common/stats.h

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/* stats.h: Handling of statistics needed for the search.
 *
 * Copyright 1999,2000,2001 BrightStation PLC
 * Copyright 2002,2003,2005,2007 Olly Betts
 * Copyright 2007 Lemur Consulting Ltd
 *
 * 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 OM_HGUARD_STATS_H
#define OM_HGUARD_STATS_H

#include "xapian/types.h"
#include "omassert.h"
#include <string>
#include <map>

#include "autoptr.h" // FIXME:1.1: remove this
#include "weightinternal.h" // FIXME:1.1: remove this
#include <list> // FIXME:1.1: remove this

using namespace std;

class Stats {
    public:
        Xapian::doccount collection_size;

        Xapian::doccount rset_size;

        Xapian::doclength average_length;

        std::map<string, Xapian::doccount> termfreq;

        std::map<string, Xapian::doccount> reltermfreq;


        Stats() : collection_size(0),
                  rset_size(0),
                  average_length(1.0)
        {}

        Stats & operator +=(const Stats & inc);

        Xapian::doccount get_termfreq(const string & tname) const;

        void set_termfreq(const string & tname, Xapian::doccount tfreq);

        Xapian::doccount get_reltermfreq(const string & tname) const;

        void set_reltermfreq(const string & tname, Xapian::doccount rtfreq);

        string get_description() const;


        mutable list<Xapian::Weight::Internal *> weight_internals;

        ~Stats() {
            list<Xapian::Weight::Internal *>::const_iterator i;
            for (i = weight_internals.begin(); i != weight_internals.end(); ++i)
            {
                delete *i;
            }
        }

        Xapian::Weight::Internal * create_weight_internal() const
        {
            AutoPtr<Xapian::Weight::Internal> wti(new Xapian::Weight::Internal(*this));
            weight_internals.push_back(wti.get());
            return wti.release();
        }

        Xapian::Weight::Internal * create_weight_internal(const string & tname) const
        {
            AutoPtr<Xapian::Weight::Internal> wti(new Xapian::Weight::Internal(*this, tname));
            weight_internals.push_back(wti.get());
            return wti.release();
        }
};

// Inline method definitions for Stats //

inline Stats &
Stats::operator +=(const Stats & inc)
{
    // Set the new collection size and average length.
    Xapian::doccount new_collection_size = collection_size + inc.collection_size;
    if (new_collection_size != 0) {
        // Cope with adding in a collection of zero size at the beginning:
        // perhaps we have multiple databases, but some are not yet populated
        average_length = (average_length * collection_size +
                          inc.average_length * inc.collection_size) /
                         new_collection_size;
    }
    collection_size = new_collection_size;

    // Add the rset size.
    rset_size += inc.rset_size;

    // Add termfreqs and reltermfreqs
    std::map<string, Xapian::doccount>::const_iterator i;
    for (i = inc.termfreq.begin(); i != inc.termfreq.end(); ++i) {
        termfreq[i->first] += i->second;
    }
    for (i = inc.reltermfreq.begin(); i != inc.reltermfreq.end(); ++i) {
        reltermfreq[i->first] += i->second;
    }
    return *this;
}

inline Xapian::doccount
Stats::get_termfreq(const string & tname) const
{
    // We pass an empty string for tname when calculating the extra weight.
    if (tname.empty()) return 0;

    std::map<string, Xapian::doccount>::const_iterator tfreq;
    tfreq = termfreq.find(tname);
    Assert(tfreq != termfreq.end());
    return tfreq->second;
}

inline void
Stats::set_termfreq(const string & tname, Xapian::doccount tfreq)
{
    // Can be called a second time, if a term occurs multiple times in the
    // query; if this happens, the termfreq should be the same each time.
    Assert(termfreq.find(tname) == termfreq.end() ||
           termfreq.find(tname)->second == tfreq);
    termfreq[tname] = tfreq;
}

inline Xapian::doccount
Stats::get_reltermfreq(const string & tname) const
{
    // We pass an empty string for tname when calculating the extra weight.
    if (tname.empty()) return 0;

    std::map<string, Xapian::doccount>::const_iterator rtfreq;
    rtfreq = reltermfreq.find(tname);
    Assert(rtfreq != reltermfreq.end());
    return rtfreq->second;
}

inline void
Stats::set_reltermfreq(const string & tname, Xapian::doccount rtfreq)
{
    // Can be called a second time, if a term occurs multiple times in the
    // query; if this happens, the termfreq should be the same each time.
    Assert(reltermfreq.find(tname) == reltermfreq.end() ||
           reltermfreq.find(tname)->second == rtfreq);
    reltermfreq[tname] = rtfreq;
}

#endif /* OM_HGUARD_STATS_H */

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