LazyHashSet.java

package com.github.tuserver.api.utils;

import java.util.Collection;
import java.util.Iterator;
import java.util.Set;

public abstract class LazyHashSet<E> implements Set<E> {
	Set<E> reference = null;

	@Override
	public int size() {
		return getReference().size();
	}

	@Override
	public boolean isEmpty() {
		return getReference().isEmpty();
	}

	@Override
	public boolean contains(Object o) {
		return getReference().contains(o);
	}

	@Override
	public Iterator<E> iterator() {
		return getReference().iterator();
	}

	@Override
	public Object[] toArray() {
		return getReference().toArray();
	}

	@Override
	public <T> T[] toArray(T[] a) {
		return getReference().toArray(a);
	}

	@Override
	public boolean add(E o) {
		return getReference().add(o);
	}

	@Override
	public boolean remove(Object o) {
		return getReference().remove(o);
	}

	@Override
	public boolean containsAll(Collection<?> c) {
		return getReference().containsAll(c);
	}

	@Override
	public boolean addAll(Collection<? extends E> c) {
		return getReference().addAll(c);
	}

	@Override
	public boolean retainAll(Collection<?> c) {
		return getReference().retainAll(c);
	}

	@Override
	public boolean removeAll(Collection<?> c) {
		return getReference().removeAll(c);
	}

	@Override
	public void clear() {
		getReference().clear();
	}

	public Set<E> getReference() {
		Set<E> reference = this.reference;
		if (reference != null) {
			return reference;
		}
		return this.reference = makeReference();
	}

	abstract Set<E> makeReference();

	public boolean isLazy() {
		return reference == null;
	}

	@Override
	public int hashCode() {
		return 157 * getReference().hashCode();
	}

	@Override
	public boolean equals(Object obj) {
		if (obj == this) {
			return true;
		}
		if (obj == null || this.getClass() != obj.getClass()) {
			return false;
		}
		LazyHashSet<?> that = (LazyHashSet<?>) obj;
		return (this.isLazy() && that.isLazy()) || this.getReference().equals(that.getReference());
	}

	@Override
	public String toString() {
		return getReference().toString();
	}
}