xapian-core/backends/glass/glass_metadata.cc

   1 /** @file glass_metadata.cc
   2  * @brief Access to metadata for a glass database.
   3  */
   4 /* Copyright (C) 2004,2005,2006,2007,2008,2009,2010,2011,2017 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 #include <config.h>
  23
  24 #include "glass_metadata.h"
  25
  26 #include "glass_cursor.h"
  27
  28 #include "backends/databaseinternal.h"
  29 #include "debuglog.h"
  30 #include "omassert.h"
  31 #include "stringutils.h"
  32
  33 #include "xapian/error.h"
  34
  35 using namespace std;
  36 using Xapian::Internal::intrusive_ptr;
  37
  38 GlassMetadataTermList::GlassMetadataTermList(
  39         intrusive_ptr<const Xapian::Database::Internal> database_,
  40         GlassCursor * cursor_,
  41         const string &prefix_)
  42         : database(database_), cursor(cursor_), prefix(string("\x00\xc0", 2) + prefix_)
  43 {
  44     LOGCALL_CTOR(DB, "GlassMetadataTermList", database_ | cursor_ | prefix_);
  45     Assert(cursor);
  46     // Seek to the first key before the first metadata key.
  47     cursor->find_entry_lt(prefix);
  48 }
  49
  50 GlassMetadataTermList::~GlassMetadataTermList()
  51 {
  52     LOGCALL_DTOR(DB, "GlassMetadataTermList");
  53     delete cursor;
  54 }
  55
  56 Xapian::termcount
  57 GlassMetadataTermList::get_approx_size() const
  58 {
  59     // Very approximate!  This is only used to build a balanced or tree, so
  60     // at least we'll get an even tree by returning a constant answer.
  61     return 1;
  62 }
  63
  64 string
  65 GlassMetadataTermList::get_termname() const
  66 {
  67     LOGCALL(DB, string, "GlassMetadataTermList::get_termname", NO_ARGS);
  68     Assert(!at_end());
  69     Assert(!cursor->current_key.empty());
  70     Assert(startswith(cursor->current_key, prefix));
  71     RETURN(cursor->current_key.substr(2));
  72 }
  73
  74 Xapian::doccount
  75 GlassMetadataTermList::get_termfreq() const
  76 {
  77     throw Xapian::InvalidOperationError("GlassMetadataTermList::get_termfreq() not meaningful");
  78 }
  79
  80 Xapian::termcount
  81 GlassMetadataTermList::get_collection_freq() const
  82 {
  83     throw Xapian::InvalidOperationError("GlassMetadataTermList::get_collection_freq() not meaningful");
  84 }
  85
  86 TermList *
  87 GlassMetadataTermList::next()
  88 {
  89     LOGCALL(DB, TermList *, "GlassMetadataTermList::next", NO_ARGS);
  90     Assert(!at_end());
  91
  92     cursor->next();
  93     if (!cursor->after_end() && !startswith(cursor->current_key, prefix)) {
  94         // We've reached the end of the prefixed terms.
  95         cursor->to_end();
  96     }
  97
  98     RETURN(NULL);
  99 }
 100
 101 TermList *
 102 GlassMetadataTermList::skip_to(const string &key)
 103 {
 104     LOGCALL(DB, TermList *, "GlassMetadataTermList::skip_to", key);
 105     Assert(!at_end());
 106
 107     if (!cursor->find_entry_ge(string("\x00\xc0", 2) + key)) {
 108         // The exact term we asked for isn't there, so check if the next
 109         // term after it also has the right prefix.
 110         if (!cursor->after_end() && !startswith(cursor->current_key, prefix)) {
 111             // We've reached the end of the prefixed terms.
 112             cursor->to_end();
 113         }
 114     }
 115     RETURN(NULL);
 116 }
 117
 118 bool
 119 GlassMetadataTermList::at_end() const
 120 {
 121     LOGCALL(DB, bool, "GlassMetadataTermList::at_end", NO_ARGS);
 122     RETURN(cursor->after_end());
 123 }