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       1                 :            : /* andnotpostlist.h: Return items which are in A, unless they're in B
       2                 :            :  *
       3                 :            :  * Copyright 1999,2000,2001 BrightStation PLC
       4                 :            :  * Copyright 2002 Ananova Ltd
       5                 :            :  * Copyright 2003,2004,2009 Olly Betts
       6                 :            :  * Copyright 2009 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_ANDNOTPOSTLIST_H
      25                 :            : #define OM_HGUARD_ANDNOTPOSTLIST_H
      26                 :            : 
      27                 :            : #include "branchpostlist.h"
      28                 :            : 
      29                 :            : /** A postlist generated by taking one postlist (the left-hand postlist),
      30                 :            :  *  and removing any documents which are in the other (right-hand) postlist.
      31                 :            :  *
      32                 :            :  *  The weight for a posting is the weight in the left-hand postlist.
      33                 :            :  */
      34 [ +  - ][ #  # ]:        128 : class AndNotPostList : public BranchPostList {
      35                 :            :     private:
      36                 :            :         Xapian::docid lhead, rhead;
      37                 :            : 
      38                 :            :         /// Number of documents in the database this postlist is across
      39                 :            :         Xapian::doccount dbsize;
      40                 :            : 
      41                 :            :         PostList *advance_to_next_match(Xapian::weight w_min, PostList *ret);
      42                 :            :     public:
      43                 :            :         Xapian::doccount get_termfreq_max() const;
      44                 :            :         Xapian::doccount get_termfreq_min() const;
      45                 :            :         Xapian::doccount get_termfreq_est() const;
      46                 :            :         TermFreqs get_termfreq_est_using_stats(
      47                 :            :             const Xapian::Weight::Internal & stats) const;
      48                 :            : 
      49                 :            :         Xapian::docid  get_docid() const;
      50                 :            :         Xapian::weight get_weight() const;
      51                 :            :         Xapian::weight get_maxweight() const;
      52                 :            : 
      53                 :            :         Xapian::weight recalc_maxweight();
      54                 :            : 
      55                 :            :         PostList *next(Xapian::weight w_min);
      56                 :            :         PostList *skip_to(Xapian::docid did, Xapian::weight w_min);
      57                 :            :         bool   at_end() const;
      58                 :            : 
      59                 :            :         std::string get_description() const;
      60                 :            : 
      61                 :            :         /** Return the document length of the document the current term
      62                 :            :          *  comes from.
      63                 :            :          */
      64                 :            :         virtual Xapian::termcount get_doclength() const;
      65                 :            : 
      66                 :            :         AndNotPostList(PostList *left,
      67                 :            :                        PostList *right,
      68                 :            :                        MultiMatch *matcher_,
      69                 :            :                        Xapian::doccount dbsize_);
      70                 :            : 
      71                 :            :         PostList *sync_and_skip_to(Xapian::docid id,
      72                 :            :                                    Xapian::weight w_min,
      73                 :            :                                    Xapian::docid lh,
      74                 :            :                                    Xapian::docid rh);
      75                 :            : 
      76                 :            :         /** get_wdf() for ANDNOT postlists returns the wdf of the left hand
      77                 :            :          * side.
      78                 :            :          */
      79                 :            :         Xapian::termcount get_wdf() const;
      80                 :            : 
      81                 :            :         Xapian::termcount count_matching_subqs() const;
      82                 :            : };
      83                 :            : 
      84                 :            : #endif /* OM_HGUARD_ANDNOTPOSTLIST_H */