/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.tinkerpop.gremlin.util.iterator;

import org.apache.tinkerpop.gremlin.process.traversal.util.FastNoSuchElementException;

import java.io.Serializable;
import java.util.Iterator;

/**
 * @author Marko A. Rodriguez (http://markorodriguez.com)
 */
final class DoubleIterator<T> implements Iterator<T>, Serializable {

    private T a;
    private T b;
    private char current = 'a';

    protected DoubleIterator(final T a, final T b) {
        this.a = a;
        this.b = b;
    }

    @Override
    public boolean hasNext() {
        return this.current != 'x';
    }

    @Override
    public void remove() {
        if (this.current == 'b')
            this.a = null;
        else if (this.current == 'x')
            this.b = null;
    }

    @Override
    public T next() {
        if (this.current == 'x')
            throw FastNoSuchElementException.instance();
        else {
            if (this.current == 'a') {
                this.current = 'b';
                return this.a;
            } else {
                this.current = 'x';
                return this.b;
            }
        }
    }
}