package org.djutils.immutablecollections;
   
   import java.util.Collection;
   import java.util.Set;
   import java.util.Spliterator;
   import java.util.function.Consumer;
   import java.util.stream.Stream;
   
   import org.djutils.exceptions.Throw;
  
  /**
   * An abstract base class for an immutable wrapper for a Set.
   * <p>
   * Copyright (c) 2016-2019 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
   * for project information <a href="https://djutils.org" target="_blank"> https://djutils.org</a>. The DJUTILS project is
   * distributed under a three-clause BSD-style license, which can be found at
   * <a href="https://djutils.org/docs/license.html" target="_blank"> https://djutils.org/docs/license.html</a>.
   * </p>
   * @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="https://www.tudelft.nl/staff/p.knoppers/">Peter Knoppers</a>
   * @author <a href="https://www.transport.citg.tudelft.nl">Wouter Schakel</a>
   * @param <E> the type of content of this Set
   */
  public abstract class ImmutableAbstractSet<E> extends ImmutableAbstractCollection<E> implements ImmutableSet<E>
  {
      /** */
      private static final long serialVersionUID = 20160507L;
  
      /** the set that is wrapped, without giving access to methods that can change it. */
      private final Set<E> set;
  
      /**
       * Construct an abstract immutable set. Make sure that the argument is a safe copy of the set of the right type! Copying
       * does not take place in the Abstract class!
       * @param set Set&lt;E&gt;; a safe copy of the set to use for the immutable set
       * @param copyOrWrap Immutable; indicate whether the immutable is a copy or a wrap
       */
      protected ImmutableAbstractSet(final Set<E> set, final Immutable copyOrWrap)
      {
          super(copyOrWrap);
          Throw.whenNull(set, "the collection argument cannot be null");
          this.set = set;
      }
  
      /** {@inheritDoc} */
      @Override
      public final Collection<E> toCollection()
      {
          return toSet();
      }
  
      /** {@inheritDoc} */
      @Override
      protected Set<E> getCollection()
      {
          return this.set;
      }
  
      /** {@inheritDoc} */
      @Override
      public final int size()
      {
          return this.set.size();
      }
  
      /** {@inheritDoc} */
      @Override
      public final boolean isEmpty()
      {
          return this.set.isEmpty();
      }
  
      /** {@inheritDoc} */
      @Override
      public final boolean contains(final Object o)
      {
          return this.set.contains(o);
      }
  
      /** {@inheritDoc} */
      @Override
      public final Object[] toArray()
      {
          return this.set.toArray();
      }
  
      /** {@inheritDoc} */
      @Override
      public final <T> T[] toArray(final T[] a)
      {
          return this.set.toArray(a);
      }
  
      /** {@inheritDoc} */
      @Override
      public final ImmutableIterator<E> iterator()
      {
          return new ImmutableIterator<E>(this.set.iterator());
      }
 
     /** {@inheritDoc} */
     @Override
     public final void forEach(final Consumer<? super E> action)
     {
         this.set.forEach(action);
     }
 
     /** {@inheritDoc} */
     @Override
     public final Spliterator<E> spliterator()
     {
         return this.set.spliterator();
     }
 
     /** {@inheritDoc} */
     @Override
     public final boolean containsAll(final Collection<?> c)
     {
         return this.set.containsAll(c);
     }
 
     /** {@inheritDoc} */
     @Override
     public final boolean containsAll(final ImmutableCollection<?> c)
     {
         return this.set.containsAll(c.toCollection());
     }
 
     /** {@inheritDoc} */
     @Override
     public final Stream<E> stream()
     {
         return this.set.stream();
     }
 
     /** {@inheritDoc} */
     @Override
     public final Stream<E> parallelStream()
     {
         return this.set.parallelStream();
     }
 
     /** {@inheritDoc} */
     @Override
     public final boolean isWrap()
     {
         return this.copyOrWrap.isWrap();
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public int hashCode()
     {
         final int prime = 31;
         int result = 1;
         result = prime * result + ((this.set == null) ? 0 : this.set.hashCode());
         return result;
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings({"checkstyle:designforextension", "checkstyle:needbraces"})
     public boolean equals(final Object obj)
     {
         if (this == obj)
             return true;
         if (obj == null)
             return false;
         if (getClass() != obj.getClass())
             return false;
         ImmutableAbstractSet<?> other = (ImmutableAbstractSet<?>) obj;
         if (this.set == null)
         {
             if (other.set != null)
                 return false;
         }
         else if (!this.set.equals(other.set))
             return false;
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public String toString()
     {
         return "Immutable[" + this.set.toString() + "]";
     }
 }