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com.bitplan.simplegraph.core submodule of com.bitplan.simplegraph

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/**
 * Copyright (c) 2018 BITPlan GmbH
 *
 * http://www.bitplan.com
 *
 * This file is part of the Opensource project at:
 * https://github.com/BITPlan/com.bitplan.simplegraph
 *
 * 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 com.bitplan.simplegraph.core;

import java.util.List;
import java.util.Optional;

/**
 * filter for property keys
 * 
 * @author wf
 *
 */
public interface Keys {
  public static final String[] EMPTY_KEYS = {};

  public boolean hasKey(String key);

  public default boolean isEmpty() {
    if (this.getKeysList().isPresent())
      return this.getKeysList().get().size() == 0;
    else
      return true;
  }

  Optional> getKeysList();

  String[] getKeys();
}