xapian-core/matcher/valuestreamdocument.h

   1 /** @file
   2  * @brief A document which gets its values from a ValueStreamManager.
   3  */
   4 /* Copyright (C) 2009,2011,2014,2017 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_VALUESTREAMDOCUMENT_H
  22 #define XAPIAN_INCLUDED_VALUESTREAMDOCUMENT_H
  23
  24 #include "backends/documentinternal.h"
  25 #include "backends/multi.h"
  26 #include "backends/multi/multi_database.h"
  27 #include "backends/valuelist.h"
  28 #include "omassert.h"
  29 #include "xapian/database.h"
  30 #include "xapian/types.h"
  31
  32 #include <map>
  33
  34 /// A document which gets its values from a ValueStreamManager.
  35 class ValueStreamDocument : public Xapian::Document::Internal {
  36     /// Don't allow assignment.
  37     void operator=(const ValueStreamDocument &);
  38
  39     /// Don't allow copying.
  40     ValueStreamDocument(const ValueStreamDocument &);
  41
  42     mutable std::map<Xapian::valueno, ValueList *> valuelists;
  43
  44     Xapian::Database db;
  45
  46     Xapian::doccount current = 0;
  47
  48     Xapian::doccount n_shards;
  49
  50     mutable Xapian::Document::Internal * doc = NULL;
  51
  52     /** Private constructor.
  53      *
  54      *  This is an implementation detail - the public constructor forwards to
  55      *  this constructor so we can use n_shards_ to init our parent class.
  56      */
  57     ValueStreamDocument(const Xapian::Database& db_, Xapian::doccount n_shards_)
  58         : Internal(n_shards_ == 1 ?
  59                    db_.internal.get() :
  60                    static_cast<MultiDatabase*>(db_.internal.get())->shards[0],
  61                    0),
  62           db(db_),
  63           n_shards(n_shards_) {}
  64
  65   public:
  66     explicit ValueStreamDocument(const Xapian::Database& db_)
  67         : ValueStreamDocument(db_, db_.internal->size()) {}
  68
  69     void new_shard(Xapian::doccount n);
  70
  71     ~ValueStreamDocument();
  72
  73     void set_shard_document(Xapian::docid shard_did) {
  74         if (did != shard_did) {
  75             did = shard_did;
  76             delete doc;
  77             doc = NULL;
  78         }
  79     }
  80
  81     void set_document(Xapian::docid did_) {
  82         AssertEq(current, shard_number(did_, n_shards));
  83         set_shard_document(shard_docid(did_, n_shards));
  84     }
  85
  86     // Optimise away the virtual call when the matcher wants to know a value.
  87     std::string get_value(Xapian::valueno slot) const {
  88         return ValueStreamDocument::fetch_value(slot);
  89     }
  90
  91   protected:
  92     /** Implementation of virtual methods @{ */
  93     std::string fetch_value(Xapian::valueno slot) const;
  94     void fetch_all_values(std::map<Xapian::valueno, std::string> & values_) const;
  95     std::string fetch_data() const;
  96     /** @} */
  97 };
  98
  99 #endif // XAPIAN_INCLUDED_VALUESTREAMDOCUMENT_H