Class Approx

CvPlot/ext/catch2/inc/catch.hpp:3032–3130

namespace Detail {

    class Approx {
    private:
        bool equalityComparisonImpl(double other) const;
        // Validates the new margin (margin >= 0)
        // out-of-line to avoid including stdexcept in the header
        void setMargin(double margin);
        // Validates the new epsilon (0 < epsilon < 1)
        // out-of-line to avoid including stdexcept in the header
        void setEpsilon(double epsilon);

    public:
        explicit Approx ( double value );

        static Approx custom();

        Approx operator-() const;

        template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
        Approx operator()( T const& value ) {
            Approx approx( static_cast<double>(value) );
            approx.m_epsilon = m_epsilon;
            approx.m_margin = m_margin;
            approx.m_scale = m_scale;
            return approx;
        }

        template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
        explicit Approx( T const& value ): Approx(static_cast<double>(value))
        {}

        template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
        friend bool operator == ( const T& lhs, Approx const& rhs ) {
            auto lhs_v = static_cast<double>(lhs);
            return rhs.equalityComparisonImpl(lhs_v);
        }

        template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
        friend bool operator == ( Approx const& lhs, const T& rhs ) {
            return operator==( rhs, lhs );
        }

        template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
        friend bool operator != ( T const& lhs, Approx const& rhs ) {
            return !operator==( lhs, rhs );
        }

        template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
        friend bool operator != ( Approx const& lhs, T const& rhs ) {
            return !operator==( rhs, lhs );
        }

        template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
        friend bool operator <= ( T const& lhs, Approx const& rhs ) {
            return static_cast<double>(lhs) < rhs.m_value || lhs == rhs;
        }

        template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
        friend bool operator <= ( Approx const& lhs, T const& rhs ) {