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package org.aksw.commons.collections;

import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Objects;

/**
 * Created by Claus Stadler
 * Date: Nov 1, 2010
 * Time: 10:22:25 PM
 */
public class IteratorUtils {
    public static  Iterable makeIterable(Iterator iterator) {
        return new IteratorIterable(iterator);
    }

    public static  T expectOneItem(Iterator iterator) {
        T result = null;
        if (!iterator.hasNext()) {
            throw new IllegalArgumentException("Exactly one item expected in stream; got none");
        }

        result = iterator.next();

        if (iterator.hasNext()) {
            throw new IllegalArgumentException("Exactly one item expected in stream; got multiple");
        }

        return result;

    }
    public static  T expectZeroOrOneItems(Iterator iterator) {
        T result;
        if (!iterator.hasNext()) {
            result = null;
        } else {
            result = expectOneItem(iterator);
        }

        return result;
    }

    /** Similar to guava's Iterators.limit but with long argument*/
    public static  Iterator limit(Iterator iterator, long limitSize) {
        Objects.requireNonNull(iterator);

        return new Iterator() {
            protected long count;

            @Override
            public boolean hasNext() {
                return count < limitSize && iterator.hasNext();
            }

            @Override
            public T next() {
                if (!hasNext()) {
                    throw new NoSuchElementException();
                }
                count++;
                return iterator.next();
            }

            @Override
            public void remove() {
                iterator.remove();
            }
        };
    }

}