Change colour_t to be a strongly typed structure

Make RGB default of `colour_t`
Distinguish RGB and ARGB colors by type and colour_traits
Add `_colour` and `_argb` colour user-defined literals
Add `OpenVic::utility::unreachable`

1 files changed, 415 insertions, 26 deletions

diff --git a/src/openvic-simulation/types/Colour.hpp b/src/openvic-simulation/types/Colour.hpp
index 7c97b12..dc9c4c6 100644
--- a/src/openvic-simulation/types/Colour.hpp
+++ b/src/openvic-simulation/types/Colour.hpp
@@ -1,42 +1,431 @@
 #pragma once
 
 #include <algorithm>
+#include <array>
+#include <cassert>
+#include <charconv>
+#include <climits>
+#include <cmath>
+#include <compare>
 #include <cstdint>
 #include <iomanip>
+#include <limits>
+#include <span>
 #include <sstream>
 #include <string>
+#include <string_view>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+#include "openvic-simulation/utility/Getters.hpp"
+#include "openvic-simulation/utility/Utility.hpp"
 
 namespace OpenVic {
+	template<typename ValueT, typename IntT>
+	struct colour_traits {
+		using value_type = ValueT;
+		using integer_type = IntT;
+		static_assert(sizeof(value_type) * 4 <= sizeof(integer_type), "value_type must be 4x smaller then colour_integer_type");
+
+		/* When colour_t is used as an identifier, NULL_COLOUR is disallowed
+		 * and should be reserved as an error value.
+		 * When colour_t is used in a purely graphical context, NULL_COLOUR
+		 * should be allowed.
+		 */
+		static constexpr integer_type null = 0;
+		static constexpr integer_type component = std::numeric_limits<ValueT>::max();
+		static constexpr integer_type component_bit_size = sizeof(ValueT) * CHAR_BIT;
+		static constexpr integer_type blue_shift = 0;
+		static constexpr integer_type green_shift = component_bit_size;
+		static constexpr integer_type red_shift = component_bit_size * 2;
+		static constexpr integer_type alpha_shift = component_bit_size * 3;
+		static constexpr bool has_alpha = true;
+
+		static constexpr integer_type make_rgb_integer(value_type red, value_type green, value_type blue) {
+			return (red << red_shift) | (green << green_shift) | (blue << blue_shift);
+		}
+		static constexpr integer_type make_argb_integer(value_type red, value_type green, value_type blue, value_type alpha) {
+			return make_rgb_integer(red, green, blue) | (alpha << alpha_shift);
+		}
+
+		static constexpr value_type red_from_integer(integer_type colour) {
+			return (colour >> red_shift) & component;
+		}
+		static constexpr value_type blue_from_integer(integer_type colour) {
+			return (colour >> blue_shift) & component;
+		}
+		static constexpr value_type green_from_integer(integer_type colour) {
+			return (colour >> green_shift) & component;
+		}
+		static constexpr value_type alpha_from_integer(integer_type colour) {
+			return (colour >> alpha_shift) & component;
+		}
+
+		static constexpr float component_to_float(value_type value) {
+			return static_cast<float>(value) / static_cast<float>(component);
+		}
+
+		static constexpr value_type component_from_float(float f, float min = 0.0f, float max = 1.0f) {
+			constexpr auto floor = [](float f) {
+				const std::int64_t i = static_cast<std::int64_t>(f);
+				return f < i ? i - 1 : i;
+			};
+
+			return floor(std::clamp(min + f * (max - min), min, max) * static_cast<float>(component));
+		}
+
+		static constexpr value_type component_from_fraction(int n, int d, float min = 0.0f, float max = 1.0f) {
+			return component_from_float(static_cast<float>(n) / static_cast<float>(d), min, max);
+		}
+
+		static constexpr float red_to_float(value_type red) {
+			return component_to_float(red);
+		}
+		static constexpr float green_to_float(value_type green) {
+			return component_to_float(green);
+		}
+		static constexpr float blue_to_float(value_type blue) {
+			return component_to_float(blue);
+		}
+		static constexpr float alpha_to_float(value_type alpha) {
+			return component_to_float(alpha);
+		}
+
+		static constexpr value_type red_from_float(float red) {
+			return component_from_float(red);
+		}
+		static constexpr value_type green_from_float(float green) {
+			return component_from_float(green);
+		}
+		static constexpr value_type blue_from_float(float blue) {
+			return component_from_float(blue);
+		}
+		static constexpr value_type alpha_from_float(float alpha) {
+			return component_from_float(alpha);
+		}
+
+		static constexpr integer_type max_rgb = make_rgb_integer(component, component, component);
+		static constexpr integer_type max_argb = make_argb_integer(component, component, component, component);
+	};
+
 	/* Colour represented by an unsigned integer, either 24-bit RGB or 32-bit ARGB. */
-	using colour_t = uint32_t;
-
-	/* When colour_t is used as an identifier, NULL_COLOUR is disallowed
-	 * and should be reserved as an error value.
-	 * When colour_t is used in a purely graphical context, NULL_COLOUR
-	 * should be allowed.
-	 */
-	static constexpr colour_t NULL_COLOUR = 0, COLOUR_COMPONENT = 0xFF;
-	static constexpr colour_t MAX_COLOUR_RGB = 0xFFFFFF, MAX_COLOUR_ARGB = 0xFFFFFFFF;
-
-	constexpr colour_t float_to_colour_byte(float f, float min = 0.0f, float max = 1.0f) {
-		return static_cast<colour_t>(std::clamp(min + f * (max - min), min, max) * 255.0f);
-	}
+	template<typename ValueT, typename ColourIntT, typename ColourTraits = colour_traits<ValueT, ColourIntT>>
+	struct basic_colour_t : ReturnByValueProperty {
+		using colour_traits = ColourTraits;
+		using value_type = typename colour_traits::value_type;
+		using integer_type = typename colour_traits::integer_type;
 
