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The Adobe Experience Manager SDK

There is a newer version: 2024.11.18751.20241128T090041Z-241100

/*************************************************************************
* ADOBE CONFIDENTIAL
* ___________________
*
* Copyright 2014 Adobe
* All Rights Reserved.
*
* NOTICE: All information contained herein is, and remains
* the property of Adobe and its suppliers, if any. The intellectual
* and technical concepts contained herein are proprietary to Adobe
* and its suppliers and are protected by all applicable intellectual
* property laws, including trade secret and copyright laws.
* Dissemination of this information or reproduction of this material
* is strictly forbidden unless prior written permission is obtained
* from Adobe.
**************************************************************************/
package com.adobe.granite.ui.components;

import java.util.Iterator;

import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;

/**
 * A wrapper iterator to supports paging.
 * 
 * If you have access to Collection 4.1, it is recommended to use
 * {@code IteratorUtils#boundedIterator(Iterator, long, long)} instead.
 */
public class PagingIterator implements Iterator {
    private Iterator it;

    private Integer offset;

    private Integer limit;

    private int limitCounter = 0;

    /**
     * Instantiates a new paging wrapper of the given iterator.
     * 
     * The iterator is iterated immediately as per {@code offset}.
     *
     * @param it
     *            The iterator to wrap
     * @param offset
     *            The offset of the paging; {@code null} to do paging without
     *            offset.
     * @param limit
     *            The limit of the paging; {@code null} to do paging without limit.
     * @throws IllegalArgumentException
     *             When either offset or limit is negative
     */
    public PagingIterator(@Nonnull Iterator it, @CheckForNull Integer offset, @CheckForNull Integer limit)
            throws IllegalArgumentException {
        this.it = it;
        this.offset = offset;
        this.limit = limit;

        if (offset != null && offset < 0) {
            throw new IllegalArgumentException("offset is negative");
        }

        if (limit != null && limit < 0) {
            throw new IllegalArgumentException("limit is negative");
        }

        doOffset();
    }

    private void doOffset() {
        if (offset == null) {
            return;
        }

        for (int i = 0; i < offset && it.hasNext(); i++) {
            it.next();
        }
    }

    @Override
    public boolean hasNext() {
        if (limit == null) {
            return it.hasNext();
        }

        return limitCounter < limit && it.hasNext();
    }

    @Override
    public E next() {
        E next = it.next();
        limitCounter++;
        return next;
    }

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