leafpostlist.h

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/* Copyright (C) 2007-2024 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, see
 * <https://www.gnu.org/licenses/>.
 */
 
#ifndef XAPIAN_INCLUDED_LEAFPOSTLIST_H
#define XAPIAN_INCLUDED_LEAFPOSTLIST_H
 
#include "postlist.h"
 
#include <algorithm>
#include <string>
#include <string_view>
 
namespace Xapian {
    class Weight;
}
 
class LeafPostList : public PostList {
    void operator=(const LeafPostList &) = delete;
 
    LeafPostList(const LeafPostList &) = delete;
 
  protected:
    const Xapian::Weight* weight = nullptr;
 
    std::string term;
 
    Xapian::termcount collfreq;
 
    explicit LeafPostList(std::string_view term_)
        : term(term_) { }
 
  public:
    ~LeafPostList();
 
    Xapian::termcount get_collfreq() const { return collfreq; }
 
    void set_termweight(const Xapian::Weight * weight_) {
        // This method shouldn't be called more than once on the same object.
        Assert(!weight);
        weight = weight_;
    }
 
    double resolve_lazy_termweight(Xapian::Weight * weight_,
                                   Xapian::Weight::Internal * stats,
                                   Xapian::termcount qlen,
                                   Xapian::termcount wqf,
                                   double factor,
                                   const Xapian::Database::Internal* shard)
    {
        weight_->init_(*stats, qlen, term, wqf, factor, shard, this);
        // There should be an existing LazyWeight set already.
        Assert(weight);
        const Xapian::Weight * const_weight_ = weight_;
        std::swap(weight, const_weight_);
        delete const_weight_;
        // We get such terms from the database so they should exist.
        Assert(get_termfreq() > 0);
        double result = weight->get_maxpart();
        double& max_part = stats->termfreqs[term].max_part;
        max_part = std::max(max_part, result);
        return result;
    }
 
    double get_weight(Xapian::termcount doclen,
                      Xapian::termcount unique_terms,
                      Xapian::termcount wdfdocmax) const;
 
    double recalc_maxweight();
 
    Xapian::termcount count_matching_subqs() const;
 
    void gather_position_lists(OrPositionList* orposlist);
 
    virtual bool open_nearby_postlist(std::string_view term_,
                                      bool need_read_pos,
                                      LeafPostList*& pl) const;
 
    virtual Xapian::termcount get_wdf_upper_bound() const = 0;
 
    const std::string& get_term() const { return term; }
 
    void set_term(std::string_view term_) { term = term_; }
};
 
#endif // XAPIAN_INCLUDED_LEAFPOSTLIST_H