/*
 * Copyright 2011 Goldman Sachs.
 *
 * Licensed 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 com.gs.collections.impl.list.mutable;

import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;

public class MutableIterator<T> implements Iterator<T>
{
    /**
     * Index of element to be returned by subsequent call to next.
     */
    protected int currentIndex;

    /**
     * Index of element returned by most recent call to next or previous.  Reset to -1 if this element is deleted by
     * a call to remove.
     */
    protected int lastIndex = -1;
    protected final List<T> list;

    public MutableIterator(List<T> list)
    {
        this.list = list;
    }

    public boolean hasNext()
    {
        return this.currentIndex != this.list.size();
    }

    public T next()
    {
        try
        {
            T next = this.list.get(this.currentIndex);
            this.lastIndex = this.currentIndex++;
            return next;
        }
        catch (IndexOutOfBoundsException ignored)
        {
            throw new NoSuchElementException();
        }
    }

    public void remove()
    {
        if (this.lastIndex == -1)
        {
            throw new IllegalStateException();
        }
        this.list.remove(this.lastIndex);
        if (this.lastIndex < this.currentIndex)
        {
            this.currentIndex--;
        }
        this.lastIndex = -1;
    }
}