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 namespace Xapian {
  33 namespace Internal {
  34
  35 class QueryOptimiser {
  36     /// Prevent assignment.
  37     void operator=(const QueryOptimiser &);
  38
  39     /// Prevent copying.
  40     QueryOptimiser(const QueryOptimiser &);
  41
  42     LocalSubMatch & localsubmatch;
  43
  44     /** How many weighted leaf subqueries there are.
  45      *
  46      *  Used for scaling percentages when the highest weighted document doesn't
  47      *  "match all terms".
  48      */
  49     Xapian::termcount total_subqs;
  50
  51     LeafPostList * hint;
  52
  53     bool hint_owned;
  54
  55   public:
  56     bool need_positions;
  57
  58     bool in_synonym;
  59
  60     bool full_db_has_positions;
  61
  62     const Xapian::Database::Internal & db;
  63
  64     Xapian::doccount db_size;
  65
  66     PostListTree * matcher;
  67
  68     QueryOptimiser(const Xapian::Database::Internal & db_,
  69                    LocalSubMatch & localsubmatch_,
  70                    PostListTree * matcher_,
  71                    bool full_db_has_positions_)
  72         : localsubmatch(localsubmatch_), total_subqs(0),
  73           hint(0), hint_owned(false),
  74           need_positions(false), in_synonym(false),
  75           full_db_has_positions(full_db_has_positions_),
  76           db(db_), db_size(db.get_doccount()),
  77           matcher(matcher_) { }
  78
  79     ~QueryOptimiser() {
  80         if (hint_owned) delete hint;
  81     }
  82
  83     void inc_total_subqs() { ++total_subqs; }
  84
  85     Xapian::termcount get_total_subqs() const { return total_subqs; }
  86
  87     void set_total_subqs(Xapian::termcount n) { total_subqs = n; }
  88
  89     PostList * open_post_list(const std::string& term,
  90                               Xapian::termcount wqf,
  91                               double factor) {
  92         return localsubmatch.open_post_list(term, wqf, factor, need_positions,
  93                                             in_synonym, this, false);
  94     }
  95
  96     PostList * open_lazy_post_list(const std::string& term,
  97                                    Xapian::termcount wqf,
  98                                    double factor) {
  99         return localsubmatch.open_post_list(term, wqf, factor, need_positions,
 100                                             in_synonym, this, true);
 101     }
 102
 103     PostList * make_synonym_postlist(PostList * pl, double factor) {
 104         return localsubmatch.make_synonym_postlist(matcher, pl, factor);
 105     }
 106
 107     const LeafPostList * get_hint_postlist() const { return hint; }
 108
 109     void set_hint_postlist(LeafPostList * new_hint) {
 110         if (hint_owned) {
 111             hint_owned = false;
 112             delete hint;
 113         }
 114         hint = new_hint;
 115     }
 116
 117     void take_hint_ownership() { hint_owned = true; }
 118 };
 119
 120 }
 121 }
 122
 123 using Xapian::Internal::QueryOptimiser;
 124
 125 #endif // XAPIAN_INCLUDED_QUERYOPTIMISER_H