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/*
 * SonarQube Java
 * Copyright (C) 2012-2016 SonarSource SA
 * mailto:contact AT sonarsource DOT com
 *
 * This program 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 3 of the License, or (at your option) any later version.
 *
 * This program 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
 * Lesser 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.java.collections;

/**
 * Persistent (functional) Set.
 *
 * @author Evgeny Mandrikov
 * @param  the type of elements maintained by this set
 */
public interface PSet {

  /**
   * @return new set with added element, or this if element already in the set
   */
  PSet add(E e);

  /**
   * @return new set with removed element, or this if set does not contain given element
   */
  PSet remove(E e);

  /**
   * @return true if this set contains the specified element
   */
  boolean contains(E e);

  /**
   * Performs the given action for each entry in this set until all elements have been processed or the action throws an exception.
   */
  void forEach(Consumer action);

  /**
   * @return true if this set contains no elements
   */
  boolean isEmpty();

  /**
   * Represents an operation that accepts a single input argument and returns no result.
   *
   * This interface intended to be a functional interface as defined by the Java Language Specification.
   */
  interface Consumer {

    void accept(E e);

  }

}