coordinate.hpp

/*

Copyright (c) 2017, Project OSRM contributors
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*/

#ifndef OSRM_UTIL_COORDINATE_HPP_
#define OSRM_UTIL_COORDINATE_HPP_

#include "util/alias.hpp"

#include <boost/numeric/conversion/cast.hpp>

#include <cstdint>
#include <type_traits>

namespace osrm
{

constexpr const double COORDINATE_PRECISION = 1e6;

namespace util
{

namespace tag
{
struct latitude
{
};
struct longitude
{
};
struct unsafelatitude
{
};
struct unsafelongitude
{
};
} // namespace tag

// Internal lon/lat types - assumed to be range safe
using FixedLatitude = Alias<std::int32_t, tag::latitude>;
using FixedLongitude = Alias<std::int32_t, tag::longitude>;
using FloatLatitude = Alias<double, tag::latitude>;
using FloatLongitude = Alias<double, tag::longitude>;
// Types used for external input data - conversion functions perform extra
// range checks on these (toFixed/toFloat, etc)
using UnsafeFloatLatitude = Alias<double, tag::unsafelatitude>;
using UnsafeFloatLongitude = Alias<double, tag::unsafelongitude>;
static_assert(std::is_standard_layout<FixedLatitude>() && std::is_trivial<FixedLatitude>(),
              "FixedLatitude is not a valid alias");
static_assert(std::is_standard_layout<FixedLongitude>() && std::is_trivial<FixedLongitude>(),
              "FixedLongitude is not a valid alias");
static_assert(std::is_standard_layout<FloatLatitude>() && std::is_trivial<FloatLatitude>(),
              "FloatLatitude is not a valid alias");
static_assert(std::is_standard_layout<FloatLongitude>() && std::is_trivial<FloatLongitude>(),
              "FloatLongitude is not a valid alias");
static_assert(std::is_standard_layout<UnsafeFloatLatitude>() &&
                  std::is_trivial<UnsafeFloatLatitude>(),
              "UnsafeFloatLatitude is not a valid alias");
static_assert(std::is_standard_layout<UnsafeFloatLongitude>() &&
                  std::is_trivial<UnsafeFloatLongitude>(),
              "UnsafeFloatLongitude is not a valid alias");

/**
 * Converts a typed latitude from floating to fixed representation.
 *
 * \param floating typed latitude in floating representation.
 * \return typed latitude in fixed representation
 * \see Coordinate, toFloating
 */
inline FixedLatitude toFixed(const FloatLatitude floating)
{
    const auto latitude = static_cast<double>(floating);
    const auto fixed = static_cast<std::int32_t>(std::round(latitude * COORDINATE_PRECISION));
    return FixedLatitude{fixed};
}

/**
 * Converts a typed latitude from floating to fixed representation.  Also performs an overflow check
 * to ensure that the value fits inside the fixed representation.
 *
 * \param floating typed latitude in floating representation.
 * \return typed latitude in fixed representation
 * \see Coordinate, toFloating
 */
inline FixedLatitude toFixed(const UnsafeFloatLatitude floating)
{
    const auto latitude = static_cast<double>(floating);
    const auto fixed =
        boost::numeric_cast<std::int32_t>(std::round(latitude * COORDINATE_PRECISION));
    return FixedLatitude{fixed};
}

/**
 * Converts a typed longitude from floating to fixed representation.
 *
 * \param floating typed longitude in floating representation.
 * \return typed latitude in fixed representation
 * \see Coordinate, toFloating
 */
inline FixedLongitude toFixed(const FloatLongitude floating)
{
    const auto longitude = static_cast<double>(floating);
    const auto fixed = static_cast<std::int32_t>(std::round(longitude * COORDINATE_PRECISION));
    return FixedLongitude{fixed};
}

/**
 * Converts a typed longitude from floating to fixed representation.  Also performns an overflow
 * check to ensure that the value fits inside the fixed representation.
 *
 * \param floating typed longitude in floating representation.
 * \return typed latitude in fixed representation
 * \see Coordinate, toFloating
 */
inline FixedLongitude toFixed(const UnsafeFloatLongitude floating)
{
    const auto longitude = static_cast<double>(floating);
    const auto fixed =
        boost::numeric_cast<std::int32_t>(std::round(longitude * COORDINATE_PRECISION));
    return FixedLongitude{fixed};
}

