ImmutableEmptySet.java example

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gs-collections-master
/*
 * 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.immutable;

import java.io.IOException;
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.function.Function0;
import com.gs.collections.api.block.function.Function2;
import com.gs.collections.api.block.function.primitive.DoubleObjectToDoubleFunction;
import com.gs.collections.api.block.function.primitive.IntObjectToIntFunction;
import com.gs.collections.api.block.function.primitive.LongObjectToLongFunction;
import com.gs.collections.api.block.predicate.Predicate;
import com.gs.collections.api.block.predicate.Predicate2;
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.multimap.MutableMultimap;
import com.gs.collections.api.ordered.OrderedIterable;
import com.gs.collections.api.partition.set.PartitionImmutableSet;
import com.gs.collections.api.set.ImmutableSet;
import com.gs.collections.api.tuple.Pair;
import com.gs.collections.impl.EmptyIterator;
import com.gs.collections.impl.factory.Sets;
import com.gs.collections.impl.partition.set.PartitionUnifiedSet;
import net.jcip.annotations.Immutable;

/**
 * This is a zero element {@link ImmutableSet} which is created by calling the Sets.immutable.empty() method.
 */
@Immutable
final class ImmutableEmptySet<T>
        extends AbstractImmutableSet<T>
        implements Serializable
{
    static final ImmutableSet<?> INSTANCE = new ImmutableEmptySet<Object>();
    private static final PartitionImmutableSet<?> EMPTY = new PartitionUnifiedSet<Object>().toImmutable();

    private static final long serialVersionUID = 1L;

    @Override
    public boolean equals(Object other)
    {
        if (other == this)
        {
            return true;
        }
        return other instanceof Set && ((Set<?>) other).isEmpty();
    }

    @Override
    public int hashCode()
    {
        return 0;
    }

    @Override
    public ImmutableSet<T> newWith(T element)
    {
        return Sets.immutable.with(element);
    }

    @Override
    public ImmutableSet<T> newWithAll(Iterable<? extends T> elements)
    {
        return Sets.immutable.withAll(elements);
    }

    @Override
    public ImmutableSet<T> newWithout(T element)
    {
        return this;
    }

    @Override
    public ImmutableSet<T> newWithoutAll(Iterable<? extends T> elements)
    {
        return this;
    }

    public int size()
    {
        return 0;
    }

    @Override
    public boolean contains(Object obj)
    {
        return false;
    }

    @Override
    public ImmutableSet<T> tap(Procedure<? super T> procedure)
    {
        return this;
    }

    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 T getFirst()
    {
        return null;
    }

    public T getLast()
    {
        return null;
    }

    public Iterator<T> iterator()
    {
        return EmptyIterator.getInstance();
    }

    @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> ImmutableSet<Pair<T, S>> zip(Iterable<S> that)
    {
        return Sets.immutable.empty();
    }

    @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 ImmutableSet<Pair<T, Integer>> zipWithIndex()
    {
        return Sets.immutable.empty();
    }

    @Override
    public <R extends Collection<Pair<T, Integer>>> R zipWithIndex(R target)
    {
        return target;
    }

    @Override
    public ImmutableSet<T> select(Predicate<? super T> predicate)
    {
        return this;
    }

    @Override
    public ImmutableSet<T> reject(Predicate<? super T> predicate)
    {
        return this;
    }

    @Override
    public PartitionImmutableSet<T> partition(Predicate<? super T> predicate)
    {
        return (PartitionImmutableSet<T>) EMPTY;
    }

    @Override
    public <V> ImmutableSet<V> collect(Function<? super T, ? extends V> function)
    {
        return Sets.immutable.empty();
    }

    @Override
    public <V> ImmutableSet<V> collectIf(Predicate<? super T> predicate, Function<? super T, ? extends V> function)
    {
        return Sets.immutable.empty();
    }

    @Override
    public <V> ImmutableSet<V> flatCollect(Function<? super T, ? extends Iterable<V>> function)
    {
        return Sets.immutable.empty();
    }

    @Override
    public <V, R extends MutableMultimap<V, T>> R groupBy(Function<? super T, ? extends V> function, R target)
    {
        return target;
    }

