content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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 org.apache.kafka.server.util;
  
  import java.util.AbstractMap;
  import java.util.AbstractSet;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  import java.util.function.Function;
  
  
  /**
   * A map which presents a lightweight view of another "underlying" map. Values in the
   * underlying map will be translated by a callback before they are returned.
   * <br>
   * This class is not internally synchronized. (Typically the underlyingMap is treated as
   * immutable.)
   */
  public final class TranslatedValueMapView<K, V, B> extends AbstractMap<K, V> {
      class TranslatedValueSetView extends AbstractSet<Entry<K, V>> {
          @Override
          public Iterator<Entry<K, V>> iterator() {
              return new TranslatedValueEntryIterator(underlyingMap.entrySet().iterator());
          }
  
          @SuppressWarnings("rawtypes")
          @Override
          public boolean contains(Object o) {
              if (!(o instanceof Entry other)) return false;
              if (!underlyingMap.containsKey(other.getKey())) return false;
              B value = underlyingMap.get(other.getKey());
              V translatedValue = valueMapping.apply(value);
              return Objects.equals(translatedValue, other.getValue());
          }
  
          @Override
          public boolean isEmpty() {
              return underlyingMap.isEmpty();
          }
  
          @Override
          public int size() {
              return underlyingMap.size();
          }
      }
  
      class TranslatedValueEntryIterator implements Iterator<Entry<K, V>> {
          private final Iterator<Entry<K, B>> underlyingIterator;
  
          TranslatedValueEntryIterator(Iterator<Entry<K, B>> underlyingIterator) {
              this.underlyingIterator = underlyingIterator;
          }
  
          @Override
          public boolean hasNext() {
              return underlyingIterator.hasNext();
          }
  
          @Override
          public Entry<K, V> next() {
              Entry<K, B> underlyingEntry = underlyingIterator.next();
              return new AbstractMap.SimpleImmutableEntry<>(underlyingEntry.getKey(),
                  valueMapping.apply(underlyingEntry.getValue()));
          }
      }
  
      private final Map<K, B> underlyingMap;
      private final Function<B, V> valueMapping;
      private final TranslatedValueSetView set;
  
      public TranslatedValueMapView(Map<K, B> underlyingMap,
                                    Function<B, V> valueMapping) {
          this.underlyingMap = underlyingMap;
          this.valueMapping = valueMapping;
          this.set = new TranslatedValueSetView();
      }
  
      @Override
      public boolean containsKey(Object key) {
          return underlyingMap.containsKey(key);
      }
  
      @Override
      public V get(Object key) {
          if (!underlyingMap.containsKey(key)) return null;
          B value = underlyingMap.get(key);
          return valueMapping.apply(value);
      }
  
      @Override
      public Set<Entry<K, V>> entrySet() {
          return set;
      }
  
      @Override
      public boolean isEmpty() {
          return underlyingMap.isEmpty();
      }
  }
  