xapian-core/backends/glass/glass_metadata.h

   1 /** @file glass_metadata.h
   2  * @brief Access to metadata for a glass database.
   3  */
   4 /* Copyright (C) 2005,2007,2008,2009,2011,2017 Olly Betts
   5  * Copyright (C) 2008 Lemur Consulting Ltd
   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_GLASS_METADATA_H
  23 #define XAPIAN_INCLUDED_GLASS_METADATA_H
  24
  25 #include <xapian/intrusive_ptr.h>
  26 #include <xapian/database.h>
  27 #include <xapian/types.h>
  28
  29 #include "backends/alltermslist.h"
  30 #include "glass_table.h"
  31 #include "api/termlist.h"
  32
  33 #include <string>
  34
  35 class GlassCursor;
  36
  37 class GlassMetadataTermList : public AllTermsList {
  38     /// Copying is not allowed.
  39     GlassMetadataTermList(const GlassMetadataTermList &);
  40
  41     /// Assignment is not allowed.
  42     void operator=(const GlassMetadataTermList &);
  43
  44     /// Keep a reference to our database to stop it being deleted.
  45     Xapian::Internal::intrusive_ptr<const Xapian::Database::Internal> database;
  46
  47     /** A cursor which runs through the postlist table reading metadata keys.
  48      */
  49     GlassCursor * cursor;
  50
  51     /** The prefix that all returned keys must have.
  52      */
  53     std::string prefix;
  54
  55   public:
  56     GlassMetadataTermList(Xapian::Internal::intrusive_ptr<const Xapian::Database::Internal> database_,
  57                           GlassCursor * cursor_, const std::string &prefix_);
  58
  59     ~GlassMetadataTermList();
  60
  61     Xapian::termcount get_approx_size() const;
  62
  63     /** Returns the current termname.
  64      *
  65      *  Either next() or skip_to() must have been called before this
  66      *  method can be called.
  67      */
  68     std::string get_termname() const;
  69
  70     /** Return the term frequency for the term at the current position.
  71      *
  72      *  Not meaningful for a GlassMetadataTermList.
  73      */
  74     Xapian::doccount get_termfreq() const;
  75
  76     /** Return the collection frequency for the term at the current position.
  77      *
  78      *  Not meaningful for a GlassMetadataTermList.
  79      */
  80     Xapian::termcount get_collection_freq() const;
  81
  82     /// Advance to the next term in the list.
  83     TermList * next();
  84
  85     /// Advance to the first key which is >= @a key.
  86     TermList * skip_to(const std::string &key);
  87
  88     /// True if we're off the end of the list
  89     bool at_end() const;
  90 };
  91
  92 #endif // XAPIAN_INCLUDED_GLASS_METADATA_H