xapian-core/matcher/selectpostlist.h

   1 /** @file
   2  * @brief Base class for classes which filter another PostList
   3  */
   4 /* Copyright 2017-2022 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_SELECTPOSTLIST_H
  22 #define XAPIAN_INCLUDED_SELECTPOSTLIST_H
  23
  24 #include "wrapperpostlist.h"
  25
  26 #include <cmath>
  27
  28 class EstimateOp;
  29 class PostListTree;
  30
  31 /// Base class for classes which filter another PostList
  32 class SelectPostList : public WrapperPostList {
  33     /// Used to avoid calculating the weight twice for a given document.
  34     double cached_weight = -HUGE_VAL;
  35
  36     PostListTree* pltree;
  37
  38     /// Check if the current document is suitable.
  39     bool vet(double w_min);
  40
  41   protected:
  42     /// Number of times test_doc() returned true.
  43     Xapian::doccount accepted = 0;
  44
  45     /// Number of times test_doc() returned false.
  46     Xapian::doccount rejected = 0;
  47
  48     /// Object to report accepted/rejected counts to.
  49     EstimateOp* estimate_op;
  50
  51     /// Check if the current document should be selected.
  52     virtual bool test_doc() = 0;
  53
  54   public:
  55     SelectPostList(PostList* pl_,
  56                    EstimateOp* estimate_op_,
  57                    PostListTree* pltree_)
  58         : WrapperPostList(pl_), pltree(pltree_), estimate_op(estimate_op_) {}
  59
  60     ~SelectPostList();
  61
  62     double get_weight(Xapian::termcount doclen,
  63                       Xapian::termcount unique_terms,
  64                       Xapian::termcount wdfdocmax) const;
  65
  66     bool at_end() const;
  67
  68     PostList* next(double w_min);
  69
  70     PostList* skip_to(Xapian::docid did, double w_min);
  71
  72     PostList* check(Xapian::docid did, double w_min, bool& valid);
  73 };
  74
  75 #endif // XAPIAN_INCLUDED_SELECTPOSTLIST_H