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 net.sf.saxon.om.NodeInfo;
023import net.sf.saxon.om.SequenceIterator;
024
025/**
026 * Recursive-free implementation of the following axis iterator.
027 */
028public class FollowingIterator implements SequenceIterator {
029
030    /**
031     * Ancestor axis iterator.
032     */
033    private final SequenceIterator ancestorEnum;
034    /**
035     * Following-sibling axis iterator.
036     */
037    private SequenceIterator siblingEnum;
038    /**
039     * Descendant axis iterator.
040     */
041    private SequenceIterator descendantEnum;
042
043    /**
044     * Create an iterator over the "following" axis.
045     *
046     * @param start the initial context node.
047     */
048    public FollowingIterator(NodeInfo start) {
049        ancestorEnum = start.iterateAncestorAxis(null);
050        siblingEnum = start.iterateFollowingSiblingAxis(null);
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        NodeInfo result = null;
061
062        do {
063            if (descendantEnum != null) {
064                result = (NodeInfo) descendantEnum.next();
065            }
066
067            if (result == null) {
068                result = (NodeInfo) siblingEnum.next();
069                if (result != null) {
070                    descendantEnum = result.iterateDescendantAxis(null);
071                }
072            }
073
074            if (result == null) {
075                final NodeInfo parent = (NodeInfo) ancestorEnum.next();
076                if (parent == null) {
077                    break;
078                }
079                siblingEnum = parent.iterateFollowingSiblingAxis(null);
080            }
081        } while (result == null);
082        return result;
083    }
084
085}