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       1                 :            : /* mergepostlist.h: merge postlists from different databases
       2                 :            :  *
       3                 :            :  * Copyright 1999,2000,2001 BrightStation PLC
       4                 :            :  * Copyright 2002 Ananova Ltd
       5                 :            :  * Copyright 2002,2003,2004,2005,2009 Olly Betts
       6                 :            :  * Copyright 2007 Lemur Consulting Ltd
       7                 :            :  *
       8                 :            :  * This program is free software; you can redistribute it and/or
       9                 :            :  * modify it under the terms of the GNU General Public License as
      10                 :            :  * published by the Free Software Foundation; either version 2 of the
      11                 :            :  * License, or (at your option) any later version.
      12                 :            :  *
      13                 :            :  * This program is distributed in the hope that it will be useful,
      14                 :            :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      15                 :            :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      16                 :            :  * GNU General Public License for more details.
      17                 :            :  *
      18                 :            :  * You should have received a copy of the GNU General Public License
      19                 :            :  * along with this program; if not, write to the Free Software
      20                 :            :  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
      21                 :            :  * USA
      22                 :            :  */
      23                 :            : 
      24                 :            : #ifndef OM_HGUARD_MERGEPOSTLIST_H
      25                 :            : #define OM_HGUARD_MERGEPOSTLIST_H
      26                 :            : 
      27                 :            : #include "postlist.h"
      28                 :            : 
      29                 :            : class MultiMatch;
      30                 :            : class ValueStreamDocument;
      31                 :            : 
      32                 :            : /** A postlist comprising postlists from different databases merged together.
      33                 :            :  */
      34                 :            : class MergePostList : public PostList {
      35                 :            :     private:
      36                 :            :         // Prevent copying
      37                 :            :         MergePostList(const MergePostList &);
      38                 :            :         MergePostList & operator=(const MergePostList &);
      39                 :            : 
      40                 :            :         Xapian::weight w_max;
      41                 :            : 
      42                 :            :         vector<PostList *> plists;
      43                 :            : 
      44                 :            :         int current;
      45                 :            : 
      46                 :            :         /** The object which is using this postlist to perform
      47                 :            :          *  a match.  This object needs to be notified when the
      48                 :            :          *  tree changes such that the maximum weights need to be
      49                 :            :          *  recalculated.
      50                 :            :          */
      51                 :            :         MultiMatch *matcher;
      52                 :            : 
      53                 :            :         /** Document proxy used for valuestream caching.
      54                 :            :          *
      55                 :            :          *  We need to notify this when the subdatabase changes, as then the
      56                 :            :          *  cached valuestreams need to be cleared as they will be for the
      57                 :            :          *  wrong subdatabase.
      58                 :            :          */
      59                 :            :         ValueStreamDocument & vsdoc;
      60                 :            : 
      61                 :            :         Xapian::ErrorHandler * errorhandler;
      62                 :            :     public:
      63                 :            :         Xapian::termcount get_wdf() const;
      64                 :            :         Xapian::doccount get_termfreq_max() const;
      65                 :            :         Xapian::doccount get_termfreq_min() const;
      66                 :            :         Xapian::doccount get_termfreq_est() const;
      67                 :            : 
      68                 :            :         Xapian::docid  get_docid() const;
      69                 :            :         Xapian::weight get_weight() const;
      70                 :            :         const string * get_collapse_key() const;
      71                 :            : 
      72                 :            :         Xapian::weight get_maxweight() const;
      73                 :            : 
      74                 :            :         Xapian::weight recalc_maxweight();
      75                 :            : 
      76                 :            :         PostList *next(Xapian::weight w_min);
      77                 :            :         PostList *skip_to(Xapian::docid did, Xapian::weight w_min);
      78                 :            :         bool   at_end() const;
      79                 :            : 
      80                 :            :         string get_description() const;
      81                 :            : 
      82                 :            :         /** Return the document length of the document the current term
      83                 :            :          *  comes from.
      84                 :            :          */
      85                 :            :         virtual Xapian::termcount get_doclength() const;
      86                 :            : 
      87                 :            :         Xapian::termcount count_matching_subqs() const;
      88                 :            : 
      89                 :      71275 :         MergePostList(const std::vector<PostList *> & plists_,
      90                 :            :                       MultiMatch *matcher_,
      91                 :            :                       ValueStreamDocument & vsdoc_,
      92                 :            :                       Xapian::ErrorHandler * errorhandler_)
      93                 :            :             : plists(plists_), current(-1), matcher(matcher_), vsdoc(vsdoc_),
      94                 :      71275 :               errorhandler(errorhandler_) { }
      95                 :            : 
      96                 :            :         ~MergePostList();
      97                 :            : };
      98                 :            : 
      99                 :            : #endif /* OM_HGUARD_MERGEPOSTLIST_H */