xapian-core/include/xapian/expanddecider.h

   1 /** @file
   2  * @brief Allow rejection of terms during ESet generation.
   3  */
   4 /* Copyright (C) 2007,2011,2013,2014,2015,2016 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_EXPANDDECIDER_H
  22 #define XAPIAN_INCLUDED_EXPANDDECIDER_H
  23
  24 #if !defined XAPIAN_IN_XAPIAN_H && !defined XAPIAN_LIB_BUILD
  25 # error Never use <xapian/expanddecider.h> directly; include <xapian.h> instead.
  26 #endif
  27
  28 #include <set>
  29 #include <string>
  30
  31 #include <xapian/intrusive_ptr.h>
  32 #include <xapian/visibility.h>
  33
  34 namespace Xapian {
  35
  36 /** Virtual base class for expand decider functor. */
  37 class XAPIAN_VISIBILITY_DEFAULT ExpandDecider
  38     : public Xapian::Internal::opt_intrusive_base {
  39     /// Don't allow assignment.
  40     void operator=(const ExpandDecider &) = delete;
  41
  42     /// Don't allow copying.
  43     ExpandDecider(const ExpandDecider &) = delete;
  44
  45   public:
  46     /// Default constructor.
  47     ExpandDecider() { }
  48
  49     /** Do we want this term in the ESet?
  50      *
  51      *  @param term     The term to test.
  52      */
  53     virtual bool operator()(const std::string &term) const = 0;
  54
  55     /** Virtual destructor, because we have virtual methods. */
  56     virtual ~ExpandDecider();
  57
  58     /** Start reference counting this object.
  59      *
  60      *  You can transfer ownership of a dynamically allocated ExpandDecider
  61      *  object to Xapian by calling release() and then passing the object to a
  62      *  Xapian method.  Xapian will arrange to delete the object once it is no
  63      *  longer required.
  64      */
  65     ExpandDecider * release() {
  66         opt_intrusive_base::release();
  67         return this;
  68     }
  69
  70     /** Start reference counting this object.
  71      *
  72      *  You can transfer ownership of a dynamically allocated ExpandDecider
  73      *  object to Xapian by calling release() and then passing the object to a
  74      *  Xapian method.  Xapian will arrange to delete the object once it is no
  75      *  longer required.
  76      */
  77     const ExpandDecider * release() const {
  78         opt_intrusive_base::release();
  79         return this;
  80     }
  81 };
  82
  83 /** ExpandDecider subclass which rejects terms using two ExpandDeciders.
  84  *
  85  *  Terms are only accepted if they are accepted by both of the specified
  86  *  ExpandDecider objects.
  87  */
  88 class XAPIAN_VISIBILITY_DEFAULT ExpandDeciderAnd : public ExpandDecider {
  89     Internal::opt_intrusive_ptr<const ExpandDecider> first, second;
  90
  91   public:
  92     /** Terms will be checked with @a first, and if accepted, then checked
  93      *  with @a second.
  94      *
  95      *  @param first_   First ExpandDecider object to test with.
  96      *  @param second_  ExpandDecider object to test with if first_ accepts.
  97      */
  98     ExpandDeciderAnd(const ExpandDecider &first_,
  99                      const ExpandDecider &second_)
 100         : first(&first_), second(&second_) { }
 101
 102     /** Compatibility method.
 103      *
 104      *  @param first_   First ExpandDecider object to test with.
 105      *  @param second_  ExpandDecider object to test with if first_ accepts.
 106      */
 107     ExpandDeciderAnd(const ExpandDecider *first_,
 108                      const ExpandDecider *second_)
 109         : first(first_), second(second_) { }
 110
 111     virtual bool operator()(const std::string &term) const;
 112 };
 113
 114 /** ExpandDecider subclass which rejects terms in a specified list.
 115  *
 116  *  ExpandDeciderFilterTerms provides an easy way to filter out terms from
 117  *  a fixed list when generating an ESet.
 118  */
 119 class XAPIAN_VISIBILITY_DEFAULT ExpandDeciderFilterTerms : public ExpandDecider {
 120     std::set<std::string> rejects;
 121
 122   public:
 123     /** The two iterators specify a list of terms to be rejected.
 124      *
 125      *  @param reject_begin     Begin iterator for the list of terms to
 126      *                          reject.  It can be any input_iterator type
 127      *                          which returns std::string or char * (e.g.
 128      *                          TermIterator or char **).
 129      *  @param reject_end       End iterator for the list of terms to reject.
 130      */
 131     template<class Iterator>
 132     ExpandDeciderFilterTerms(Iterator reject_begin, Iterator reject_end)
 133         : rejects(reject_begin, reject_end) { }
 134
 135     virtual bool operator()(const std::string &term) const;
 136 };
 137
 138 /** ExpandDecider subclass which restrict terms to a particular prefix
 139  *
 140  *  ExpandDeciderFilterPrefix provides an easy way to choose terms with a
 141  *  particular prefix when generating an ESet.
 142  */
 143 class XAPIAN_VISIBILITY_DEFAULT ExpandDeciderFilterPrefix : public ExpandDecider {
 144     std::string prefix;
 145
 146   public:
 147     /** The parameter specify the prefix of terms to be retained
 148      *  @param prefix_   restrict terms to the particular prefix_
 149      */
 150     explicit ExpandDeciderFilterPrefix(const std::string &prefix_)
 151         : prefix(prefix_) { }
 152
 153     virtual bool operator() (const std::string &term) const;
 154 };
 155
 156 }
 157
 158 #endif // XAPIAN_INCLUDED_EXPANDDECIDER_H