matcher/queryoptimiser.h

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/* Copyright (C) 2007,2008 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#ifndef XAPIAN_INCLUDED_QUERYOPTIMISER_H
#define XAPIAN_INCLUDED_QUERYOPTIMISER_H

#include <xapian/query.h>

#include "database.h"
#include "localmatch.h"
#include "omenquireinternal.h"
#include "postlist.h"

#include <list>
#include <map>
#include <vector>

class MultiMatch;
struct PosFilter;

class QueryOptimiser {
    const Xapian::Database::Internal & db;

    Xapian::doccount db_size;

    LocalSubMatch & localsubmatch;

    MultiMatch * matcher;

    PostList * do_subquery(const Xapian::Query::Internal * query,
                           double factor);

    PostList * do_leaf(const Xapian::Query::Internal * query, double factor) {
        if (query->tname.empty()) factor = 0.0;
        return localsubmatch.postlist_from_op_leaf_query(query, factor);
    }

    PostList * do_and_like(const Xapian::Query::Internal *query, double factor);

    void do_and_like(const Xapian::Query::Internal *query, double factor,
                     std::vector<PostList *> & and_plists,
                     std::list<PosFilter> & pos_filters);

    PostList * do_or_like(const Xapian::Query::Internal *query, double factor);

  public:
    QueryOptimiser(const Xapian::Database::Internal & db_,
                   LocalSubMatch & localsubmatch_,
                   MultiMatch * matcher_)
        : db(db_), db_size(db.get_doccount()), localsubmatch(localsubmatch_),
          matcher(matcher_) { }

    PostList * optimise_query(Xapian::Query::Internal * query) {
        return do_subquery(query, 1.0);
    }
};

#endif // XAPIAN_INCLUDED_QUERYOPTIMISER_H

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