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A continuously growing collection of utilities to measure performance, get better diagnostics, improve performance, or do things more reliably, faster that other open source libraries...

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/*
 * Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Additionally licensed with:
 *
 * 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.spf4j.base;

import javax.annotation.Nullable;

/**
 *
 * @author Zoltan Farkas
 */
public abstract class NullAbleOptional {

  public static final NullAbleOptional EMPTY = new NullAbleOptional() {
    @Override
    public Object get() {
      throw new UnsupportedOperationException("Optional is empty");
    }

    @Override
    public boolean isPresent() {
      return false;
    }
  };

  public static NullAbleOptional empty() {
    return EMPTY;
  }

  @Nullable
  public abstract T get();

  public abstract boolean isPresent();

  @Override
  public final String toString() {
    return "Optional{present = " + isPresent() + ", value=" + get() + '}';
  }

  public static  NullAbleOptional of(@Nullable final T value) {
    return new NullAbleOptional() {
      @Override
      @Nullable
      public T get() {
        return value;
      }

      @Override
      public boolean isPresent() {
        return true;
      }
    };
  }

}