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       1                 :            : /* orpostlist.h: OR of two posting lists
       2                 :            :  *
       3                 :            :  * Copyright 1999,2000,2001 BrightStation PLC
       4                 :            :  * Copyright 2002 Ananova Ltd
       5                 :            :  * Copyright 2003,2004,2009,2010 Olly Betts
       6                 :            :  * Copyright 2009 Lemur Consulting Ltd
       7                 :            :  * Copyright 2010 Richard Boulton
       8                 :            :  *
       9                 :            :  * This program is free software; you can redistribute it and/or
      10                 :            :  * modify it under the terms of the GNU General Public License as
      11                 :            :  * published by the Free Software Foundation; either version 2 of the
      12                 :            :  * License, or (at your option) any later version.
      13                 :            :  *
      14                 :            :  * This program is distributed in the hope that it will be useful,
      15                 :            :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      16                 :            :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      17                 :            :  * GNU General Public License for more details.
      18                 :            :  *
      19                 :            :  * You should have received a copy of the GNU General Public License
      20                 :            :  * along with this program; if not, write to the Free Software
      21                 :            :  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
      22                 :            :  * USA
      23                 :            :  */
      24                 :            : 
      25                 :            : #ifndef OM_HGUARD_ORPOSTLIST_H
      26                 :            : #define OM_HGUARD_ORPOSTLIST_H
      27                 :            : 
      28                 :            : #include "branchpostlist.h"
      29                 :            : 
      30                 :            : /** A postlist comprising two postlists ORed together.
      31                 :            :  *
      32                 :            :  *  This postlist returns a posting if it is in either of the sub-postlists.
      33                 :            :  *  The weight for a posting is the sum of the weights of the sub-postings,
      34                 :            :  *  if both exist, or the sum of the single sub-posting which exists
      35                 :            :  *  otherwise.
      36                 :            :  */
      37 [ +  - ][ #  # ]:     234094 : class OrPostList : public BranchPostList {
      38                 :            :     private:
      39                 :            :         Xapian::docid lhead, rhead;
      40                 :            :         bool lvalid, rvalid;
      41                 :            :         Xapian::weight lmax, rmax, minmax;
      42                 :            :         Xapian::doccount dbsize;
      43                 :            :     public:
      44                 :            :         Xapian::doccount get_termfreq_max() const;
      45                 :            :         Xapian::doccount get_termfreq_min() const;
      46                 :            :         Xapian::doccount get_termfreq_est() const;
      47                 :            :         TermFreqs get_termfreq_est_using_stats(
      48                 :            :             const Xapian::Weight::Internal & stats) const;
      49                 :            : 
      50                 :            :         Xapian::docid  get_docid() const;
      51                 :            :         Xapian::weight get_weight() const;
      52                 :            :         Xapian::weight get_maxweight() const;
      53                 :            : 
      54                 :            :         Xapian::weight recalc_maxweight();
      55                 :            : 
      56                 :            :         PostList *next(Xapian::weight w_min);
      57                 :            :         PostList *skip_to(Xapian::docid did, Xapian::weight w_min);
      58                 :            :         PostList *check(Xapian::docid did, Xapian::weight w_min, bool &valid);
      59                 :            :         bool   at_end() const;
      60                 :            : 
      61                 :            :         std::string get_description() const;
      62                 :            : 
      63                 :            :         /** Return the document length of the document the current term
      64                 :            :          *  comes from.
      65                 :            :          *
      66                 :            :          *  This is obtained by asking the subpostlist which contains the
      67                 :            :          *  current document for the document length.  If both subpostlists
      68                 :            :          *  are valid, the left one is asked.
      69                 :            :          */
      70                 :            :         virtual Xapian::termcount get_doclength() const;
      71                 :            : 
      72                 :            :         OrPostList(PostList * left_,
      73                 :            :                    PostList * right_,
      74                 :            :                    MultiMatch * matcher_,
      75                 :            :                    Xapian::doccount dbsize_);
      76                 :            : 
      77                 :            :         /** get_wdf() for OR postlists returns the sum of the wdfs of the
      78                 :            :          *  sub postlists which are at the current document - this is desirable
      79                 :            :          *  when the OR is part of a synonym.
      80                 :            :          */
      81                 :            :         Xapian::termcount get_wdf() const;
      82                 :            : 
      83                 :            :         Xapian::termcount count_matching_subqs() const;
      84                 :            : };
      85                 :            : 
      86                 :            : #endif /* OM_HGUARD_ORPOSTLIST_H */