CppUtils/modules/Math/Utility.mpp at master · MorganCaron/CppUtils · GitHub

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export module CppUtils.Math.Utility;

import std;
import CppUtils.Type.Concept;

export namespace CppUtils::Math
{
	// Plus utile en C++23 (std::abs constexpr)
	[[nodiscard]] inline constexpr auto absolute(auto number) -> decltype(auto)
	{
		if constexpr (std::unsigned_integral<decltype(number)>)
			return number;
		else if constexpr (std::floating_point<decltype(number)>)
			return number < 0 ? -number : number;
		else
			return number < 0 ?
				static_cast<std::make_unsigned_t<decltype(number)>>(-number) :
				static_cast<std::make_unsigned_t<decltype(number)>>(number);
	}

	static_assert(absolute(0) == 0u);
	static_assert(absolute(1) == 1u);
	static_assert(absolute(-1) == 1u);
	static_assert(absolute(0.0) == 0.0);
	static_assert(absolute(1.5) == 1.5);
	static_assert(absolute(-1.5) == 1.5);
	static_assert(absolute(0u) == 0u);
	static_assert(absolute(1u) == 1u);

	template<std::floating_point Float>
	[[nodiscard]] inline constexpr auto isEqual(Float lhs, Float rhs, Float epsilon = std::numeric_limits<Float>::epsilon()) noexcept -> bool
	{
		auto difference = absolute(lhs - rhs);
		auto maximum = std::max(absolute(lhs), absolute(rhs));
		if (maximum >= Float{1})
			return difference <= epsilon * maximum;
		else if (maximum > Float{0})
			return difference / maximum <= epsilon;
		return true;
	}

	static_assert(isEqual(0.0, 0.0));
	static_assert(isEqual(0.1 + 0.2, 0.3));
	static_assert(not isEqual(0.1 + 0.2, 0.29));
	static_assert(not isEqual(0.1 + 0.2, 0.31));

	template<Type::Numeric T>
	[[nodiscard]] inline constexpr auto isBetween(T value, T low, T high) noexcept -> bool
	{
		return low <= value and value <= high;
	}

	static_assert(isBetween(5, 0, 10));
	static_assert(not isBetween(-5, 0, 10));
	static_assert(not isBetween(15, 0, 10));
	static_assert(isBetween(5.0, 0.0, 10.0));
	static_assert(not isBetween(-5.0, 0.0, 10.0));
	static_assert(not isBetween(15.0, 0.0, 10.0));
	static_assert(isBetween(5.0f, 0.0f, 10.0f));
	static_assert(not isBetween(-5.0f, 0.0f, 10.0f));
	static_assert(not isBetween(15.0f, 0.0f, 10.0f));
}