multi_valuelist.h

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/* Copyright (C) 2007,2008,2009,2017 Olly Betts
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see
 * <https://www.gnu.org/licenses/>.
 */
 
#ifndef XAPIAN_INCLUDED_MULTI_VALUELIST_H
#define XAPIAN_INCLUDED_MULTI_VALUELIST_H
 
#include "backends/valuelist.h"
 
#include "backends/databaseinternal.h"
#include "backends/multi.h"
 
#include <string>
 
struct SubValueList {
    ValueList * valuelist;
    unsigned shard;
 
    SubValueList(ValueList * vl, unsigned shard_)
        : valuelist(vl), shard(shard_) { }
 
    ~SubValueList() {
        delete valuelist;
    }
 
    void skip_to(Xapian::docid did, Xapian::doccount n_shards) {
        // Calculate the docid in this shard which is the same or later than
        // did (which may be in a different shard).
        Xapian::docid shard_did = shard_docid(did, n_shards);
        if (shard_number(did, n_shards) > shard)
            ++shard_did;
        valuelist->skip_to(shard_did);
    }
 
    Xapian::docid get_docid() const {
        return valuelist->get_docid();
    }
 
    Xapian::docid get_merged_docid(unsigned n_shards) const {
        return unshard(valuelist->get_docid(), shard, n_shards);
    }
 
    std::string get_value() const { return valuelist->get_value(); }
 
    void next() {
        valuelist->next();
    }
 
    bool at_end() const { return valuelist->at_end(); }
};
 
class MultiValueList : public ValueList {
    void operator=(const MultiValueList &);
 
    MultiValueList(const MultiValueList &);
 
    Xapian::docid current_docid = 0;
 
    Xapian::doccount count;
 
    SubValueList** valuelists;
 
    Xapian::valueno slot;
 
    Xapian::doccount n_shards;
 
  public:
    MultiValueList(Xapian::doccount n_shards_,
                   SubValueList** valuelists_,
                   Xapian::valueno slot_)
        : count(n_shards_),
          valuelists(valuelists_),
          slot(slot_),
          n_shards(n_shards_)
    {
    }
 
    ~MultiValueList();
 
    Xapian::docid get_docid() const;
 
    std::string get_value() const;
 
    Xapian::valueno get_valueno() const;
 
    bool at_end() const;
 
    void next();
 
    void skip_to(Xapian::docid);
 
    bool check(Xapian::docid did);
 
    std::string get_description() const;
};
 
#endif // XAPIAN_INCLUDED_MULTIVALUELIST_H