glass_postlist.h

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/* Copyright 1999,2000,2001 BrightStation PLC
 * Copyright 2002 Ananova Ltd
 * Copyright 2002-2024 Olly Betts
 * Copyright 2007,2009 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_GLASS_POSTLIST_H
#define XAPIAN_INCLUDED_GLASS_POSTLIST_H
 
#include <xapian/database.h>
 
#include "backends/leafpostlist.h"
#include "glass_defs.h"
#include "glass_inverter.h"
#include "glass_positionlist.h"
#include "omassert.h"
 
#include <memory>
#include <map>
#include <string>
#include <string_view>
 
class GlassCursor;
class GlassDatabase;
 
namespace Glass {
    class PostlistChunkReader;
    class PostlistChunkWriter;
    class RootInfo;
}
 
using Glass::RootInfo;
 
class GlassPostList : public LeafPostList {
    Xapian::Internal::intrusive_ptr<const GlassDatabase> this_db;
 
    GlassRePositionList* positionlist = NULL;
 
    bool have_started;
 
    bool is_last_chunk;
 
    bool is_at_end;
 
    std::unique_ptr<GlassCursor> cursor;
 
    Xapian::docid first_did_in_chunk;
 
    Xapian::docid last_did_in_chunk;
 
    const char * pos;
 
    const char * end;
 
    Xapian::docid did;
 
    Xapian::termcount wdf;
 
    Xapian::termcount wdf_upper_bound;
 
    GlassPostList(const GlassPostList &);
 
    void operator=(const GlassPostList &);
 
    bool next_in_chunk();
 
    void next_chunk();
 
    bool current_chunk_contains(Xapian::docid desired_did);
 
    void move_to_chunk_containing(Xapian::docid desired_did);
 
    bool move_forward_in_chunk_to_at_least(Xapian::docid desired_did);
 
    GlassPostList(Xapian::Internal::intrusive_ptr<const GlassDatabase> this_db_,
                  std::string_view term,
                  GlassCursor * cursor_);
 
    void init();
 
  public:
    GlassPostList(Xapian::Internal::intrusive_ptr<const GlassDatabase> this_db_,
                  std::string_view term,
                  bool keep_reference);
 
    ~GlassPostList();
 
    bool open_nearby_postlist(std::string_view term_,
                              bool need_read_pos,
                              LeafPostList*& pl) const;
 
    bool jump_to(Xapian::docid desired_did);
 
    Xapian::docid get_docid() const { Assert(have_started); return did; }
 
    Xapian::termcount get_wdf() const { Assert(have_started); return wdf; }
 
    PositionList *read_position_list();
 
    PositionList * open_position_list() const;
 
    PostList * next(double w_min);
 
    PostList * skip_to(Xapian::docid desired_did, double w_min);
 
    bool at_end() const { return is_at_end; }
 
    Xapian::termcount get_wdf_upper_bound() const;
 
    void get_docid_range(Xapian::docid& first, Xapian::docid& last) const;
 
    std::string get_description() const;
 
    static void read_freqs(const char** posptr,
                           const char* end,
                           Xapian::doccount* number_of_entries_ptr,
                           Xapian::termcount* collection_freq_ptr);
};
 
class GlassPostListTable : public GlassTable {
    mutable std::unique_ptr<GlassPostList> doclen_pl;
 
  public:
    GlassPostListTable(const std::string& path_, bool readonly_)
        : GlassTable("postlist", path_ + "/postlist.", readonly_),
          doclen_pl()
    { }
 
    GlassPostListTable(int fd, off_t offset_, bool readonly_)
        : GlassTable("postlist", fd, offset_, readonly_),
          doclen_pl()
    { }
 
    void open(int flags_, const RootInfo & root_info,
              glass_revision_number_t rev) {
        doclen_pl.reset(0);
        GlassTable::open(flags_, root_info, rev);
    }
 
    void merge_changes(std::string_view term,
                       const Inverter::PostingChanges& changes);
 
    void merge_doclen_changes(const std::map<Xapian::docid,
                                        Xapian::termcount>& doclens);
 
    Xapian::docid get_chunk(std::string_view tname,
                            Xapian::docid did, bool adding,
                            Glass::PostlistChunkReader** from,
                            Glass::PostlistChunkWriter** to);
 
    static std::string make_key(std::string_view term, Xapian::docid did) {
        return pack_glass_postlist_key(term, did);
    }
 
    static std::string make_key(std::string_view term) {
        return pack_glass_postlist_key(term);
    }
 
    bool term_exists(std::string_view term) const {
        return key_exists(make_key(term));
    }
 
    void get_freqs(std::string_view term,
                   Xapian::doccount* termfreq_ptr,
                   Xapian::termcount* collfreq_ptr,
                   Xapian::termcount* wdfub_ptr = NULL) const;
 
    Xapian::termcount get_doclength(Xapian::docid did,
                                    Xapian::Internal::intrusive_ptr<const GlassDatabase> db) const;
 
    bool document_exists(Xapian::docid did,
                         Xapian::Internal::intrusive_ptr<const GlassDatabase> db) const;
 
    void get_used_docid_range(Xapian::docid & first,
                              Xapian::docid & last) const;
};
#ifdef DISABLE_GPL_LIBXAPIAN
# error GPL source we cannot relicense included in libxapian
#endif
 
#endif /* XAPIAN_INCLUDED_GLASS_POSTLIST_H */