001/*
002 * This library is part of OpenCms -
003 * the Open Source Content Management System
004 *
005 * Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
006 *
007 * This library is free software; you can redistribute it and/or
008 * modify it under the terms of the GNU Lesser General Public
009 * License as published by the Free Software Foundation; either
010 * version 2.1 of the License, or (at your option) any later version.
011 *
012 * This library is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * For further information about Alkacon Software, please see the
018 * company website: http://www.alkacon.com
019 *
020 * For further information about OpenCms, please see the
021 * project website: http://www.opencms.org
022 *
023 * You should have received a copy of the GNU Lesser General Public
024 * License along with this library; if not, write to the Free Software
025 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
026 */
027
028package org.opencms.ade.configuration;
029
030import java.util.List;
031
032import com.google.common.base.Optional;
033
034/**
035 * Represents a sequence of inherited module/sitemap configurations, together with an index into that list.<p>
036 *
037 * Used for computing the configuration inheritance.
038 *
039 */
040public class CmsADEConfigurationSequence {
041
042    /** The list of configuration data. */
043    private List<CmsADEConfigDataInternal> m_configDatas;
044
045    /** The index for the current configuration. */
046    private int m_configIndex;
047
048    /**
049     * Creates a new instance for the given list of configuration data, with the index pointing to the last element.<p>
050     *
051     * @param configDatas the config data list
052     */
053    public CmsADEConfigurationSequence(List<CmsADEConfigDataInternal> configDatas) {
054
055        this(configDatas, configDatas.size() - 1);
056    }
057
058    /**
059     * Creates a new instance.<p>
060     *
061     * @param configDatas the configuration data list
062     * @param index the index into the list
063     */
064    protected CmsADEConfigurationSequence(List<CmsADEConfigDataInternal> configDatas, int index) {
065
066        assert(0 <= index) && (index < configDatas.size());
067        m_configDatas = configDatas;
068        m_configIndex = index;
069
070    }
071
072    /**
073     * Gets the current configuration data.<p>
074     *
075     * @return the current configuration data
076     */
077    public CmsADEConfigDataInternal getConfig() {
078
079        return m_configDatas.get(m_configIndex);
080    }
081
082    /**
083     * Returns a sequence which only differs from this instance in that its index is one less.<p>
084     *
085     * However, if the index of this instance is already 0, Optional.absent will be returned.
086     *
087     * @return the parent sequence, or Optional.absent if we are already at the start of the sequence
088     */
089    public Optional<CmsADEConfigurationSequence> getParent() {
090
091        if (m_configIndex <= 0) {
092            return Optional.absent();
093        }
094        return Optional.fromNullable(new CmsADEConfigurationSequence(m_configDatas, m_configIndex - 1));
095    }
096
097}