001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 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.ArrayList;
023import java.util.Collection;
024import java.util.List;
025
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     * List of nodes.
035     */
036    private final List<? extends NodeInfo> items;
037    /**
038     * Current index.
039     */
040    private int index;
041
042    /**
043     * Constructor for {@code ReverseListIterator} class.
044     *
045     * @param items the collection of nodes.
046     */
047    public ReverseListIterator(Collection<? extends NodeInfo> items) {
048        if (items == null) {
049            this.items = null;
050            index = -1;
051        }
052        else {
053            this.items = new ArrayList<>(items);
054            index = items.size() - 1;
055        }
056    }
057
058    /**
059     * Get the next item in the sequence.
060     *
061     * @return the next Item. If there are no more nodes, return null.
062     */
063    @Override
064    public NodeInfo next() {
065        final NodeInfo result;
066        if (index == -1) {
067            result = null;
068        }
069        else {
070            result = items.get(index);
071            index--;
072        }
073        return result;
074    }
075}