include/xapian/postingsource.h

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/* Copyright (C) 2007,2008,2009,2010,2011,2012 Olly Betts
 * Copyright (C) 2008,2009 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 XAPIAN_INCLUDED_POSTINGSOURCE_H
#define XAPIAN_INCLUDED_POSTINGSOURCE_H

#include <xapian/database.h>
#include <xapian/types.h>
#include <xapian/visibility.h>

#include <string>
#include <map>

namespace Xapian {

class XAPIAN_VISIBILITY_DEFAULT PostingSource {
    void operator=(const PostingSource &);

    PostingSource(const PostingSource &);

    double max_weight_;

    void * matcher_;

  protected:
    PostingSource() : max_weight_(0), matcher_(NULL) { }

    void set_maxweight(Xapian::weight max_weight);

  public:
    void register_matcher_(void * matcher) { matcher_ = matcher; }

    // Destructor.
    virtual ~PostingSource();

    virtual Xapian::doccount get_termfreq_min() const = 0;

    virtual Xapian::doccount get_termfreq_est() const = 0;

    virtual Xapian::doccount get_termfreq_max() const = 0;

    Xapian::weight get_maxweight() const { return max_weight_; }

    virtual Xapian::weight get_weight() const;

    virtual Xapian::docid get_docid() const = 0;

    virtual void next(Xapian::weight min_wt) = 0;

    virtual void skip_to(Xapian::docid did, Xapian::weight min_wt);

    virtual bool check(Xapian::docid did, Xapian::weight min_wt);

    virtual bool at_end() const = 0;

    virtual PostingSource * clone() const;

    virtual std::string name() const;

    virtual std::string serialise() const;

    virtual PostingSource * unserialise(const std::string &s) const;

    virtual void init(const Database & db) = 0;

    virtual std::string get_description() const;
};


class XAPIAN_VISIBILITY_DEFAULT ValuePostingSource : public PostingSource {
  protected:
    Xapian::Database db;

    Xapian::valueno slot;

    Xapian::ValueIterator value_it;

    bool started;

    Xapian::doccount termfreq_min;

    Xapian::doccount termfreq_est;

    Xapian::doccount termfreq_max;

  public:
    ValuePostingSource(Xapian::valueno slot_);

    Xapian::doccount get_termfreq_min() const;
    Xapian::doccount get_termfreq_est() const;
    Xapian::doccount get_termfreq_max() const;

    void next(Xapian::weight min_wt);
    void skip_to(Xapian::docid min_docid, Xapian::weight min_wt);
    bool check(Xapian::docid min_docid, Xapian::weight min_wt);

    bool at_end() const;

    Xapian::docid get_docid() const;

    void init(const Database & db_);
};


class XAPIAN_VISIBILITY_DEFAULT ValueWeightPostingSource
        : public ValuePostingSource {
  public:
    ValueWeightPostingSource(Xapian::valueno slot_);

    Xapian::weight get_weight() const;
    ValueWeightPostingSource * clone() const;
    std::string name() const;
    std::string serialise() const;
    ValueWeightPostingSource * unserialise(const std::string &s) const;
    void init(const Database & db_);

    std::string get_description() const;
};


class XAPIAN_VISIBILITY_DEFAULT DecreasingValueWeightPostingSource
        : public Xapian::ValueWeightPostingSource {
  protected:
    Xapian::docid range_start;
    Xapian::docid range_end;
    double curr_weight;

    bool items_at_end;

    void skip_if_in_range(Xapian::weight min_wt);

  public:
    DecreasingValueWeightPostingSource(Xapian::valueno slot_,
                                       Xapian::docid range_start_ = 0,
                                       Xapian::docid range_end_ = 0);

    Xapian::weight get_weight() const;
    DecreasingValueWeightPostingSource * clone() const;
    std::string name() const;
    std::string serialise() const;
    DecreasingValueWeightPostingSource * unserialise(const std::string &s) const;
    void init(const Xapian::Database & db_);

    void next(Xapian::weight min_wt);
    void skip_to(Xapian::docid min_docid, Xapian::weight min_wt);
    bool check(Xapian::docid min_docid, Xapian::weight min_wt);

    std::string get_description() const;
};


class XAPIAN_VISIBILITY_DEFAULT ValueMapPostingSource
        : public ValuePostingSource {
    double default_weight;

    double max_weight_in_map;

    std::map<std::string, double> weight_map;

  public:
    ValueMapPostingSource(Xapian::valueno slot_);

    void add_mapping(const std::string &key, double wt);

    void clear_mappings();

    void set_default_weight(double wt);

    Xapian::weight get_weight() const;
    ValueMapPostingSource * clone() const;
    std::string name() const;
    std::string serialise() const;
    ValueMapPostingSource * unserialise(const std::string &s) const;
    void init(const Database & db_);

    std::string get_description() const;
};


class XAPIAN_VISIBILITY_DEFAULT FixedWeightPostingSource : public PostingSource {
    Xapian::Database db;

    Xapian::doccount termfreq;

    Xapian::PostingIterator it;

    bool started;

    Xapian::docid check_docid;

  public:
    FixedWeightPostingSource(Xapian::weight wt);

    Xapian::doccount get_termfreq_min() const;
    Xapian::doccount get_termfreq_est() const;
    Xapian::doccount get_termfreq_max() const;

    Xapian::weight get_weight() const;

    void next(Xapian::weight min_wt);
    void skip_to(Xapian::docid min_docid, Xapian::weight min_wt);
    bool check(Xapian::docid min_docid, Xapian::weight min_wt);

    bool at_end() const;

    Xapian::docid get_docid() const;

    FixedWeightPostingSource * clone() const;
    std::string name() const;
    std::string serialise() const;
    FixedWeightPostingSource * unserialise(const std::string &s) const;
    void init(const Database & db_);

    std::string get_description() const;
};


}

#endif // XAPIAN_INCLUDED_POSTINGSOURCE_H

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