-	constexpr colour_t fraction_to_colour_byte(int n, int d, float min = 0.0f, float max = 1.0f) {
-		return float_to_colour_byte(static_cast<float>(n) / static_cast<float>(d), min, max);
-	}
+		static_assert(std::same_as<ValueT, value_type> && std::same_as<ColourIntT, integer_type>);
 
-	constexpr colour_t float_to_alpha_value(float a) {
-		return float_to_colour_byte(a) << 24;
-	}
+		static constexpr auto max_value = colour_traits::component;
 
-	constexpr float colour_byte_to_float(colour_t colour) {
-		return std::clamp(static_cast<float>(colour) / 255.0f, 0.0f, 1.0f);
-	}
+		struct empty_value {
+			constexpr empty_value() {}
+			constexpr empty_value(value_type) {}
+			constexpr operator value_type() const {
+				return max_value;
+			}
+		};
+
+	private:
+		using _alpha_t = std::conditional_t<colour_traits::has_alpha, value_type, empty_value>;
+
+	public:
+		value_type red;
+		value_type green;
+		value_type blue;
+		[[no_unique_address]] _alpha_t alpha;
+
+		static constexpr std::integral_constant<std::size_t, std::is_same_v<decltype(alpha), value_type> ? 4 : 3> size = {};
+
+		static constexpr basic_colour_t fill_as(value_type value) {
+			if constexpr (colour_traits::has_alpha) {
+				return { value, value, value, value };
+			} else {
+				return { value, value, value };
+			}
+		}
+
+		static constexpr basic_colour_t null() {
+			return fill_as(colour_traits::null);
+		}
+
+		static constexpr basic_colour_t from_integer(integer_type integer) {
+			if constexpr (colour_traits::has_alpha) {
+				return { colour_traits::red_from_integer(integer), colour_traits::green_from_integer(integer),
+						 colour_traits::blue_from_integer(integer), colour_traits::alpha_from_integer(integer) };
+			} else {
+				assert(
+					colour_traits::alpha_from_integer(integer) == colour_traits::null ||
+					colour_traits::alpha_from_integer(integer) == max_value
+				);
+				return { colour_traits::red_from_integer(integer), colour_traits::green_from_integer(integer),
+						 colour_traits::blue_from_integer(integer) };
+			}
+		}
+
+		static constexpr basic_colour_t
+		from_floats(float r, float g, float b, float a = colour_traits::alpha_to_float(max_value))
+		requires(colour_traits::has_alpha)
+		{
+			return { colour_traits::red_from_float(r), colour_traits::green_from_float(g), colour_traits::blue_from_float(b),
+					 colour_traits::alpha_from_float(a) };
+		}
+
+		static constexpr basic_colour_t from_floats(float r, float g, float b)
+		requires(!colour_traits::has_alpha)
+		{
+			return { colour_traits::red_from_float(r), colour_traits::green_from_float(g), colour_traits::blue_from_float(b) };
+		}
+
+		constexpr integer_type as_rgb() const {
+			return colour_traits::make_rgb_integer(red, green, blue);
+		}
+
+		constexpr integer_type as_argb() const {
