Color.h

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// -*- lsst-c++ -*-
/*
 * Capture the colour of an object
 */
 
#ifndef LSST_AFW_IMAGE_COLOR_H
#define LSST_AFW_IMAGE_COLOR_H
 
#include <cmath>
#include <limits>
 
namespace lsst {
namespace afw {
namespace image {
 
class Color final {
public:
    explicit Color(double g_r = std::numeric_limits<double>::quiet_NaN()) : _g_r(g_r) {}
 
    Color(Color const &) = default;
    Color(Color &&) = default;
    Color &operator=(Color const &) = default;
    Color &operator=(Color &&) = default;
    ~Color() noexcept = default;
 
    bool isIndeterminate() const noexcept { return std::isnan(_g_r); }
 
 
    bool operator==(Color const &other) const noexcept {
        return (isIndeterminate() && other.isIndeterminate()) || other._g_r == _g_r;
    }
    bool operator!=(Color const &other) const noexcept { return !operator==(other); }
 
    std::size_t hash_value() const noexcept { return isIndeterminate() ? 42 : std::hash<double>()(_g_r); }
 
private:
    double _g_r;
};
}  // namespace image
}  // namespace afw
}  // namespace lsst
 
namespace std {
template <>
struct hash<lsst::afw::image::Color> {
    using argument_type = lsst::afw::image::Color;
    using result_type = size_t;
    size_t operator()(argument_type const &obj) const noexcept { return obj.hash_value(); }
};
}  // namespace std
 
#endif