/*
* Copyright 2015 Goldman Sachs.
*
* 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.gs.collections.impl.set.fixed;
import java.io.Serializable;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
import com.gs.collections.api.block.function.Function;
import com.gs.collections.api.block.procedure.Procedure;
import com.gs.collections.api.block.procedure.Procedure2;
import com.gs.collections.api.block.procedure.primitive.ObjectIntProcedure;
import com.gs.collections.api.ordered.OrderedIterable;
import com.gs.collections.api.set.MutableSet;
import com.gs.collections.api.tuple.Pair;
import com.gs.collections.impl.EmptyIterator;
import com.gs.collections.impl.factory.Sets;
import net.jcip.annotations.Immutable;
/**
* This class is a memory efficient list with no elements. It is created by calling Lists.fixedSize.of() which
* actually returns a singleton instance.
*/
@Immutable
final class EmptySet<T>
extends AbstractMemoryEfficientMutableSet<T>
implements Serializable
{
private static final long serialVersionUID = 1L;
private Object readResolve()
{
return Sets.fixedSize.of();
}
// Weird implementation of clone() is ok on final classes
@Override
public EmptySet<T> clone()
{
return this;
}
public int size()
{
return 0;
}
@Override
public boolean contains(Object obj)
{
return false;
}
public T getFirst()
{
return null;
}
public T getLast()
{
return null;
}
public void each(Procedure<? super T> procedure)
{
}
@Override
public void forEachWithIndex(ObjectIntProcedure<? super T> objectIntProcedure)
{
}
@Override
public <P> void forEachWith(Procedure2<? super T, ? super P> procedure, P parameter)
{
}
public Iterator<T> iterator()
{
return EmptyIterator.getInstance();
}
@Override
public boolean equals(Object other)
{
if (other == this)
{
return true;
}
if (!(other instanceof Set))
{
return false;
}
Set<?> set = (Set<?>) other;
return set.isEmpty();
}
@Override
public int hashCode()
{
return 0;
}
@Override
public T min(Comparator<? super T> comparator)
{
throw new NoSuchElementException();
}
@Override
public T max(Comparator<? super T> comparator)
{
throw new NoSuchElementException();
}
@Override
public T min()
{
throw new NoSuchElementException();
}
@Override
public T max()
{
throw new NoSuchElementException();
}
@Override
public <V extends Comparable<? super V>> T minBy(Function<? super T, ? extends V> function)
{
throw new NoSuchElementException();
}
@Override
public <V extends Comparable<? super V>> T maxBy(Function<? super T, ? extends V> function)
{
throw new NoSuchElementException();
}
/**
* @deprecated in 6.0. Use {@link OrderedIterable#zip(Iterable)} instead.
*/
@Deprecated
@Override
public <S> MutableSet<Pair<T, S>> zip(Iterable<S> that)
{
return Sets.fixedSize.of();
}
@Override
public <S, R extends Collection<Pair<T, S>>> R zip(Iterable<S> that, R target)
{
return target;
}
/**
* @deprecated in 6.0. Use {@link OrderedIterable#zipWithIndex()} instead.
*/
@Deprecated
@Override
public MutableSet<Pair<T, Integer>> zipWithIndex()
{
return Sets.fixedSize.of();
}
@Override
public <R extends Collection<Pair<T, Integer>>> R zipWithIndex(R target)
{
return target;
}
public MutableSet<T> with(T element)
{
return new SingletonSet<T>(element);
}
public MutableSet<T> without(T element)
{
return this;
}
}