geospatial.h

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/* Copyright 2008,2009 Lemur Consulting Ltd
 * Copyright 2010,2011 Richard Boulton
 * Copyright 2012,2013,2014,2015,2016,2024 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_GEOSPATIAL_H
#define XAPIAN_INCLUDED_GEOSPATIAL_H
 
#if !defined XAPIAN_IN_XAPIAN_H && !defined XAPIAN_LIB_BUILD
# error Never use <xapian/geospatial.h> directly; include <xapian.h> instead.
#endif
 
#include <iterator>
#include <vector>
#include <string>
#include <string_view>
 
#include <xapian/attributes.h>
#include <xapian/derefwrapper.h>
#include <xapian/keymaker.h>
#include <xapian/postingsource.h>
#include <xapian/queryparser.h> // For sortable_serialise
#include <xapian/visibility.h>
 
namespace Xapian {
 
class Registry;
 
double
miles_to_metres(double miles) noexcept XAPIAN_CONST_FUNCTION;
 
inline double
miles_to_metres(double miles) noexcept
{
    return 1609.344 * miles;
}
 
double
metres_to_miles(double metres) noexcept XAPIAN_CONST_FUNCTION;
 
inline double
metres_to_miles(double metres) noexcept
{
    return metres * (1.0 / 1609.344);
}
 
struct XAPIAN_VISIBILITY_DEFAULT LatLongCoord {
    double latitude;
 
    double longitude;
 
    LatLongCoord() noexcept {}
 
    LatLongCoord(double latitude_, double longitude_);
 
    void unserialise(std::string_view serialised);
 
    void unserialise(const char ** ptr, const char * end);
 
    std::string serialise() const;
 
    bool operator<(const LatLongCoord& other) const noexcept {
        if (latitude < other.latitude) return true;
        if (latitude > other.latitude) return false;
        return (longitude < other.longitude);
    }
 
    std::string get_description() const;
};
 
class XAPIAN_VISIBILITY_DEFAULT LatLongCoordsIterator {
    friend class LatLongCoords;
 
    std::vector<LatLongCoord>::const_iterator iter;
 
    LatLongCoordsIterator(std::vector<LatLongCoord>::const_iterator iter_)
            : iter(iter_) {}
 
  public:
    LatLongCoordsIterator() {}
 
    const LatLongCoord & operator*() const {
        return *iter;
    }
 
    LatLongCoordsIterator & operator++() {
        ++iter;
        return *this;
    }
 
    DerefWrapper_<LatLongCoord> operator++(int) {
        const LatLongCoord & tmp = **this;
        ++iter;
        return DerefWrapper_<LatLongCoord>(tmp);
    }
 
    bool operator==(const LatLongCoordsIterator &other) const
    {
        return iter == other.iter;
    }
 
    // @{
    typedef std::input_iterator_tag iterator_category;
    typedef LatLongCoord value_type;
    typedef size_t difference_type;
    typedef LatLongCoord * pointer;
    typedef LatLongCoord & reference;
    // @}
};
 
class XAPIAN_VISIBILITY_DEFAULT LatLongCoords {
    std::vector<LatLongCoord> coords;
 
  public:
    LatLongCoordsIterator begin() const {
        return LatLongCoordsIterator(coords.begin());
    }
 
    LatLongCoordsIterator end() const {
        return LatLongCoordsIterator(coords.end());
    }
 
    size_t size() const
    {
        return coords.size();
    }
 
    bool empty() const
    {
        return coords.empty();
    }
 
    void append(const LatLongCoord & coord)
    {
        coords.push_back(coord);
    }
 
    LatLongCoords() : coords() {}
 
    LatLongCoords(const LatLongCoord & coord) : coords()
    {
        coords.push_back(coord);
    }
 
    void unserialise(std::string_view serialised);
 
    std::string serialise() const;
 
    std::string get_description() const;
};
 
inline bool
operator!=(const LatLongCoordsIterator &a, const LatLongCoordsIterator &b)
{
    return !(a == b);
}
 
class XAPIAN_VISIBILITY_DEFAULT LatLongMetric {
  public:
    virtual ~LatLongMetric();
 
    virtual double pointwise_distance(const LatLongCoord & a,
                                      const LatLongCoord & b) const = 0;
 
    double operator()(const LatLongCoords & a, const LatLongCoords & b) const;
 
    double operator()(const LatLongCoords& a, std::string_view b) const
    {
        return (*this)(a, b.data(), b.size());
    }
 
    double operator()(const LatLongCoords & a,
                      const char * b_ptr, size_t b_len) const;
 
    virtual LatLongMetric * clone() const = 0;
 
    virtual std::string name() const = 0;
 
    virtual std::string serialise() const = 0;
 
    virtual LatLongMetric * unserialise(const std::string & serialised) const = 0;
};
 
class XAPIAN_VISIBILITY_DEFAULT GreatCircleMetric : public LatLongMetric {
    double radius;
 
  public:
    GreatCircleMetric();
 
    explicit GreatCircleMetric(double radius_);
 
    double pointwise_distance(const LatLongCoord & a,
                              const LatLongCoord &b) const;
 
