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package fiftyone.mobile.detection.entities;

import fiftyone.mobile.detection.readers.BinaryReader;
import java.util.Iterator;

/* *********************************************************************
 * This Source Code Form is copyright of 51Degrees Mobile Experts Limited. 
 * Copyright 2014 51Degrees Mobile Experts Limited, 5 Charlotte Close,
 * Caversham, Reading, Berkshire, United Kingdom RG4 7BY
 * 
 * This Source Code Form is the subject of the following patent 
 * applications, owned by 51Degrees Mobile Experts Limited of 5 Charlotte
 * Close, Caversham, Reading, Berkshire, United Kingdom RG4 7BY: 
 * European Patent Application No. 13192291.6; and 
 * United States Patent Application Nos. 14/085,223 and 14/085,301.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0.
 * 
 * If a copy of the MPL was not distributed with this file, You can obtain
 * one at http://mozilla.org/MPL/2.0/.
 * 
 * This Source Code Form is "Incompatible With Secondary Licenses", as
 * defined by the Mozilla Public License, v. 2.0.
 * ********************************************************************* */
/**
 * Class implements the logic of IEnumerable in C#. When you need to read a 
 * specific number of integer objects from the data file it's best to do so 
 * on the as-needed basis instead of loading everything in to memory. This class 
 * provides a way to read the integers one by one.
 */
public class Enumerable implements Iterator, Iterable {
    /**
     * Reader set to the position at the start of the list.
     */
    private final BinaryReader reader;
    /**
     * The number of integers to read to form the array.
     */
    int max;
    /**
     * Current position.
     */
    int count;

    /**
     * An enumerable that can be used to read through the entries.
     * @param reader Reader set to the position at the start of the list.
     * @param max 
     */
    public Enumerable(BinaryReader reader, int max) {
        this.count = 0;
        this.reader = reader;
        this.max = max;
    }

    /**
     * Get the next element.
     * @return integer entry.
     */
    public int getNext() {
        Integer value = null;
        if (count < max) {
            value = reader.readInt32();
            count++;
            return value;
        }
        return value;
    }

    /**
     * Returns true if there are more values to read, false otherwise.
     * @return true if there are more values to read, false otherwise.
     */
    @Override
    public boolean hasNext() {
        return count < max;
    }

    /**
     * Reads the next integer and returns it.
     * @return the next integer in a sequence. Null if current > max.
     */
    @Override
    public Integer next() {
        return getNext();
    }

    /**
     * Not supported.
     */
    @Override
    public void remove() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    /**
     * Returns this object.
     * @return this object.
     */
    @Override
    public Iterator iterator() {
        return this;
    }
    
}