// 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;

import com.android.tools.r8.graph.DexProgramClass;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;

public abstract class MultiClassSameReferencePolicy<T> extends MultiClassPolicy {

  @Override
  public final Collection<HorizontalMergeGroup> apply(HorizontalMergeGroup group) {
    Map<T, HorizontalMergeGroup> groups = new LinkedHashMap<>();
    for (DexProgramClass clazz : group) {
      T mergeKey = getMergeKey(clazz);
      if (mergeKey != null) {
        groups.computeIfAbsent(mergeKey, ignore -> new HorizontalMergeGroup()).add(clazz);
      }
    }
    removeTrivialGroups(groups.values());
    return groups.values();
  }

  public abstract T getMergeKey(DexProgramClass clazz);

  protected final T ineligibleForClassMerging() {
    return null;
  }
}