    LatLongMetric * clone() const;
    std::string name() const;
    std::string serialise() const;
    LatLongMetric * unserialise(const std::string & serialised) const;
};
 
class XAPIAN_VISIBILITY_DEFAULT LatLongDistancePostingSource : public ValuePostingSource
{
    double dist;
 
    LatLongCoords centre;
 
    const LatLongMetric * metric;
 
    double max_range;
 
    double k1;
 
    double k2;
 
    void calc_distance();
 
    LatLongDistancePostingSource(Xapian::valueno slot_,
                                 const LatLongCoords & centre_,
                                 const LatLongMetric * metric_,
                                 double max_range_,
                                 double k1_,
                                 double k2_);
 
  public:
    LatLongDistancePostingSource(Xapian::valueno slot_,
                                 const LatLongCoords & centre_,
                                 const LatLongMetric & metric_,
                                 double max_range_ = 0.0,
                                 double k1_ = 1000.0,
                                 double k2_ = 1.0);
 
    LatLongDistancePostingSource(Xapian::valueno slot_,
                                 const LatLongCoords & centre_,
                                 double max_range_ = 0.0,
                                 double k1_ = 1000.0,
                                 double k2_ = 1.0);
    ~LatLongDistancePostingSource();
 
    void next(double min_wt);
    void skip_to(Xapian::docid min_docid, double min_wt);
    bool check(Xapian::docid min_docid, double min_wt);
 
    double get_weight() const;
    LatLongDistancePostingSource * clone() const;
    std::string name() const;
    std::string serialise() const;
    LatLongDistancePostingSource *
            unserialise_with_registry(const std::string &serialised,
                                      const Registry & registry) const;
    void reset(const Database& db_, Xapian::doccount shard_index);
 
    std::string get_description() const;
};
 
class XAPIAN_VISIBILITY_DEFAULT LatLongDistanceKeyMaker : public KeyMaker {
 
    Xapian::valueno slot;
 
    LatLongCoords centre;
 
    const LatLongMetric * metric;
 
    std::string defkey;
 
  public:
    LatLongDistanceKeyMaker(Xapian::valueno slot_,
                            const LatLongCoords & centre_,
                            const LatLongMetric & metric_,
                            double defdistance)
            : slot(slot_),
              centre(centre_),
              metric(metric_.clone()),
              defkey(sortable_serialise(defdistance))
    {}
 
    LatLongDistanceKeyMaker(Xapian::valueno slot_,
                            const LatLongCoords & centre_,
                            const LatLongMetric & metric_)
            : slot(slot_),
              centre(centre_),
              metric(metric_.clone()),
              defkey(9, '\xff')
    {}
 
    LatLongDistanceKeyMaker(Xapian::valueno slot_,
                            const LatLongCoords & centre_)
            : slot(slot_),
              centre(centre_),
              metric(new Xapian::GreatCircleMetric()),
              defkey(9, '\xff')
    {}
 
    LatLongDistanceKeyMaker(Xapian::valueno slot_,
                            const LatLongCoord & centre_,
                            const LatLongMetric & metric_,
                            double defdistance)
            : slot(slot_),
              centre(),
              metric(metric_.clone()),
              defkey(sortable_serialise(defdistance))
    {
        centre.append(centre_);
    }
 
    LatLongDistanceKeyMaker(Xapian::valueno slot_,
                            const LatLongCoord & centre_,
                            const LatLongMetric & metric_)
            : slot(slot_),
              centre(),
              metric(metric_.clone()),
              defkey(9, '\xff')
    {
        centre.append(centre_);
    }
 
    LatLongDistanceKeyMaker(Xapian::valueno slot_,
                            const LatLongCoord & centre_)
            : slot(slot_),
              centre(),
              metric(new Xapian::GreatCircleMetric()),
              defkey(9, '\xff')
    {
        centre.append(centre_);
    }
 
    ~LatLongDistanceKeyMaker();
 
    std::string operator()(const Xapian::Document & doc) const;
};
 
}
 
#endif /* XAPIAN_INCLUDED_GEOSPATIAL_H */