functor.h

Go to the documentation of this file.

#ifndef SQL_GIS_FUNCTOR_H_INCLUDED
#define SQL_GIS_FUNCTOR_H_INCLUDED
// Copyright (c) 2017, 2021, Oracle and/or its affiliates.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0,
// as published by the Free Software Foundation.
//
// This program is also distributed with certain software (including
// but not limited to OpenSSL) that is licensed under separate terms,
// as designated in a particular file or component or in included license
// documentation.  The authors of MySQL hereby grant you an additional
// permission to link the program and your derivative works with the
// separately licensed software that they have included with MySQL.
//
// 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, version 2.0, 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.
 
/// @file
///
/// This file contains the superclasses for GIS functors.
///
/// Each GIS function is split in two: a functor class (for internal use) and a
/// function (for external use) that uses the functor. The functor provides the
/// internal interface to GIS functions, and it may throw exceptions. Some
/// functions may need a combination of different functors to implement the
/// desired functionality.
///
/// The function, not the functor, is the interface to the rest of MySQL.
///
/// @see distance_functor.h
 
#include <assert.h>
#include <exception>  // std::exception
#include <sstream>    // std::stringstream
#include <string>     // std::string
 
// assert
#include "sql/gis/geometries.h"  // gis::{Geometry{,_type}, Coordinate_system}
#include "sql/gis/geometries_cs.h"  // gis::{Cartesian_*, Geographic_*}
#include "template_utils.h"         // down_cast
 
namespace gis {
 
/// Longitude out of range exception
///
/// Thrown by GIS functors when longtitude is out of range when reinterpreting
/// geometry coordinates.
struct longitude_out_of_range_exception : public std::exception {
  double value;
  double range_min;
  double range_max;
 
  longitude_out_of_range_exception(double value, double range_min,
                                   double range_max)
      : value{value}, range_min{range_min}, range_max{range_max} {}
};
 
/// Latitude out of range exception
///
/// Thrown by GIS functors when latitude is out of range when reinterpreting
/// geometry coordinates.
struct latitude_out_of_range_exception : public std::exception {
  double value;
  double range_min;
  double range_max;
 
  latitude_out_of_range_exception(double value, double range_min,
                                  double range_max)
      : value{value}, range_min{range_min}, range_max{range_max} {}
};
 
/// Function/parameter combination not implemented exception.
///
/// Geometry is tagged as geographic or Cartesian/projected. In the latter case,
/// whether it is Cartesian or projected is determined by the accompanying SRS.
///
/// To obtain an instance of this exception, use
/// not_implemented_exception::for_projected if geometry is projected, and
/// not_implemented_exception::for_non_projected otherwise.
class not_implemented_exception : public std::exception {
 public:
  enum Srs_type : char { kCartesian, kGeographic, kProjected };
 
 private:
  Srs_type m_srs_type;
 
  std::string m_typenames;
 
  not_implemented_exception(Srs_type srs_type, const Geometry &g) {
    m_srs_type = srs_type;
    m_typenames = std::string(type_to_name(g.type()));
  }
 
  not_implemented_exception(Srs_type srs_type, const Geometry &g1,
                            const Geometry &g2) {
    assert(g1.coordinate_system() == g2.coordinate_system());
    m_srs_type = srs_type;
    std::stringstream ss;
    ss << type_to_name(g1.type()) << ", " << type_to_name(g2.type());
    m_typenames = ss.str();
  }
 
 public:
  Srs_type srs_type() const { return m_srs_type; }
  const char *typenames() const { return m_typenames.c_str(); }
 
  static not_implemented_exception for_projected(const Geometry &g) {
    return not_implemented_exception(kProjected, g);
  }
 
  static not_implemented_exception for_projected(const Geometry &g1,
                                                 const Geometry &g2) {
    return not_implemented_exception(kProjected, g1, g2);
  }
 
  static not_implemented_exception for_non_projected(const Geometry &g) {
    switch (g.coordinate_system()) {
      default:
        assert(false);  // C++11 woes. /* purecov: inspected */
      case Coordinate_system::kCartesian:
        return not_implemented_exception(kCartesian, g);
      case Coordinate_system::kGeographic:
        return not_implemented_exception(kGeographic, g);
    }
  }
 
  static not_implemented_exception for_non_projected(const Geometry &g1,
                                                     const Geometry &g2) {
    switch (g1.coordinate_system()) {
      default:
        assert(false);  // C++11 woes. /* purecov: inspected */
      case Coordinate_system::kCartesian:
        return not_implemented_exception(kCartesian, g1, g2);
      case Coordinate_system::kGeographic:
        return not_implemented_exception(kGeographic, g1, g2);
    }
  }
};
 
