xapian-core/backends/alltermslist.h

   1 /** @file alltermslist.h
   2  * @brief Abstract base class for iterating all terms in a database.
   3  */
   4 /* Copyright (C) 2007,2008,2011 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (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_ALLTERMSLIST_H
  22 #define XAPIAN_INCLUDED_ALLTERMSLIST_H
  23
  24 #include "api/termlist.h"
  25
  26 /// Abstract base class for iterating all terms in a database.
  27 class AllTermsList : public TermList {
  28     /// Don't allow assignment.
  29     void operator=(const AllTermsList &);
  30
  31     /// Don't allow copying.
  32     AllTermsList(const AllTermsList &);
  33
  34   protected:
  35     /// Only constructable as a base class for derived classes.
  36     AllTermsList() { }
  37
  38   public:
  39     /// Return approximate size of this termlist.
  40     virtual Xapian::termcount get_approx_size() const = 0;
  41
  42     /// Return the termname at the current position.
  43     virtual std::string get_termname() const = 0;
  44
  45     /** Return the wdf for the term at the current position.
  46      *
  47      *  This isn't meaningful for an AllTermsList, and will throw
  48      *  Xapian::InvalidOperationError if called.
  49      */
  50     virtual Xapian::termcount get_wdf() const;
  51
  52     /// Return the term frequency for the term at the current position.
  53     virtual Xapian::doccount get_termfreq() const = 0;
  54
  55     /// Advance the current position to the next term in the termlist.
  56     virtual TermList *next() = 0;
  57
  58     /** Skip forward to the specified term.
  59      *
  60      *  If the specified term isn't in the list, position ourselves on the
  61      *  first term after @a term (or at_end() if no terms after @a term exist).
  62      */
  63     virtual TermList *skip_to(const std::string &term) = 0;
  64
  65     /// Return true if the current position is past the last term in this list.
  66     virtual bool at_end() const = 0;
  67
  68     /** Return true if the current position is past the last term in this list.
  69      *
  70      *  This isn't meaningful for an AllTermsList, and will throw
  71      *  Xapian::InvalidOperationError if called.
  72      */
  73     virtual Xapian::termcount positionlist_count() const;
  74
  75     /** Return a PositionIterator for the current position.
  76      *
  77      *  This isn't meaningful for an AllTermsList, and will throw
  78      *  Xapian::InvalidOperationError if called.
  79      */
  80     virtual PositionList* positionlist_begin() const;
  81 };
  82
  83 #endif // XAPIAN_INCLUDED_ALLTERMSLIST_H