org.javimmutable.collections.inorder.JImmutableInsertOrderSet Maven / Gradle / Ivy

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// Burton Computer Corporation
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package org.javimmutable.collections.inorder;

import org.javimmutable.collections.GenericCollector;
import org.javimmutable.collections.JImmutableMap;
import org.javimmutable.collections.JImmutableSet;
import org.javimmutable.collections.common.AbstractJImmutableSetUsingMap;
import org.javimmutable.collections.common.GenericSetBuilder;
import org.javimmutable.collections.serialization.JImmutableInsertOrderSetProxy;

import javax.annotation.Nonnull;
import javax.annotation.concurrent.Immutable;
import java.io.Serializable;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.stream.Collector;

/**
 * JImmutableSet implementation built on top of a JImmutableInsertOrderMap.  During iteration
 * elements are returned in the same order they were inserted into the set.  Performance is
 * slower than hash or tree sets but should be sufficient for most algorithms where insert
 * order matters.
 */
@Immutable
public class JImmutableInsertOrderSet
    extends AbstractJImmutableSetUsingMap
    implements Serializable
{
    @SuppressWarnings("unchecked")
    private static final JImmutableInsertOrderSet EMPTY = new JImmutableInsertOrderSet(JImmutableInsertOrderMap.of());
    private static final long serialVersionUID = -121805;

    private JImmutableInsertOrderSet(JImmutableMap map)
    {
        super(map);
    }

    @SuppressWarnings("unchecked")
    public static  JImmutableInsertOrderSet of()
    {
        return EMPTY;
    }

    @Nonnull
    public static  JImmutableSet.Builder builder()
    {
        return new GenericSetBuilder<>(JImmutableInsertOrderMap.builder(), map -> map.isEmpty() ? of() : new JImmutableInsertOrderSet<>(map));
    }

    @Nonnull
    @Override
    public JImmutableSet deleteAll()
    {
        return of();
    }

    @Nonnull
    @Override
    public Collector> setCollector()
    {
        return GenericCollector.ordered(this, deleteAll(), a -> a.isEmpty(), (a, v) -> a.insert(v), (a, b) -> a.insertAll(b));
    }

    @Override
    protected JImmutableSet create(JImmutableMap map)
    {
        return new JImmutableInsertOrderSet<>(map);
    }

    @Override
    protected Set emptyMutableSet()
    {
        return new LinkedHashSet<>();
    }

    private Object writeReplace()
    {
        return new JImmutableInsertOrderSetProxy(this);
    }
}