documentterm.h

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/* Copyright 1999,2000,2001 BrightStation PLC
 * Copyright 2002 Ananova Ltd
 * Copyright 2003,2007,2018 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
 * USA
 */

#ifndef OM_HGUARD_DOCUMENTTERM_H
#define OM_HGUARD_DOCUMENTTERM_H

#include "debuglog.h"

#include <string>
#include <vector>

#include <xapian/types.h>

using std::string;
using std::vector;

class OmDocumentTerm {
    public:
    explicit OmDocumentTerm(Xapian::termcount wdf_)
        : wdf(wdf_)
    {
        LOGCALL_CTOR(DB, "OmDocumentTerm", wdf_);
    }

    Xapian::termcount wdf;

    mutable unsigned split = 0;

    void merge() const;

    typedef vector<Xapian::termpos> term_positions;

  private:
    mutable term_positions positions;

  public:
    const term_positions* get_vector_termpos() const {
        merge();
        return &positions;
    }

    Xapian::termcount positionlist_count() const {
        return positions.size();
    }

    void remove() {
        positions.clear();
        split = 1;
    }

    bool add_position(Xapian::termcount wdf_inc, Xapian::termpos termpos);

    void append_position(Xapian::termpos termpos) {
        positions.push_back(termpos);
    }

    void remove_position(Xapian::termpos tpos);

    Xapian::termpos remove_positions(Xapian::termpos termpos_first,
                                     Xapian::termpos termpos_last);

    bool increase_wdf(Xapian::termcount delta) {
        if (rare(is_deleted())) {
            split = 0;
            wdf = delta;
            return true;
        }
        wdf += delta;
        return false;
    }

    void decrease_wdf(Xapian::termcount delta) {
        // Saturating arithmetic - don't let the wdf go below zero.
        if (wdf >= delta) {
            wdf -= delta;
        } else {
            wdf = 0;
        }
    }

    Xapian::termcount get_wdf() const { return wdf; }

    bool is_deleted() const { return positions.empty() && split > 0; }

    string get_description() const;
};

#endif // OM_HGUARD_DOCUMENTTERM_H