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/*
 * All content copyright Terracotta, Inc., unless otherwise indicated.
 *
 * 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 org.terracotta.statistics;

import java.util.HashMap;
import java.util.Map;

/**
 *
 * @author cdennis
 */
public class ConstantValueStatistic implements ValueStatistic {

  private static final Map> common = new HashMap>();
  static {
    common.put(Integer.valueOf(0), new ConstantValueStatistic(0));
    common.put(Long.valueOf(0L), new ConstantValueStatistic(0L));
    common.put(null, new ConstantValueStatistic(null));
  }
  
  public static  ValueStatistic instance(T value) {
    ValueStatistic interned = (ValueStatistic) common.get(value);
    if (interned == null) {
      return new ConstantValueStatistic(value);
    } else {
      return interned;
    }
  }
  
  private final T value;
  
  private ConstantValueStatistic(T value) {
    this.value = value;
  }
  
  @Override
  public T value() {
    return value;
  }
}