xapian-core/common/submatch.h

   1 /** @file submatch.h
   2  *  @brief base class for sub-matchers
   3  */
   4 /* Copyright (C) 2006,2007,2009,2011,2014 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (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_SUBMATCH_H
  22 #define XAPIAN_INCLUDED_SUBMATCH_H
  23
  24 #include "xapian/intrusive_ptr.h"
  25 #include <xapian/types.h>
  26
  27 #include "api/postlist.h"
  28 #include "xapian/weight.h"
  29
  30 class PostListTree;
  31
  32 class SubMatch : public Xapian::Internal::intrusive_base {
  33   public:
  34     /** Virtual destructor.
  35      *
  36      *  Required because we have virtual methods and delete derived objects
  37      *  via a pointer to this base class.
  38      */
  39     virtual ~SubMatch() { }
  40
  41     /** Fetch and collate statistics.
  42      *
  43      *  Before we can calculate term weights we need to fetch statistics from
  44      *  each database involved and collate them.
  45      *
  46      *  @param nowait   A RemoteSubMatch may not be able to report statistics
  47      *                  when first asked.  If nowait is true, it will return
  48      *                  false in this situation allowing the matcher to ask
  49      *                  other database.  If nowait is false, then this method
  50      *                  will block until statistics are available.
  51      *
  52      *  @param total_stats A stats object to which the statistics should be
  53      *                  added.
  54      *
  55      *  @return         If nowait is true and results aren't available yet
  56      *                  then false will be returned and this method must be
  57      *                  called again before the match can proceed.  If results
  58      *                  are available or nowait is false, then this method
  59      *                  returns true.
  60      */
  61     virtual bool prepare_match(bool nowait,
  62                                Xapian::Weight::Internal & total_stats) = 0;
  63
  64     /** Start the match.
  65      *
  66      *  @param first          The first item in the result set to return.
  67      *  @param maxitems       The maximum number of items to return.
  68      *  @param check_at_least The minimum number of items to check.
  69      *  @param total_stats    The total statistics for the collection.
  70      */
  71     virtual void start_match(Xapian::doccount first,
  72                              Xapian::doccount maxitems,
  73                              Xapian::doccount check_at_least,
  74                              Xapian::Weight::Internal & total_stats) = 0;
  75
  76     /// Get PostList.
  77     virtual PostList * get_postlist(PostListTree *matcher,
  78                                     Xapian::termcount * total_subqs_ptr) = 0;
  79 };
  80
  81 #endif /* XAPIAN_INCLUDED_SUBMATCH_H */