xapian-core/expand/esetinternal.h

   1 /** @file
   2  * @brief Xapian::ESet::Internal class
   3  */
   4 /* Copyright (C) 2008,2010,2011 Olly Betts
   5  * Copyright (C) 2011 Action Without Borders
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (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_ESETINTERNAL_H
  23 #define XAPIAN_INCLUDED_ESETINTERNAL_H
  24
  25 #include "xapian/intrusive_ptr.h"
  26 #include "xapian/enquire.h"
  27 #include "xapian/eset.h"
  28 #include "xapian/types.h"
  29
  30 #include <algorithm>
  31 #include <string>
  32 #include <vector>
  33
  34 namespace Xapian {
  35     class Database;
  36     class ExpandDecider;
  37
  38     namespace Internal {
  39         class ExpandWeight;
  40
  41 /// Class combining a term and its expand weight.
  42 class ExpandTerm {
  43     friend class Xapian::ESet::Internal;
  44
  45     /// The expand weight calculated for this term.
  46     double wt;
  47
  48     /// The term.
  49     std::string term;
  50
  51   public:
  52     /// Constructor.
  53     ExpandTerm(double wt_, const std::string & term_)
  54         : wt(wt_), term(term_) { }
  55
  56     /// Implement custom swap for ESet sorting efficiency.
  57     void swap(ExpandTerm & o) {
  58         std::swap(wt, o.wt);
  59         std::swap(term, o.term);
  60     }
  61
  62     /// Ordering relation for ESet contents.
  63     bool operator<(const ExpandTerm & o) const {
  64         if (wt > o.wt) return true;
  65         if (wt < o.wt) return false;
  66         return term > o.term;
  67     }
  68
  69     std::string get_term() const { return term; }
  70
  71     double get_weight() const { return wt; }
  72
  73     /// Return a string describing this object.
  74     std::string get_description() const;
  75 };
  76
  77 }
  78
  79 /// Class which actually implements Xapian::ESet.
  80 class ESet::Internal : public Xapian::Internal::intrusive_base {
  81     friend class ESet;
  82     friend class ESetIterator;
  83
  84     /** This is a lower bound on the ESet size if an infinite number of results
  85      *  were requested.
  86      *
  87      *  It will of course always be true that: ebound >= items.size()
  88      */
  89     Xapian::termcount ebound = 0;
  90
  91     /// The ExpandTerm objects which represent the items in the ESet.
  92     std::vector<Xapian::Internal::ExpandTerm> items;
  93
  94     /// Don't allow assignment.
  95     void operator=(const Internal &);
  96
  97     /// Don't allow copying.
  98     Internal(const Internal &);
  99
 100   public:
 101     /// Construct an empty ESet::Internal.
 102     Internal() { }
 103
 104     /// Run the "expand" operation which fills the ESet.
 105     void expand(Xapian::termcount max_esize,
 106                 const Xapian::Database & db,
 107                 const Xapian::RSet & rset,
 108                 const Xapian::ExpandDecider * edecider,
 109                 Xapian::Internal::ExpandWeight & eweight,
 110                 double min_wt);
 111
 112     /// Return a string describing this object.
 113     std::string get_description() const;
 114 };
 115
 116 }
 117
 118 #endif // XAPIAN_INCLUDED_ESETINTERNAL_H