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package org.mozc.android.inputmethod.japanese.util;

import java.util.LinkedHashMap;
import java.util.Map;

/**
 * Simple LRU cache implementation based on LinkedHashMap.
 *
 */
public class LeastRecentlyUsedCacheMap<K, V> extends LinkedHashMap<K, V> {
  private final int maxEntrySize;

  /**
   * @param maxEntrySize the number of elements this cache should hold.
   */
  public LeastRecentlyUsedCacheMap(int maxEntrySize) {
    // We don't need to resize because if the number of elements is limited.
    // Thus, set factor to 1.
    super(maxEntrySize + maxEntrySize / 2, 1f, true);
    if (maxEntrySize <= 0) {
      throw new IllegalArgumentException("maxEntrySize should be positive value: " + maxEntrySize);
    }
    this.maxEntrySize = maxEntrySize;
  }

  @Override
  protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
    return size() > maxEntrySize;
  }
}
