xapian-core/matcher/selectpostlist.h

   1 /** @file
   2  * @brief Parent class for classes which only return selected docs
   3  */
   4 /* Copyright 1999,2000,2001 BrightStation PLC
   5  * Copyright 2003,2004,2009,2010,2011,2012,2013 Olly Betts
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as
   9  * published by the Free Software Foundation; either version 2 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
  20  * USA
  21  */
  22
  23 #ifndef OM_HGUARD_SELECTPOSTLIST_H
  24 #define OM_HGUARD_SELECTPOSTLIST_H
  25
  26 #include "api/postlist.h"
  27
  28 /** A postlist parent class for classes which only return selected docs
  29  *  from a source postlist (e.g. NEAR and PHRASE)
  30  */
  31 class SelectPostList : public PostList {
  32     private:
  33         // Prevent copying
  34         SelectPostList(const SelectPostList &);
  35         SelectPostList & operator=(const SelectPostList &);
  36
  37         inline bool check_weight(double w_min) {
  38             return w_min == 0.0 || SelectPostList::get_weight() >= w_min;
  39         }
  40
  41     protected:
  42         PostList *source;
  43         mutable double wt;
  44
  45         /** Subclasses should override test_doc() with a method which returns
  46          *  true if a document meets the appropriate criterion, false in not
  47          */
  48         virtual bool test_doc() = 0;
  49     public:
  50         PostList *next(double w_min);
  51         PostList *skip_to(Xapian::docid did, double w_min);
  52         PostList *check(Xapian::docid did, double w_min, bool &valid);
  53
  54         // pass all these through to the underlying source PostList
  55         Xapian::doccount get_termfreq_max() const { return source->get_termfreq_max(); }
  56         Xapian::doccount get_termfreq_min() const { return 0; }
  57         double get_maxweight() const { return source->get_maxweight(); }
  58         Xapian::docid get_docid() const { return source->get_docid(); }
  59         double get_weight() const {
  60             if (wt < 0.0)
  61                 wt = source->get_weight();
  62             return wt;
  63         }
  64         Xapian::termcount get_doclength() const { return source->get_doclength(); }
  65         Xapian::termcount get_unique_terms() const { return source->get_unique_terms(); }
  66         double recalc_maxweight() { return source->recalc_maxweight(); }
  67         PositionList * read_position_list() { return source->read_position_list(); }
  68         PositionList * open_position_list() const { return source->open_position_list(); }
  69         bool at_end() const { return source->at_end(); }
  70
  71         Xapian::termcount count_matching_subqs() const {
  72             return source->count_matching_subqs();
  73         }
  74
  75         std::string get_description() const;
  76
  77         explicit SelectPostList(PostList *source_) : source(source_), wt(-1) { }
  78         ~SelectPostList() { delete source; }
  79 };
  80
  81 inline std::string
  82 SelectPostList::get_description() const
  83 {
  84     return "(Select " + source->get_description() + ")";
  85 }
  86
  87 #endif /* OM_HGUARD_SELECTPOSTLIST_H */