xapian-core/backends/glass/glass_inverter.h

   1 /** @file glass_inverter.h
   2  * @brief Inverter class which "inverts the file".
   3  */
   4 /* Copyright (C) 2009,2010,2013,2014 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_GLASS_INVERTER_H
  22 #define XAPIAN_INCLUDED_GLASS_INVERTER_H
  23
  24 #include "xapian/types.h"
  25
  26 #include <map>
  27 #include <string>
  28 #include <vector>
  29
  30 #include "omassert.h"
  31 #include "str.h"
  32 #include "xapian/error.h"
  33
  34 class GlassPostListTable;
  35 class GlassPositionListTable;
  36
  37 namespace Xapian {
  38 class TermIterator;
  39 }
  40
  41 /** Magic wdf value used for a deleted posting. */
  42 const Xapian::termcount DELETED_POSTING = Xapian::termcount(-1);
  43
  44 /** Class which "inverts the file". */
  45 class Inverter {
  46     friend class GlassPostListTable;
  47
  48     /// Class for storing the changes in frequencies for a term.
  49     class PostingChanges {
  50         friend class GlassPostListTable;
  51
  52         /// Change in term frequency,
  53         Xapian::termcount_diff tf_delta;
  54
  55         /// Change in collection frequency.
  56         Xapian::termcount_diff cf_delta;
  57
  58         /// Changes to this term's postlist.
  59         std::map<Xapian::docid, Xapian::termcount> pl_changes;
  60
  61       public:
  62         /// Constructor for an added posting.
  63         PostingChanges(Xapian::docid did, Xapian::termcount wdf)
  64             : tf_delta(1), cf_delta(Xapian::termcount_diff(wdf))
  65         {
  66             pl_changes.insert(std::make_pair(did, wdf));
  67         }
  68
  69         /// Constructor for a removed posting.
  70         PostingChanges(Xapian::docid did, Xapian::termcount wdf, bool)
  71             : tf_delta(-1), cf_delta(-Xapian::termcount_diff(wdf))
  72         {
  73             pl_changes.insert(std::make_pair(did, DELETED_POSTING));
  74         }
  75
  76         /// Constructor for an updated posting.
  77         PostingChanges(Xapian::docid did, Xapian::termcount old_wdf,
  78                        Xapian::termcount new_wdf)
  79             : tf_delta(0), cf_delta(Xapian::termcount_diff(new_wdf - old_wdf))
  80         {
  81             pl_changes.insert(std::make_pair(did, new_wdf));
  82         }
  83
  84         /// Add a posting.
  85         void add_posting(Xapian::docid did, Xapian::termcount wdf) {
  86             ++tf_delta;
  87             cf_delta += wdf;
  88             // Add did to term's postlist
  89             pl_changes[did] = wdf;
  90         }
  91
  92         /// Remove a posting.
  93         void remove_posting(Xapian::docid did, Xapian::termcount wdf) {
  94             --tf_delta;
  95             cf_delta -= wdf;
  96             // Remove did from term's postlist.
  97             pl_changes[did] = DELETED_POSTING;
  98         }
  99
 100         /// Update a posting.
 101         void update_posting(Xapian::docid did, Xapian::termcount old_wdf,
 102                             Xapian::termcount new_wdf) {
 103             cf_delta += new_wdf - old_wdf;
 104             pl_changes[did] = new_wdf;
 105         }
 106
 107         /// Get the term frequency delta.
 108         Xapian::termcount_diff get_tfdelta() const { return tf_delta; }
 109
 110         /// Get the collection frequency delta.
 111         Xapian::termcount_diff get_cfdelta() const { return cf_delta; }
 112     };
 113
 114     /// Buffered changes to postlists.
 115     std::map<std::string, PostingChanges> postlist_changes;
 116
 117     /// Buffered changes to positional data.
 118     std::map<std::string, std::map<Xapian::docid, std::string> > pos_changes;
 119
 120     void store_positions(const GlassPositionListTable & position_table,
 121                          Xapian::docid did,
 122                          const std::string & tname,
 123                          const std::vector<Xapian::termpos> & posvec,
 124                          bool modifying);
 125
 126     void set_positionlist(Xapian::docid did,
 127                           const std::string & term,
 128                           const std::string & s);
 129
 130   public:
 131     /// Buffered changes to document lengths.
