/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.internal.helpers.collection;

import java.util.Iterator;

/**
 * Wraps an {@link Iterable} so that it returns items of another type. The
 * iteration is done lazily.
 *
 * @param <T> the type of items to return
 * @param <U> the type of items to wrap/convert from
 */
public abstract class IterableWrapper<T, U> implements Iterable<T> {
    private Iterable<U> source;

    public IterableWrapper(Iterable<U> iterableToWrap) {
        this.source = iterableToWrap;
    }

    protected abstract T underlyingObjectToObject(U object);

    @Override
    public Iterator<T> iterator() {
        return new MyIteratorWrapper(source.iterator());
    }

    private class MyIteratorWrapper extends IteratorWrapper<T, U> {
        MyIteratorWrapper(Iterator<U> iteratorToWrap) {
            super(iteratorToWrap);
        }

        @Override
        protected T underlyingObjectToObject(U object) {
            return IterableWrapper.this.underlyingObjectToObject(object);
        }
    }
}
