postingsource.h

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/* Copyright (C) 2007-2026 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, see
 * <https://www.gnu.org/licenses/>.
 */
 
#ifndef XAPIAN_INCLUDED_POSTINGSOURCE_H
#define XAPIAN_INCLUDED_POSTINGSOURCE_H
 
#if !defined XAPIAN_IN_XAPIAN_H && !defined XAPIAN_LIB_BUILD
# error Never use <xapian/postingsource.h> directly; include <xapian.h> instead.
#endif
 
#include <xapian/attributes.h>
#include <xapian/database.h>
#include <xapian/intrusive_ptr.h>
#include <xapian/postingiterator.h>
#include <xapian/types.h>
#include <xapian/valueiterator.h>
#include <xapian/visibility.h>
 
#include <string>
#include <map>
 
namespace Xapian {
 
class Registry;
 
class XAPIAN_VISIBILITY_DEFAULT PostingSource
    : public Xapian::Internal::opt_intrusive_base {
    void operator=(const PostingSource &) = delete;
 
    PostingSource(const PostingSource &) = delete;
 
    double max_weight_ = 0.0;
 
    bool* max_weight_cached_flag_ptr = nullptr;
 
  public:
    PostingSource() noexcept { }
 
    XAPIAN_VISIBILITY_INTERNAL
    void set_max_weight_cached_flag_ptr_(bool* flag_ptr) {
        max_weight_cached_flag_ptr = flag_ptr;
    }
 
    // 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;
 
    void set_maxweight(double max_weight) {
        max_weight_ = max_weight;
        if (max_weight_cached_flag_ptr) {
            *max_weight_cached_flag_ptr = false;
        }
    }
 
    double get_maxweight() const noexcept { return max_weight_; }
 
    virtual double get_weight() const;
 
    virtual Xapian::docid get_docid() const = 0;
 
    virtual void next(double min_wt) = 0;
 
    virtual void skip_to(Xapian::docid did, double min_wt);
 
    virtual bool check(Xapian::docid did, double 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 &serialised) const;
 
    virtual PostingSource * unserialise_with_registry(const std::string &serialised,
                                      const Registry & registry) const;
 
    virtual void reset(const Database& db, Xapian::doccount shard_index);
 
    virtual void init(const Database& db);
 
    virtual std::string get_description() const;
 
    PostingSource * release() {
        opt_intrusive_base::release();
        return this;
    }
 
    const PostingSource * release() const {
        opt_intrusive_base::release();
        return this;
    }
};
 
 
class XAPIAN_VISIBILITY_DEFAULT ValuePostingSource : public PostingSource {
    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:
    explicit ValuePostingSource(Xapian::valueno slot_) noexcept
        : slot(slot_) {}
 
    Xapian::doccount get_termfreq_min() const;
    Xapian::doccount get_termfreq_est() const;
    Xapian::doccount get_termfreq_max() const;
 
    void next(double min_wt);
    void skip_to(Xapian::docid min_docid, double min_wt);
    bool check(Xapian::docid min_docid, double min_wt);
 
    bool at_end() const;
 
    Xapian::docid get_docid() const;
 
    void reset(const Database& db_, Xapian::doccount shard_index);
 
    Xapian::Database get_database() const { return db; }
 
    Xapian::valueno get_slot() const { return slot; }
 
    std::string get_value() const { return *value_it; }
 
    void done() {
        value_it = db.valuestream_end(slot);
        started = true;
    }
 
    bool get_started() const { return started; }
 
    void set_termfreq_min(Xapian::doccount termfreq_min_) {
        termfreq_min = termfreq_min_;
    }
 
    void set_termfreq_est(Xapian::doccount termfreq_est_) {
        termfreq_est = termfreq_est_;
    }
 
    void set_termfreq_max(Xapian::doccount termfreq_max_) {
        termfreq_max = termfreq_max_;
    }
 
    std::string get_description() const;
};
 
 
class XAPIAN_VISIBILITY_DEFAULT ValueWeightPostingSource
        : public ValuePostingSource {
  public:
    explicit ValueWeightPostingSource(Xapian::valueno slot_);
 
    double get_weight() const;
    ValueWeightPostingSource * clone() const;
    std::string name() const;
    std::string serialise() const;
    ValueWeightPostingSource * unserialise(const std::string &serialised) const;
    void reset(const Database& db_, Xapian::doccount shard_index);
 
    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(double min_wt);
 
  public:
    DecreasingValueWeightPostingSource(Xapian::valueno slot_,
                                       Xapian::docid range_start_ = 0,
                                       Xapian::docid range_end_ = 0);
 
    double get_weight() const override;
    DecreasingValueWeightPostingSource* clone() const override;
    std::string name() const override;
    std::string serialise() const override;
    DecreasingValueWeightPostingSource*
        unserialise(const std::string& serialised) const override;
    void reset(const Database& db_, Xapian::doccount shard_index) override;
 
    void next(double min_wt) override;
    void skip_to(Xapian::docid min_docid, double min_wt) override;
    bool check(Xapian::docid min_docid, double min_wt) override;
 
    std::string get_description() const override;
};
 
 
class XAPIAN_VISIBILITY_DEFAULT ValueMapPostingSource
        : public ValuePostingSource {
    double default_weight;
 
    double max_weight_in_map;
 
    std::map<std::string, double> weight_map;
 
  public:
    explicit ValueMapPostingSource(Xapian::valueno slot_);
 
    void add_mapping(const std::string &key, double wt);
 
    void clear_mappings();
 
    void set_default_weight(double wt);
 
    double get_weight() const override;
    ValueMapPostingSource* clone() const override;
    std::string name() const override;
    std::string serialise() const override;
    ValueMapPostingSource*
        unserialise(const std::string& serialised) const override;
    void reset(const Database& db_, Xapian::doccount shard_index) override;
 
    std::string get_description() const override;
};
 
 
class XAPIAN_VISIBILITY_DEFAULT FixedWeightPostingSource : public PostingSource {
    Xapian::Database db;
 
    Xapian::doccount termfreq;
 
    Xapian::PostingIterator it;
 
    bool started;
 
    Xapian::docid check_docid;
 
  public:
    explicit FixedWeightPostingSource(double wt);
 
    Xapian::doccount get_termfreq_min() const override;
    Xapian::doccount get_termfreq_est() const override;
    Xapian::doccount get_termfreq_max() const override;
 
    double get_weight() const override;
 
    void next(double min_wt) override;
    void skip_to(Xapian::docid min_docid, double min_wt) override;
    bool check(Xapian::docid min_docid, double min_wt) override;
 
    bool at_end() const override;
 
    Xapian::docid get_docid() const override;
 
    FixedWeightPostingSource* clone() const override;
    std::string name() const override;
    std::string serialise() const override;
    FixedWeightPostingSource*
        unserialise(const std::string& serialised) const override;
    void reset(const Database& db_, Xapian::doccount shard_index) override;
 
    std::string get_description() const override;
};
 
}
 
#endif // XAPIAN_INCLUDED_POSTINGSOURCE_H