xapian-core/matcher/postlisttree.h

   1 /** @file postlisttree.h
   2  * @brief Class for managing a tree of PostList objects
   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_POSTLISTTREE_H
  22 #define XAPIAN_INCLUDED_POSTLISTTREE_H
  23
  24 #include "api/postlist.h"
  25
  26 class PostListTree {
  27     PostList* pl = NULL;
  28
  29     bool use_cached_max_weight = false;
  30
  31     double max_weight;
  32
  33   public:
  34     PostListTree() {}
  35
  36     ~PostListTree() {
  37         delete pl;
  38     }
  39
  40     void set_postlist(PostList* pl_) {
  41         pl = pl_;
  42     }
  43
  44     double recalc_maxweight() {
  45         if (!use_cached_max_weight) {
  46             use_cached_max_weight = true;
  47             max_weight = pl->recalc_maxweight();
  48         }
  49         return max_weight;
  50     }
  51
  52     void force_recalc() {
  53         use_cached_max_weight = false;
  54     }
  55
  56     Xapian::doccount get_termfreq_min() const {
  57         return pl->get_termfreq_min();
  58     }
  59
  60     Xapian::doccount get_termfreq_max() const {
  61         return pl->get_termfreq_max();
  62     }
  63
  64     Xapian::doccount get_termfreq_est() const {
  65         return pl->get_termfreq_est();
  66     }
  67
  68     Xapian::docid get_docid() const {
  69         return pl->get_docid();
  70     }
  71
  72     double get_weight() const {
  73         return pl->get_weight();
  74     }
  75
  76     const std::string* get_sort_key() const {
  77         return pl->get_sort_key();
  78     }
  79
  80     const std::string* get_collapse_key() const {
  81         return pl->get_collapse_key();
  82     }
  83
  84     /// Return false if we're done.
  85     bool next(double w_min) {
  86         if (rare(!use_cached_max_weight) && w_min > 0.0) {
  87             if (recalc_maxweight() < w_min) {
  88                 // We can't now achieve w_min so we're done.
  89                 return false;
  90             }
  91         }
  92
  93         PostList* result = pl->next(w_min);
  94         if (rare(result)) {
  95             delete pl;
  96             pl = result;
  97         }
  98         if (rare(pl->at_end()))
  99             return false;
 100
 101         if (rare(result) && w_min > 0.0) {
 102             use_cached_max_weight = false;
 103             if (recalc_maxweight() < w_min) {
 104                 // We can't now achieve w_min so we're done.
 105                 return false;
 106             }
 107         }
 108
 109         return true;
 110     }
 111
 112     Xapian::termcount count_matching_subqs() const {
 113         return pl->count_matching_subqs();
 114     }
 115
 116     std::string get_description() const {
 117         return pl->get_description();
 118     }
 119 };
 120
 121 #endif // XAPIAN_INCLUDED_POSTLISTTREE_H