maxpostlist.h

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/* Copyright (C) 2007,2009,2010,2011,2012,2013 Olly Betts
 * Copyright (C) 2009 Lemur Consulting Ltd
 *
 * 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 XAPIAN_INCLUDED_MAXPOSTLIST_H
#define XAPIAN_INCLUDED_MAXPOSTLIST_H

#include "multimatch.h"
#include "api/postlist.h"
#include <algorithm>

class MultiMatch;

class MaxPostList : public PostList {
    void operator=(const MaxPostList &);

    MaxPostList(const MaxPostList &);

    Xapian::docid did;

    size_t n_kids;

    PostList ** plist;

    double max_cached;

    Xapian::doccount db_size;

    MultiMatch *matcher;

    void erase_sublist(size_t i) {
        delete plist[i];
        --n_kids;
        for (size_t j = i; j < n_kids; ++j) {
            plist[j] = plist[j + 1];
        }
        matcher->recalc_maxweight();
    }

  public:
    template<class RandomItor>
    MaxPostList(RandomItor pl_begin, RandomItor pl_end,
                MultiMatch * matcher_, Xapian::doccount db_size_)
        : did(0), n_kids(pl_end - pl_begin), plist(NULL),
          max_cached(0), db_size(db_size_), matcher(matcher_)
    {
        plist = new PostList * [n_kids];
        std::copy(pl_begin, pl_end, plist);
    }

    ~MaxPostList();

    Xapian::doccount get_termfreq_min() const;

    Xapian::doccount get_termfreq_max() const;

    Xapian::doccount get_termfreq_est() const;

    double get_maxweight() const;

    Xapian::docid get_docid() const;

    Xapian::termcount get_doclength() const;

    Xapian::termcount get_unique_terms() const;

    double get_weight() const;

    bool at_end() const;

    double recalc_maxweight();

    PositionList * read_position_list() {
        return NULL;
    }

    PostList* next(double w_min);

    PostList* skip_to(Xapian::docid, double w_min);

    std::string get_description() const;

    Xapian::termcount get_wdf() const;

    // Note - we don't need to implement get_termfreq_est_using_stats() because
    // an OP_MAX when used as a child of a synonym will be optimised to an OR.

    Xapian::termcount count_matching_subqs() const;
};

#endif // XAPIAN_INCLUDED_MAXPOSTLIST_H