/// NULL value exception.
///
/// Thrown when the functor discovers that the result is NULL. Normally, NULL
/// returns can be detected before calling the functor, but not always.
class null_value_exception : public std::exception {};
 
/// The base class of all functors that takes two geometry arguments.
///
/// Subclasses of this functor base class will implement operator() and call
/// apply() to do type combination dispatching. The actual body of the functor
/// is in the eval() member function, which must be implemented for each
/// different parameter type combination.
///
/// The functor may throw exceptions.
///
/// @tparam T The return type of the functor.
template <typename T>
class Functor {
 public:
  virtual T operator()(const Geometry *g1, const Geometry *g2) const = 0;
  virtual ~Functor() = default;
 
 protected:
  template <typename F>
  static inline T apply(F &f, const Geometry *g1, const Geometry *g2) {
    assert(g1->coordinate_system() == g2->coordinate_system());
    switch (g1->coordinate_system()) {
      case Coordinate_system::kCartesian:
        switch (g1->type()) {
          case Geometry_type::kPoint:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Cartesian_point *>(g1),
                              down_cast<const Cartesian_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Cartesian_point *>(g1),
                              down_cast<const Cartesian_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Cartesian_point *>(g1),
                              down_cast<const Cartesian_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Cartesian_point *>(g1),
                    down_cast<const Cartesian_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Cartesian_point *>(g1),
                              down_cast<const Cartesian_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(down_cast<const Cartesian_point *>(g1),
                              down_cast<const Cartesian_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Cartesian_point *>(g1),
                              down_cast<const Cartesian_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kLinestring:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Cartesian_linestring *>(g1),
                              down_cast<const Cartesian_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Cartesian_linestring *>(g1),
                              down_cast<const Cartesian_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Cartesian_linestring *>(g1),
                              down_cast<const Cartesian_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Cartesian_linestring *>(g1),
                    down_cast<const Cartesian_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Cartesian_linestring *>(g1),
                              down_cast<const Cartesian_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(down_cast<const Cartesian_linestring *>(g1),
                              down_cast<const Cartesian_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Cartesian_linestring *>(g1),
                              down_cast<const Cartesian_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kPolygon:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Cartesian_polygon *>(g1),
                              down_cast<const Cartesian_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Cartesian_polygon *>(g1),
                              down_cast<const Cartesian_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Cartesian_polygon *>(g1),
                              down_cast<const Cartesian_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Cartesian_polygon *>(g1),
                    down_cast<const Cartesian_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Cartesian_polygon *>(g1),
                              down_cast<const Cartesian_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(down_cast<const Cartesian_polygon *>(g1),
                              down_cast<const Cartesian_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Cartesian_polygon *>(g1),
                              down_cast<const Cartesian_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kGeometrycollection:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(
                    down_cast<const Cartesian_geometrycollection *>(g1),
                    down_cast<const Cartesian_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(
                    down_cast<const Cartesian_geometrycollection *>(g1),
                    down_cast<const Cartesian_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(
                    down_cast<const Cartesian_geometrycollection *>(g1),
                    down_cast<const Cartesian_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Cartesian_geometrycollection *>(g1),
                    down_cast<const Cartesian_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(
                    down_cast<const Cartesian_geometrycollection *>(g1),
                    down_cast<const Cartesian_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(
                    down_cast<const Cartesian_geometrycollection *>(g1),
                    down_cast<const Cartesian_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(
                    down_cast<const Cartesian_geometrycollection *>(g1),
                    down_cast<const Cartesian_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kMultipoint:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Cartesian_multipoint *>(g1),
                              down_cast<const Cartesian_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Cartesian_multipoint *>(g1),
                              down_cast<const Cartesian_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Cartesian_multipoint *>(g1),
                              down_cast<const Cartesian_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Cartesian_multipoint *>(g1),
                    down_cast<const Cartesian_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Cartesian_multipoint *>(g1),
                              down_cast<const Cartesian_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(down_cast<const Cartesian_multipoint *>(g1),
                              down_cast<const Cartesian_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Cartesian_multipoint *>(g1),
                              down_cast<const Cartesian_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kMultilinestring:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Cartesian_multilinestring *>(g1),
                              down_cast<const Cartesian_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Cartesian_multilinestring *>(g1),
                              down_cast<const Cartesian_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Cartesian_multilinestring *>(g1),
                              down_cast<const Cartesian_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Cartesian_multilinestring *>(g1),
                    down_cast<const Cartesian_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Cartesian_multilinestring *>(g1),
                              down_cast<const Cartesian_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(down_cast<const Cartesian_multilinestring *>(g1),
                              down_cast<const Cartesian_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Cartesian_multilinestring *>(g1),
                              down_cast<const Cartesian_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kMultipolygon:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Cartesian_multipolygon *>(g1),
                              down_cast<const Cartesian_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Cartesian_multipolygon *>(g1),
                              down_cast<const Cartesian_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Cartesian_multipolygon *>(g1),
                              down_cast<const Cartesian_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Cartesian_multipolygon *>(g1),
                    down_cast<const Cartesian_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Cartesian_multipolygon *>(g1),
                              down_cast<const Cartesian_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(down_cast<const Cartesian_multipolygon *>(g1),
                              down_cast<const Cartesian_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Cartesian_multipolygon *>(g1),
                              down_cast<const Cartesian_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          default:
            assert(false); /* purecov: inspected */