    @Override
    public <V, R extends MutableMultimap<V, T>> R groupByEach(Function<? super T, ? extends Iterable<V>> function, R target)
    {
        return target;
    }

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

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

    @Override
    public <R extends Collection<T>> R select(Predicate<? super T> predicate, R target)
    {
        return target;
    }

    @Override
    public <P, R extends Collection<T>> R selectWith(Predicate2<? super T, ? super P> predicate, P parameter, R target)
    {
        return target;
    }

    @Override
    public <R extends Collection<T>> R reject(Predicate<? super T> predicate, R target)
    {
        return target;
    }

    @Override
    public <P, R extends Collection<T>> R rejectWith(Predicate2<? super T, ? super P> predicate, P parameter, R target)
    {
        return target;
    }

    @Override
    public <V, R extends Collection<V>> R collect(Function<? super T, ? extends V> function, R target)
    {
        return target;
    }

    @Override
    public <P, V, R extends Collection<V>> R collectWith(Function2<? super T, ? super P, ? extends V> function, P parameter, R target)
    {
        return target;
    }

    @Override
    public <V, R extends Collection<V>> R collectIf(Predicate<? super T> predicate, Function<? super T, ? extends V> function, R target)
    {
        return target;
    }

    @Override
    public T detectIfNone(Predicate<? super T> predicate, Function0<? extends T> function)
    {
        return function.value();
    }

    @Override
    public <V, R extends Collection<V>> R flatCollect(Function<? super T, ? extends Iterable<V>> function, R target)
    {
        return target;
    }

    @Override
    public T detect(Predicate<? super T> predicate)
    {
        return null;
    }

    @Override
    public int count(Predicate<? super T> predicate)
    {
        return 0;
    }

    @Override
    public <P> int countWith(Predicate2<? super T, ? super P> predicate, P parameter)
    {
        return 0;
    }

    @Override
    public boolean anySatisfy(Predicate<? super T> predicate)
    {
        return false;
    }

    @Override
    public boolean allSatisfy(Predicate<? super T> predicate)
    {
        return true;
    }

    @Override
    public boolean noneSatisfy(Predicate<? super T> predicate)
    {
        return true;
    }

    @Override
    public <P> boolean anySatisfyWith(Predicate2<? super T, ? super P> predicate, P parameter)
    {
        return false;
    }

    @Override
    public <P> boolean allSatisfyWith(Predicate2<? super T, ? super P> predicate, P parameter)
    {
        return true;
    }

    @Override
    public <P> boolean noneSatisfyWith(Predicate2<? super T, ? super P> predicate, P parameter)
    {
        return true;
    }

    @Override
    public <IV> IV injectInto(IV injectedValue, Function2<? super IV, ? super T, ? extends IV> function)
    {
        return injectedValue;
    }

    @Override
    public int injectInto(int injectedValue, IntObjectToIntFunction<? super T> intObjectToIntFunction)
    {
        return injectedValue;
    }

    @Override
    public long injectInto(long injectedValue, LongObjectToLongFunction<? super T> longObjectToLongFunction)
    {
        return injectedValue;
    }

    @Override
    public double injectInto(double injectedValue, DoubleObjectToDoubleFunction<? super T> doubleObjectToDoubleFunction)
    {
        return injectedValue;
    }

    @Override
    public String toString()
    {
        return "[]";
    }

    @Override
    public String makeString()
    {
        return "";
    }

    @Override
    public String makeString(String separator)
    {
        return "";
    }

    @Override
    public String makeString(String start, String separator, String end)
    {
        return start + end;
    }

    @Override
    public void appendString(Appendable appendable)
    {
    }

    @Override
    public void appendString(Appendable appendable, String separator)
    {
    }

    @Override
    public void appendString(Appendable appendable, String start, String separator, String end)
    {
        try
        {
            appendable.append(start);
            appendable.append(end);
        }
        catch (IOException e)
        {
            throw new RuntimeException(e);
        }
    }

    private Object writeReplace()
    {
        return new ImmutableSetSerializationProxy<T>(this);
    }
}