src/main/java/com/android/tools/r8/horizontalclassmerging/policies/NoClassAnnotationCollisions.java

// Copyright (c) 2020, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package com.android.tools.r8.horizontalclassmerging.policies;

import static com.android.tools.r8.utils.IteratorUtils.createCircularIterator;

import com.android.tools.r8.graph.DexProgramClass;
import com.android.tools.r8.horizontalclassmerging.MergeGroup;
import com.android.tools.r8.horizontalclassmerging.MultiClassPolicy;
import com.google.common.collect.ImmutableList;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

public class NoClassAnnotationCollisions extends MultiClassPolicy {

  @Override
  public Collection<MergeGroup> apply(MergeGroup group) {
    // Create a new merge group for each class that has annotations.
    List<MergeGroup> newGroups = new LinkedList<>();
    for (DexProgramClass clazz : group) {
      if (clazz.hasAnnotations()) {
        newGroups.add(new MergeGroup(clazz));
      }
    }

    // If there were at most one class with annotations, then just return the original merge group.
    if (newGroups.size() <= 1) {
      return ImmutableList.of(group);
    }

    // Otherwise, fill up the new merge groups with the classes that do not have annotations.
    Iterator<MergeGroup> newGroupsIterator = createCircularIterator(newGroups);
    for (DexProgramClass clazz : group) {
      if (!clazz.hasAnnotations()) {
        newGroupsIterator.next().add(clazz);
      }
    }
    return removeTrivialGroups(newGroups);
  }

  @Override
  public String getName() {
    return "NoClassAnnotationCollisions";
  }
}