001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2026 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018///////////////////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.xpath.iterators;
021
022import java.util.Collection;
023import java.util.List;
024
025import com.puppycrawl.tools.checkstyle.utils.UnmodifiableCollectionUtil;
026import net.sf.saxon.om.NodeInfo;
027import net.sf.saxon.tree.iter.AxisIterator;
028
029/**
030 * Iterates list in backward direction.
031 */
032public class ReverseListIterator implements AxisIterator {
033
034    /**
035     * List of nodes.
036     */
037    private final List<? extends NodeInfo> items;
038    /**
039     * Current index.
040     */
041    private int index;
042
043    /**
044     * Constructor for {@code ReverseListIterator} class.
045     *
046     * @param items the collection of nodes.
047     */
048    public ReverseListIterator(Collection<? extends NodeInfo> items) {
049        this.items = UnmodifiableCollectionUtil.unmodifiableList(items);
050        index = this.items.size() - 1;
051    }
052
053    /**
054     * Get the next item in the sequence.
055     *
056     * @return the next Item. If there are no more nodes, return null.
057     */
058    @Override
059    public NodeInfo next() {
060        final NodeInfo result;
061        if (index == -1) {
062            result = null;
063        }
064        else {
065            result = items.get(index);
066            index--;
067        }
068        return result;
069    }
070
071}