/** @file
 * @brief Merge two PositionList objects using an OR operation.
 */
/* Copyright (C) 2007,2010,2017 Olly Betts
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see
 * <https://www.gnu.org/licenses/>.
 */

#ifndef XAPIAN_INCLUDED_ORPOSITIONLIST_H
#define XAPIAN_INCLUDED_ORPOSITIONLIST_H

#include "backends/positionlist.h"
#include "backends/postlist.h"

#include "xapian/error.h"
#include <algorithm>
#include <vector>

class OrPositionList : public PositionList {
    /// The PositionList sub-objects.
    std::vector<PositionList*> pls;

    /** Current positions of the subobjects.
     *
     *  This will be empty when this position list hasn't yet started.
     */
    std::vector<Xapian::termpos> current;

    /// Current position of this object.
    Xapian::termpos current_pos;

  public:
    OrPositionList() { }

    PositionList* gather(PostList* pl) {
        pls.clear();
        current.clear();
        pl->gather_position_lists(this);
        if (pls.size() == 1)
            return pls[0];
        return this;
    }

    void add_poslist(PositionList* poslist) {
        pls.push_back(poslist);
    }

    Xapian::termcount get_approx_size() const;

    Xapian::termpos back() const;

    Xapian::termpos get_position() const;

    bool next();

    bool skip_to(Xapian::termpos termpos);
};

#endif // XAPIAN_INCLUDED_ORPOSITIONLIST_H
