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A reactive Java web server.

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/*
 * Copyright (c) 1998-2015 Caucho Technology -- all rights reserved
 *
 * This file is part of Baratine(TM)(TM)
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Baratine is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Baratine is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Baratine; if not, write to the
 *
 *   Free Software Foundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.v5.util;

import java.util.function.Supplier;

/**
 * holder for a changing value, like for a builder.
 */
public class Holder implements Supplier
{
  private Supplier _supplier;
  private T _value;
  
  public Holder(Supplier supplier)
  {
    _supplier = supplier;
  }
  
  @Override
  public T get()
  {
    Supplier supplier = _supplier;
    
    if (supplier != null) {
      return supplier.get();
    }
    else {
      return _value;
    }
  }
  
  public void close()
  {
    Supplier supplier = _supplier;
    _supplier = null;
    
    if (supplier != null) {
      _value = supplier.get();
    }
    
  }
}