            throw not_implemented_exception::for_non_projected(*g1, *g2);
        }  // switch (g1->type())
      case Coordinate_system::kGeographic:
        switch (g1->type()) {
          case Geometry_type::kPoint:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Geographic_point *>(g1),
                              down_cast<const Geographic_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Geographic_point *>(g1),
                              down_cast<const Geographic_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Geographic_point *>(g1),
                              down_cast<const Geographic_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Geographic_point *>(g1),
                    down_cast<const Geographic_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Geographic_point *>(g1),
                              down_cast<const Geographic_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(
                    down_cast<const Geographic_point *>(g1),
                    down_cast<const Geographic_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Geographic_point *>(g1),
                              down_cast<const Geographic_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kLinestring:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Geographic_linestring *>(g1),
                              down_cast<const Geographic_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Geographic_linestring *>(g1),
                              down_cast<const Geographic_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Geographic_linestring *>(g1),
                              down_cast<const Geographic_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Geographic_linestring *>(g1),
                    down_cast<const Geographic_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Geographic_linestring *>(g1),
                              down_cast<const Geographic_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(
                    down_cast<const Geographic_linestring *>(g1),
                    down_cast<const Geographic_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Geographic_linestring *>(g1),
                              down_cast<const Geographic_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kPolygon:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Geographic_polygon *>(g1),
                              down_cast<const Geographic_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Geographic_polygon *>(g1),
                              down_cast<const Geographic_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Geographic_polygon *>(g1),
                              down_cast<const Geographic_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Geographic_polygon *>(g1),
                    down_cast<const Geographic_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Geographic_polygon *>(g1),
                              down_cast<const Geographic_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(
                    down_cast<const Geographic_polygon *>(g1),
                    down_cast<const Geographic_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Geographic_polygon *>(g1),
                              down_cast<const Geographic_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kGeometrycollection:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(
                    down_cast<const Geographic_geometrycollection *>(g1),
                    down_cast<const Geographic_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(
                    down_cast<const Geographic_geometrycollection *>(g1),
                    down_cast<const Geographic_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(
                    down_cast<const Geographic_geometrycollection *>(g1),
                    down_cast<const Geographic_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Geographic_geometrycollection *>(g1),
                    down_cast<const Geographic_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(
                    down_cast<const Geographic_geometrycollection *>(g1),
                    down_cast<const Geographic_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(
                    down_cast<const Geographic_geometrycollection *>(g1),
                    down_cast<const Geographic_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(
                    down_cast<const Geographic_geometrycollection *>(g1),
                    down_cast<const Geographic_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kMultipoint:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Geographic_multipoint *>(g1),
                              down_cast<const Geographic_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Geographic_multipoint *>(g1),
                              down_cast<const Geographic_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Geographic_multipoint *>(g1),
                              down_cast<const Geographic_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Geographic_multipoint *>(g1),
                    down_cast<const Geographic_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Geographic_multipoint *>(g1),
                              down_cast<const Geographic_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(
                    down_cast<const Geographic_multipoint *>(g1),
                    down_cast<const Geographic_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Geographic_multipoint *>(g1),
                              down_cast<const Geographic_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kMultilinestring:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Geographic_multilinestring *>(g1),
                              down_cast<const Geographic_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Geographic_multilinestring *>(g1),
                              down_cast<const Geographic_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Geographic_multilinestring *>(g1),
                              down_cast<const Geographic_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Geographic_multilinestring *>(g1),
                    down_cast<const Geographic_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Geographic_multilinestring *>(g1),
                              down_cast<const Geographic_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(
                    down_cast<const Geographic_multilinestring *>(g1),
                    down_cast<const Geographic_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Geographic_multilinestring *>(g1),
                              down_cast<const Geographic_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          case Geometry_type::kMultipolygon:
            switch (g2->type()) {
              case Geometry_type::kPoint:
                return f.eval(down_cast<const Geographic_multipolygon *>(g1),
                              down_cast<const Geographic_point *>(g2));
              case Geometry_type::kLinestring:
                return f.eval(down_cast<const Geographic_multipolygon *>(g1),
                              down_cast<const Geographic_linestring *>(g2));
              case Geometry_type::kPolygon:
                return f.eval(down_cast<const Geographic_multipolygon *>(g1),
                              down_cast<const Geographic_polygon *>(g2));
              case Geometry_type::kGeometrycollection:
                return f.eval(
                    down_cast<const Geographic_multipolygon *>(g1),
                    down_cast<const Geographic_geometrycollection *>(g2));
              case Geometry_type::kMultipoint:
                return f.eval(down_cast<const Geographic_multipolygon *>(g1),
                              down_cast<const Geographic_multipoint *>(g2));
              case Geometry_type::kMultilinestring:
                return f.eval(
                    down_cast<const Geographic_multipolygon *>(g1),
                    down_cast<const Geographic_multilinestring *>(g2));
              case Geometry_type::kMultipolygon:
                return f.eval(down_cast<const Geographic_multipolygon *>(g1),
                              down_cast<const Geographic_multipolygon *>(g2));
              default:
                assert(false); /* purecov: inspected */
                throw not_implemented_exception::for_non_projected(*g1, *g2);
            }
          default:
            assert(false); /* purecov: inspected */
            throw not_implemented_exception::for_non_projected(*g1, *g2);
        }  // switch (g1->type())
    }      // switch (g1->coordinate_system())
 
