xapian-core/matcher/queryoptimiser.h

   1 /** @file queryoptimiser.h
   2  * @brief Details passed around while building PostList tree from Query tree
   3  */
   4 /* Copyright (C) 2007,2008,2009,2010,2011,2013,2014,2015,2016 Olly Betts
   5  * Copyright (C) 2008 Lemur Consulting Ltd
   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 USA
  20  */
  21
  22 #ifndef XAPIAN_INCLUDED_QUERYOPTIMISER_H
  23 #define XAPIAN_INCLUDED_QUERYOPTIMISER_H
  24
  25 #include "backends/databaseinternal.h"
  26 #include "localsubmatch.h"
  27 #include "api/postlist.h"
  28
  29 class LeafPostList;
  30 class PostListTree;
  31
  32 class QueryOptimiser {
  33     /// Prevent assignment.
  34     void operator=(const QueryOptimiser &);
  35
  36     /// Prevent copying.
  37     QueryOptimiser(const QueryOptimiser &);
  38
  39     LocalSubMatch & localsubmatch;
  40
  41     /** How many weighted leaf subqueries there are.
  42      *
  43      *  Used for scaling percentages when the highest weighted document doesn't
  44      *  "match all terms".
  45      */
  46     Xapian::termcount total_subqs;
  47
  48     LeafPostList * hint;
  49
  50     bool hint_owned;
  51
  52   public:
  53     bool need_positions;
  54
  55     bool in_synonym;
  56
  57     bool full_db_has_positions;
  58
  59     const Xapian::Database::Internal & db;
  60
  61     Xapian::doccount db_size;
  62
  63     PostListTree * matcher;
  64
  65     QueryOptimiser(const Xapian::Database::Internal & db_,
  66                    LocalSubMatch & localsubmatch_,
  67                    PostListTree * matcher_,
  68                    bool full_db_has_positions_)
  69         : localsubmatch(localsubmatch_), total_subqs(0),
  70           hint(0), hint_owned(false),
  71           need_positions(false), in_synonym(false),
  72           full_db_has_positions(full_db_has_positions_),
  73           db(db_), db_size(db.get_doccount()),
  74           matcher(matcher_) { }
  75
  76     ~QueryOptimiser() {
  77         if (hint_owned) delete hint;
  78     }
  79
  80     void inc_total_subqs() { ++total_subqs; }
  81
  82     Xapian::termcount get_total_subqs() const { return total_subqs; }
  83
  84     void set_total_subqs(Xapian::termcount n) { total_subqs = n; }
  85
  86     PostList * open_post_list(const std::string& term,
  87                               Xapian::termcount wqf,
  88                               double factor) {
  89         return localsubmatch.open_post_list(term, wqf, factor, need_positions,
  90                                             in_synonym, this, false);
  91     }
  92
  93     PostList * open_lazy_post_list(const std::string& term,
  94                                    Xapian::termcount wqf,
  95                                    double factor) {
  96         return localsubmatch.open_post_list(term, wqf, factor, false,
  97                                             in_synonym, this, true);
  98     }
  99
 100     PostList * make_synonym_postlist(PostList * pl, double factor) {
 101         return localsubmatch.make_synonym_postlist(pl, factor);
 102     }
 103
 104     const LeafPostList * get_hint_postlist() const { return hint; }
 105
 106     void set_hint_postlist(LeafPostList * new_hint) {
 107         if (hint_owned) {
 108             hint_owned = false;
 109             delete hint;
 110         }
 111         hint = new_hint;
 112     }
 113
 114     void take_hint_ownership() { hint_owned = true; }
 115 };
 116
 117 #endif // XAPIAN_INCLUDED_QUERYOPTIMISER_H