G-Set.java

package crdt.sets;

import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;

import crdt.CRDT;

/**
 * Grow only set. Items can only be added
 */
public class GSet<T> implements CRDT<GSet<T>> {

    private static final long serialVersionUID = 1L;

    private Set<T> items = new LinkedHashSet<T>();

    public void add(T item) {
        items.add(item);
    }

    public Set<T> get() {
        return Collections.unmodifiableSet(items);
    }

    /**
     * Merge another set into this one
     */

    public void merge(GSet<T> set) {
        items.addAll(set.items);
    }

    public boolean contains(T item) {
        return items.contains(item);
    }

    public void addAll(Collection<T> itemToAdd) {
        items.addAll(itemToAdd);
    }

    public GSet<T> copy() {
        GSet<T> copy = new GSet<T>();
        copy.items = new LinkedHashSet<T>(items);
        return copy;
    }
}