xapian-core/matcher/andmaybepostlist.h

   1 /** @file andmaybepostlist.h
   2  * @brief PostList class implementing Query::OP_AND_MAYBE
   3  */
   4 /* Copyright 2017 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_ANDMAYBEPOSTLIST_H
  22 #define XAPIAN_INCLUDED_ANDMAYBEPOSTLIST_H
  23
  24 #include "postlisttree.h"
  25 #include "wrapperpostlist.h"
  26
  27 /// PostList class implementing Query::OP_AND_MAYBE
  28 class AndMaybePostList : public WrapperPostList {
  29     /// Right-hand side of OP_MAYBE.
  30     PostList* r;
  31
  32     /// Current docid from WrapperPostList's pl.
  33     Xapian::docid pl_did = 0;
  34
  35     /// Current docid from @a r (or 0).
  36     Xapian::docid r_did = 0;
  37
  38     /// Current max weight from WrapperPostList's pl.
  39     double pl_max;
  40
  41     /// Current max weight from @a r.
  42     double r_max;
  43
  44     /** Total number of documents in the database.
  45      *
  46      *  Only used if we decay to AND.
  47      */
  48     Xapian::doccount db_size;
  49
  50     PostListTree* pltree;
  51
  52     /// Does @a r match at the current position?
  53     bool maybe_matches() const { return pl_did == r_did; }
  54
  55     PostList* decay_to_and(Xapian::docid did,
  56                            double w_min,
  57                            bool* valid_ptr = NULL);
  58
  59   public:
  60     AndMaybePostList(PostList* left, PostList* right,
  61                      PostListTree* pltree_, Xapian::doccount db_size_)
  62         : WrapperPostList(left), r(right), db_size(db_size_), pltree(pltree_)
  63     {}
  64
  65     /** Construct as decay product from OrPostList.
  66      *
  67      *  The first operation after such construction must be check() or
  68      *  skip_to().
  69      */
  70     AndMaybePostList(PostList* left,
  71                      PostList* right,
  72                      double lmax,
  73                      double rmax,
  74                      PostListTree* pltree_,
  75                      Xapian::doccount db_size_)
  76         : WrapperPostList(left), r(right), pl_max(lmax), r_max(rmax),
  77           db_size(db_size_), pltree(pltree_)
  78     {
  79     }
  80
  81     ~AndMaybePostList() { delete r; }
  82
  83     Xapian::docid get_docid() const;
  84
  85     double get_weight(Xapian::termcount doclen,
  86                       Xapian::termcount unique_terms) const;
  87
  88     double recalc_maxweight();
  89
  90     PostList* next(double w_min);
  91
  92     PostList* skip_to(Xapian::docid did, double w_min);
  93
  94     PostList* check(Xapian::docid did, double w_min, bool& valid);
  95
  96     std::string get_description() const;
  97
  98     Xapian::termcount get_wdf() const;
  99
 100     Xapian::termcount count_matching_subqs() const;
 101
 102     void gather_position_lists(OrPositionList* orposlist);
 103 };
 104
 105 #endif // XAPIAN_INCLUDED_ANDMAYBEPOSTLIST_H