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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.classfile.visitor;

import java.util.function.BiPredicate;
import proguard.classfile.Clazz;
import proguard.util.Counter;

/**
 * This ClassVisitor delegates to a given class visitor, and then, if the given predicate succeeds
 * with the given {@link Counter} before and after values, also to a second given class visitor.
 *
 * @author Eric Lafortune
 */
public class CounterConditionalClassVisitor implements ClassVisitor {
  private final BiPredicate predicate;
  private final Counter counter;
  private final ClassVisitor classVisitor1;
  private final ClassVisitor classVisitor2;

  /** Creates a new CounterConditionalClassVisitor. */
  public CounterConditionalClassVisitor(
      Counter counter,
      BiPredicate predicate,
      ClassVisitor classVisitor1,
      ClassVisitor classVisitor2) {
    this.counter = counter;
    this.classVisitor1 = classVisitor1;
    this.classVisitor2 = classVisitor2;
    this.predicate = predicate;
  }

  // Implementations for ClassVisitor.

  @Override
  public void visitAnyClass(Clazz clazz) {
    // Remember the original count.
    int count = counter.getCount();

    clazz.accept(classVisitor1);

    // Test the predicate with old and new counts.
    if (this.predicate.test(count, counter.getCount())) {
      clazz.accept(classVisitor2);
    }
  }

  // Useful helper predicates.

  public static boolean hasIncreased(int before, int after) {
    return before < after;
  }

  public static boolean isSame(int before, int after) {
    return before == after;
  }
}