the future.
   */
  public static Object getIdFromSpecificReferenceValue(ReferenceValue value) {
    if (value instanceof IdentifiedReferenceValue) {
      return ((IdentifiedReferenceValue) value).id;
    }
    if (value instanceof IdentifiedArrayReferenceValue) {
      return ((IdentifiedArrayReferenceValue) value).id;
    }
    throw new IllegalStateException("Can't extract the id from a non identified reference value");
  }
}