xapian-core/backends/multi/multi_termlist.h

   1 /** @file
   2  * @brief Adapter class for a TermList in a multidatabase
   3  */
   4 /* Copyright (C) 2007,2010,2013,2017,2024 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2 of the
   9  * License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #ifndef XAPIAN_INCLUDED_MULTI_TERMLIST_H
  22 #define XAPIAN_INCLUDED_MULTI_TERMLIST_H
  23
  24 #include "api/termlist.h"
  25
  26 #include <xapian/database.h>
  27
  28 using Xapian::Internal::intrusive_ptr_nonnull;
  29
  30 /** Adapter class for a TermList in a multidatabase.
  31  *
  32  *  Most methods just forward to @a real_termlist, but @a get_termfreq()
  33  *  fetches the combined term frequency from the multidatabase.
  34  */
  35 class MultiTermList : public TermList {
  36     /// Don't allow assignment.
  37     void operator=(const MultiTermList &) = delete;
  38
  39     /// Don't allow copying.
  40     MultiTermList(const MultiTermList &) = delete;
  41
  42     /// The TermList in the subdatabase.
  43     TermList* real_termlist;
  44
  45     /// The multidatabase.
  46     intrusive_ptr_nonnull<const Xapian::Database::Internal> db;
  47
  48   public:
  49     /// Constructor.
  50     MultiTermList(const Xapian::Database::Internal* db_, TermList* real_termlist_);
  51
  52     /// Destructor.
  53     ~MultiTermList();
  54
  55     /// Return approximate size of this termlist.
  56     Xapian::termcount get_approx_size() const;
  57
  58     /// Return the wdf for the term at the current position.
  59     Xapian::termcount get_wdf() const;
  60
  61     /// Return the term frequency for the term at the current position.
  62     Xapian::doccount get_termfreq() const;
  63
  64     /** Advance the current position to the next term in the termlist.
  65      *
  66      *  The list starts before the first term in the list, so next(), skip_to()
  67      *  or check() must be called before any methods which need the context of
  68      *  the current position.
  69      *
  70      *  @return If a non-NULL pointer is returned, then the caller should
  71      *          substitute the returned pointer for its pointer to us, and then
  72      *          delete us.  This "pruning" can only happen for a non-leaf
  73      *          subclass of this class.
  74      */
  75     Internal * next();
  76
  77     /** Skip forward to the specified term.
  78      *
  79      *  If the specified term isn't in the list, position ourselves on the
  80      *  first term after tname (or at_end() if no terms after tname exist).
  81      */
  82     Internal* skip_to(std::string_view term);
  83
  84     /// Return the length of the position list for the current position.
  85     Xapian::termcount positionlist_count() const;
  86
  87     /// Return a PositionIterator for the current position.
  88     PositionList* positionlist_begin() const;
  89 };
  90
  91 #endif // XAPIAN_INCLUDED_MULTI_TERMLIST_H