extraweightpostlist.h

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/* Copyright 1999,2000,2001 BrightStation PLC
 * Copyright 2001 Ananova Ltd
 * Copyright 2003,2004,2007,2009,2011,2014 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_EXTRAWEIGHTPOSTLIST_H
#define OM_HGUARD_EXTRAWEIGHTPOSTLIST_H

#include "multimatch.h"
#include "omassert.h"

namespace Xapian {
    class Weight;
}

class ExtraWeightPostList : public PostList {
    private:
        PostList * pl;
        Xapian::Weight * wt;
        MultiMatch * matcher;
        double max_weight;

    public:
        Xapian::doccount get_termfreq_max() const {
            return pl->get_termfreq_max();
        }
        Xapian::doccount get_termfreq_min() const {
            return pl->get_termfreq_min();
        }
        Xapian::doccount get_termfreq_est() const {
            return pl->get_termfreq_est();
        }

        Xapian::docid get_docid() const { return pl->get_docid(); }

        double get_weight() const {
            /* Second parameter of get_sumextra is number of unique terms in doc, which has been put
             * to maintain consistency with get_sumpart, As of now none of weighting scheme is using
             * it. Current 0 is being passed, change it to pl->get_unique_terms() in case you
             * need access uniq_terms. */
            double sumextra = wt->get_sumextra(pl->get_doclength(), 0);
            AssertRel(sumextra, <=, max_weight);
            return pl->get_weight() + sumextra;
        }

        double get_maxweight() const {
            return pl->get_maxweight() + max_weight;
        }

        double recalc_maxweight() {
            return pl->recalc_maxweight() + max_weight;
        }

        PostList *next(double w_min) {
            PostList *p = pl->next(w_min - max_weight);
            if (p) {
                delete pl;
                pl = p;
                if (matcher) matcher->recalc_maxweight();
            }
            return NULL;
        }

        PostList *skip_to(Xapian::docid did, double w_min) {
            PostList *p = pl->skip_to(did, w_min - max_weight);
            if (p) {
                delete pl;
                pl = p;
                if (matcher) matcher->recalc_maxweight();
            }
            return NULL;
        }

        bool at_end() const { return pl->at_end(); }

        std::string get_description() const {
            return "( ExtraWeight " + pl->get_description() + " )";
        }

        virtual Xapian::termcount get_doclength() const {
            return pl->get_doclength();
        }

        virtual Xapian::termcount get_unique_terms() const {
            return pl->get_unique_terms();
        }

        ExtraWeightPostList(PostList * pl_, Xapian::Weight *wt_,
                            MultiMatch *matcher_)
            : pl(pl_), wt(wt_), matcher(matcher_),
              max_weight(wt->get_maxextra())
        { }

        ~ExtraWeightPostList() {
            delete pl;
            delete wt;
        }

        Xapian::termcount count_matching_subqs() const {
            return pl->count_matching_subqs();
        }
};

#endif /* OM_HGUARD_EXTRAWEIGHTPOSTLIST_H */