 132     std::map<Xapian::docid, Xapian::termcount> doclen_changes;
 133
 134   public:
 135     void add_posting(Xapian::docid did, const std::string & term,
 136                      Xapian::doccount wdf) {
 137         std::map<std::string, PostingChanges>::iterator i;
 138         i = postlist_changes.find(term);
 139         if (i == postlist_changes.end()) {
 140             postlist_changes.insert(
 141                 std::make_pair(term, PostingChanges(did, wdf)));
 142         } else {
 143             i->second.add_posting(did, wdf);
 144         }
 145     }
 146
 147     void remove_posting(Xapian::docid did, const std::string & term,
 148                         Xapian::doccount wdf) {
 149         std::map<std::string, PostingChanges>::iterator i;
 150         i = postlist_changes.find(term);
 151         if (i == postlist_changes.end()) {
 152             postlist_changes.insert(
 153                 std::make_pair(term, PostingChanges(did, wdf, false)));
 154         } else {
 155             i->second.remove_posting(did, wdf);
 156         }
 157     }
 158
 159     void update_posting(Xapian::docid did, const std::string & term,
 160                         Xapian::termcount old_wdf,
 161                         Xapian::termcount new_wdf) {
 162         std::map<std::string, PostingChanges>::iterator i;
 163         i = postlist_changes.find(term);
 164         if (i == postlist_changes.end()) {
 165             postlist_changes.insert(
 166                 std::make_pair(term, PostingChanges(did, old_wdf, new_wdf)));
 167         } else {
 168             i->second.update_posting(did, old_wdf, new_wdf);
 169         }
 170     }
 171
 172     void set_positionlist(const GlassPositionListTable & position_table,
 173                           Xapian::docid did,
 174                           const std::string & tname,
 175                           const Xapian::TermIterator & term,
 176                           bool modifying = false);
 177
 178     void delete_positionlist(Xapian::docid did,
 179                              const std::string & term);
 180
 181     bool get_positionlist(Xapian::docid did,
 182                           const std::string & term,
 183                           std::string & s) const;
 184
 185     bool has_positions(const GlassPositionListTable & position_table) const;
 186
 187     void clear() {
 188         doclen_changes.clear();
 189         postlist_changes.clear();
 190         pos_changes.clear();
 191     }
 192
 193     void set_doclength(Xapian::docid did, Xapian::termcount doclen, bool add) {
 194         if (add) {
 195             Assert(doclen_changes.find(did) == doclen_changes.end() || doclen_changes[did] == DELETED_POSTING);
 196         }
 197         doclen_changes[did] = doclen;
 198     }
 199
 200     void delete_doclength(Xapian::docid did) {
 201         Assert(doclen_changes.find(did) == doclen_changes.end() || doclen_changes[did] != DELETED_POSTING);
 202         doclen_changes[did] = DELETED_POSTING;
 203     }
 204
 205     bool get_doclength(Xapian::docid did, Xapian::termcount & doclen) const {
 206         std::map<Xapian::docid, Xapian::termcount>::const_iterator i;
 207         i = doclen_changes.find(did);
 208         if (i == doclen_changes.end())
 209             return false;
 210         if (rare(i->second == DELETED_POSTING))
 211             throw Xapian::DocNotFoundError("Document not found: " + str(did));
 212         doclen = i->second;
 213         return true;
 214     }
 215
 216     /// Flush document length changes.
 217     void flush_doclengths(GlassPostListTable & table);
 218
 219     /// Flush postlist changes for @a term.
 220     void flush_post_list(GlassPostListTable & table, const std::string & term);
 221
 222     /// Flush postlist changes for all terms.
 223     void flush_all_post_lists(GlassPostListTable & table);
 224
 225     /// Flush postlist changes for all terms which start with @a pfx.
 226     void flush_post_lists(GlassPostListTable & table, const std::string & pfx);
 227
 228     /// Flush all postlist table changes.
 229     void flush(GlassPostListTable & table);
 230
 231     /// Flush position changes.
 232     void flush_pos_lists(GlassPositionListTable & table);
 233
 234     bool get_deltas(const std::string & term,
 235                     Xapian::termcount_diff & tf_delta,
 236                     Xapian::termcount_diff & cf_delta) const {
 237         std::map<std::string, PostingChanges>::const_iterator i;
 238         i = postlist_changes.find(term);
 239         if (i == postlist_changes.end()) {
 240             return false;
 241         }
 242         tf_delta = i->second.get_tfdelta();
 243         cf_delta = i->second.get_cfdelta();
 244         return true;
 245     }
 246 };
 247
 248 #endif // XAPIAN_INCLUDED_GLASS_INVERTER_H