/**
 * Converts a typed latitude from fixed to floating representation.
 *
 * \param fixed typed latitude in fixed representation.
 * \return typed latitude in floating representation
 * \see Coordinate, toFixed
 */
inline FloatLatitude toFloating(const FixedLatitude fixed)
{
    const auto latitude = static_cast<std::int32_t>(fixed);
    const auto floating = static_cast<double>(latitude) / COORDINATE_PRECISION;
    return FloatLatitude{floating};
}

/**
 * Converts a typed longitude from fixed to floating representation.
 *
 * \param fixed typed longitude in fixed representation.
 * \return typed longitude in floating representation
 * \see Coordinate, toFixed
 */
inline FloatLongitude toFloating(const FixedLongitude fixed)
{
    const auto longitude = static_cast<std::int32_t>(fixed);
    const auto floating = static_cast<double>(longitude) / COORDINATE_PRECISION;
    return FloatLongitude{floating};
}

// fwd. decl.
struct FloatCoordinate;

/**
 * Represents a coordinate based on longitude and latitude in fixed representation.
 *
 * To prevent accidental longitude and latitude flips, we provide typed longitude and latitude
 * wrappers. You can cast these wrappers back to their underlying representation or convert them
 * from one representation to the other.
 *
 * The two representation we provide are:
 *  - Fixed point
 *  - Floating point
 *
 * \see FloatCoordinate, toFixed, toFloating
 */
struct Coordinate
{
    FixedLongitude lon;
    FixedLatitude lat;

    Coordinate() : lon{std::numeric_limits<int>::min()}, lat{std::numeric_limits<int>::min()} {}

    Coordinate(const FloatCoordinate &other);

    Coordinate(const FloatLongitude lon_, const FloatLatitude lat_)
        : Coordinate(toFixed(lon_), toFixed(lat_))
    {
    }

    Coordinate(const UnsafeFloatLongitude lon_, const UnsafeFloatLatitude lat_)
        : Coordinate(toFixed(lon_), toFixed(lat_))
    {
    }

    Coordinate(const FixedLongitude lon_, const FixedLatitude lat_) : lon(lon_), lat(lat_) {}

    template <class T> Coordinate(const T &coordinate) : lon(coordinate.lon), lat(coordinate.lat)
    {
        static_assert(!std::is_same<T, Coordinate>::value,
                      "This constructor should not be used for Coordinates");
        static_assert(std::is_same<decltype(lon), decltype(coordinate.lon)>::value,
                      "coordinate types incompatible");
        static_assert(std::is_same<decltype(lat), decltype(coordinate.lat)>::value,
                      "coordinate types incompatible");
    }

    bool IsValid() const;
    friend bool operator==(const Coordinate lhs, const Coordinate rhs);
    friend bool operator!=(const Coordinate lhs, const Coordinate rhs);
};

/**
 * Represents a coordinate based on longitude and latitude in floating representation.
 *
 * To prevent accidental longitude and latitude flips, we provide typed longitude and latitude
 * wrappers. You can cast these wrappers back to their underlying representation or convert them
 * from one representation to the other.
 *
 * The two representation we provide are:
 *  - Fixed point
 *  - Floating point
 *
 * \see Coordinate, toFixed, toFloating
 */
struct FloatCoordinate
{
    FloatLongitude lon;
    FloatLatitude lat;

    FloatCoordinate()
        : lon{std::numeric_limits<double>::min()}, lat{std::numeric_limits<double>::min()}
    {
    }

    FloatCoordinate(const Coordinate other)
        : FloatCoordinate(toFloating(other.lon), toFloating(other.lat))
    {
    }

    FloatCoordinate(const FixedLongitude lon_, const FixedLatitude lat_)
        : FloatCoordinate(toFloating(lon_), toFloating(lat_))
    {
    }

    FloatCoordinate(const FloatLongitude lon_, const FloatLatitude lat_) : lon(lon_), lat(lat_) {}

    bool IsValid() const;
    friend bool operator==(const FloatCoordinate lhs, const FloatCoordinate rhs);
    friend bool operator!=(const FloatCoordinate lhs, const FloatCoordinate rhs);
};

bool operator==(const Coordinate lhs, const Coordinate rhs);
bool operator==(const FloatCoordinate lhs, const FloatCoordinate rhs);

inline Coordinate::Coordinate(const FloatCoordinate &other)
    : Coordinate(toFixed(other.lon), toFixed(other.lat))
{
}
} // namespace util
} // namespace osrm

#endif /* COORDINATE_HPP_ */