    assert(false); /* purecov: inspected */
    throw not_implemented_exception::for_non_projected(*g1, *g2);
  }
};
 
/// The base class of all functors that take one geometry argument.
///
/// Subclasses of this functor base class will implement operator() and call
/// apply() to do type combination dispatching. The actual body of the functor
/// is in the eval() member function, which must be implemented for each
/// different parameter type combination.
///
/// The functor may throw exceptions.
///
/// @tparam T The return type of the functor.
template <typename T>
class Unary_functor {
 public:
  virtual T operator()(const Geometry &) const = 0;
  virtual ~Unary_functor() = default;
 
 protected:
  template <class F>
  static inline T apply(F &f, const Geometry &g) {
    switch (g.coordinate_system()) {
      case Coordinate_system::kCartesian: {
        switch (g.type()) {
          case Geometry_type::kPoint:
            return f.eval(down_cast<const Cartesian_point &>(g));
          case Geometry_type::kLinestring:
            return f.eval(down_cast<const Cartesian_linestring &>(g));
          case Geometry_type::kPolygon:
            return f.eval(down_cast<const Cartesian_polygon &>(g));
          case Geometry_type::kGeometrycollection:
            return f.eval(down_cast<const Cartesian_geometrycollection &>(g));
          case Geometry_type::kMultipoint:
            return f.eval(down_cast<const Cartesian_multipoint &>(g));
          case Geometry_type::kMultilinestring:
            return f.eval(down_cast<const Cartesian_multilinestring &>(g));
          case Geometry_type::kMultipolygon:
            return f.eval(down_cast<const Cartesian_multipolygon &>(g));
          default:
            assert(false); /* purecov: inspected */
            // We don't know here whether the geometry is Cartesan or projected.
            // Assume Cartesian. This is dead code anyway.
            throw not_implemented_exception::for_non_projected(g);
        }
      }
      case Coordinate_system::kGeographic: {
        switch (g.type()) {
          case Geometry_type::kPoint:
            return f.eval(down_cast<const Geographic_point &>(g));
          case Geometry_type::kLinestring:
            return f.eval(down_cast<const Geographic_linestring &>(g));
          case Geometry_type::kPolygon:
            return f.eval(down_cast<const Geographic_polygon &>(g));
          case Geometry_type::kGeometrycollection:
            return f.eval(down_cast<const Geographic_geometrycollection &>(g));
          case Geometry_type::kMultipoint:
            return f.eval(down_cast<const Geographic_multipoint &>(g));
          case Geometry_type::kMultilinestring:
            return f.eval(down_cast<const Geographic_multilinestring &>(g));
          case Geometry_type::kMultipolygon:
            return f.eval(down_cast<const Geographic_multipolygon &>(g));
          default:
            assert(false); /* purecov: inspected */
            // We don't know here whether the geometry is Cartesan or projected.
            // Assume Cartesian. This is dead code anyway.
            throw not_implemented_exception::for_non_projected(g);
        }
      }
    }
    assert(false); /* purecov: inspected */
    // We don't know here whether the geometry is Cartesan or projected.
    // Assume Cartesian. This is dead code anyway.
    throw not_implemented_exception::for_non_projected(g);
  }
};
 
}  // namespace gis
 
#endif  // SQL_GIS_FUNCTOR_H_INCLUDED