glass_postlist.h

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/* Copyright 1999,2000,2001 BrightStation PLC
 * Copyright 2002 Ananova Ltd
 * Copyright 2002,2003,2004,2005,2007,2008,2009,2011,2013,2014,2015 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
 * USA
 */

#ifndef OM_HGUARD_GLASS_POSTLIST_H
#define OM_HGUARD_GLASS_POSTLIST_H

#include <xapian/database.h>

#include "glass_defs.h"
#include "glass_inverter.h"
#include "glass_positionlist.h"
#include "api/leafpostlist.h"
#include "omassert.h"

#include "autoptr.h"
#include <map>
#include <string>

using namespace std;

class GlassCursor;
class GlassDatabase;

namespace Glass {
    class PostlistChunkReader;
    class PostlistChunkWriter;
    class RootInfo;
}

using Glass::RootInfo;

class GlassPostList;

class GlassPostListTable : public GlassTable {
    mutable AutoPtr<GlassPostList> doclen_pl;

  public:
    GlassPostListTable(const 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(const string& term,
                       const Inverter::PostingChanges& changes);

    void merge_doclen_changes(const map<Xapian::docid,
                                        Xapian::termcount>& doclens);

    Xapian::docid get_chunk(const string& tname,
                            Xapian::docid did, bool adding,
                            Glass::PostlistChunkReader** from,
                            Glass::PostlistChunkWriter** to);

    static string make_key(const string& term, Xapian::docid did) {
        return pack_glass_postlist_key(term, did);
    }

    static string make_key(const string & term) {
        return pack_glass_postlist_key(term);
    }

    bool term_exists(const string & term) const {
        return key_exists(make_key(term));
    }

    void get_freqs(const std::string & 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;
};

class GlassPostList : public LeafPostList {
    Xapian::Internal::intrusive_ptr<const GlassDatabase> this_db;

    GlassPositionList positionlist;

    bool have_started;

    bool is_last_chunk;

    bool is_at_end;

    AutoPtr<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::doccount number_of_entries;

    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_,
                  const string & term,
                  GlassCursor * cursor_);

    void init();

  public:
    GlassPostList(Xapian::Internal::intrusive_ptr<const GlassDatabase> this_db_,
                  const string & term,
                  bool keep_reference);

    ~GlassPostList();

    LeafPostList * open_nearby_postlist(const std::string & term_) const;

    bool jump_to(Xapian::docid desired_did);

    Xapian::doccount get_termfreq() const { return number_of_entries; }

    Xapian::docid get_docid() const { Assert(have_started); return did; }

    Xapian::termcount get_doclength() const;

    Xapian::termcount get_unique_terms() const;

    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;

    std::string get_description() const;

    static void read_number_of_entries(const char ** posptr,
                                       const char * end,
                                       Xapian::doccount * number_of_entries_ptr,
                                       Xapian::termcount * collection_freq_ptr);
};

#endif /* OM_HGUARD_GLASS_POSTLIST_H */