glass_positionlist.h

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/* Copyright (C) 2005-2024 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_GLASS_POSITIONLIST_H
#define XAPIAN_INCLUDED_GLASS_POSITIONLIST_H
 
#include <xapian/types.h>
 
#include "bitstream.h"
#include "glass_cursor.h"
#include "glass_lazytable.h"
#include "pack.h"
#include "backends/positionlist.h"
 
#include <string>
 
class GlassBasePositionList : public PositionList {
    GlassBasePositionList(const GlassBasePositionList&) = delete;
 
    GlassBasePositionList& operator=(const GlassBasePositionList&) = delete;
 
  protected:
    BitReader rd;
 
    Xapian::termpos current_pos;
 
    Xapian::termpos last;
 
    Xapian::termcount size;
 
    bool have_started;
 
    void set_data(std::string_view data);
 
  public:
    GlassBasePositionList() {}
 
    Xapian::termcount get_approx_size() const;
 
    Xapian::termpos back() const;
 
    Xapian::termpos get_position() const;
 
    bool next();
 
    bool skip_to(Xapian::termpos termpos);
};
 
class GlassPositionList : public GlassBasePositionList {
    std::string pos_data;
 
    GlassPositionList(const GlassPositionList&) = delete;
 
    GlassPositionList& operator=(const GlassPositionList&) = delete;
 
  public:
    explicit
    GlassPositionList(std::string&& data);
};
 
class GlassRePositionList : public GlassBasePositionList {
    GlassCursor cursor;
 
    GlassRePositionList(const GlassRePositionList&) = delete;
 
    GlassRePositionList& operator=(const GlassRePositionList&) = delete;
 
  public:
    explicit
    GlassRePositionList(const GlassTable* table)
        : cursor(table) {}
 
    void assign_data(std::string&& data);
 
    void read_data(Xapian::docid did,
                   std::string_view term);
};
 
class GlassPositionListTable : public GlassLazyTable {
  public:
    static std::string make_key(Xapian::docid did, std::string_view term) {
        std::string key;
        pack_string_preserving_sort(key, term);
        pack_uint_preserving_sort(key, did);
        return key;
    }
 
    GlassPositionListTable(const std::string& dbdir, bool readonly)
        : GlassLazyTable("position", dbdir + "/position.", readonly) { }
 
    GlassPositionListTable(int fd, off_t offset_, bool readonly_)
        : GlassLazyTable("position", fd, offset_, readonly_) { }
 
    GlassPositionList* open_position_list(Xapian::docid did,
                                          std::string_view term) {
        std::string pos_data;
        if (!get_exact_entry(make_key(did, term), pos_data))
            return nullptr;
 
        return new GlassPositionList(std::move(pos_data));
    }
 
    void pack(std::string& s, const Xapian::VecCOW<Xapian::termpos>& vec) const;
 
    void set_positionlist(Xapian::docid did, std::string_view tname,
                          std::string_view s) {
        add(make_key(did, tname), s);
    }
 
    void delete_positionlist(Xapian::docid did, std::string_view tname) {
        del(make_key(did, tname));
    }
 
    Xapian::termcount positionlist_count(std::string_view data) const;
 
    Xapian::termcount positionlist_count(Xapian::docid did,
                                         std::string_view term) const;
};
 
#endif /* XAPIAN_INCLUDED_GLASS_POSITIONLIST_H */