+			return colour_traits::make_argb_integer(red, green, blue, alpha);
+		}
+
+		constexpr basic_colour_t() : basic_colour_t { null() } {}
+
+		constexpr basic_colour_t(value_type r, value_type g, value_type b, value_type a = max_value)
+		requires(colour_traits::has_alpha)
+			: red(r), green(g), blue(b), alpha(a) {}
+
+		constexpr basic_colour_t(value_type r, value_type g, value_type b)
+		requires(!colour_traits::has_alpha)
+			: red(r), green(g), blue(b) {}
+
+		template<typename _ColourTraits>
+		requires(_ColourTraits::has_alpha && std::same_as<typename _ColourTraits::value_type, value_type> && std::same_as<typename _ColourTraits::integer_type, integer_type>)
+		explicit constexpr basic_colour_t(basic_colour_t<value_type, integer_type, _ColourTraits> const& colour)
+		requires(colour_traits::has_alpha)
+			: basic_colour_t { colour.red, colour.green, colour.blue, colour.alpha } {}
+
+		template<typename _ColourTraits>
+		requires(!_ColourTraits::has_alpha && std::same_as<typename _ColourTraits::value_type, value_type> && std::same_as<typename _ColourTraits::integer_type, integer_type>)
+		explicit constexpr basic_colour_t(
+			basic_colour_t<value_type, integer_type, _ColourTraits> const& colour, value_type a = max_value
+		)
+		requires(colour_traits::has_alpha)
+			: basic_colour_t { colour.red, colour.green, colour.blue, a } {}
+
+		template<typename _ColourTraits>
+		requires(std::same_as<typename _ColourTraits::value_type, value_type> && std::same_as<typename _ColourTraits::integer_type, integer_type>)
+		explicit constexpr basic_colour_t(basic_colour_t<value_type, integer_type, _ColourTraits> const& colour)
+		requires(!colour_traits::has_alpha)
+			: basic_colour_t { colour.red, colour.green, colour.blue } {}
+
+		constexpr explicit operator integer_type() const {
+			if constexpr (colour_traits::has_alpha) {
+				return as_argb();
+			} else {
+				return as_rgb();
+			}
+		}
 
-	inline std::string colour_to_hex_string(colour_t colour, bool alpha = false) {
-		std::ostringstream stream;
-		stream << std::uppercase << std::hex << std::setfill('0') << std::setw(!alpha ? 6 : 8) << colour;
-		return stream.str();
+		constexpr basic_colour_t with_red(value_type r) const {
+			if constexpr (colour_traits::has_alpha) {
+				return { r, green, blue, alpha };
+			} else {
+				return { r, green, blue };
+			}
+		}
+
+		constexpr basic_colour_t with_green(value_type g) const {
+			if constexpr (colour_traits::has_alpha) {
+				return { red, g, blue, alpha };
+			} else {
+				return { red, g, blue };
+			}
+		}
+
+		constexpr basic_colour_t with_blue(value_type b) const {
+			if constexpr (colour_traits::has_alpha) {
+				return { red, green, b, alpha };
+			} else {
+				return { red, green, b };
+			}
+		}
+
+		constexpr basic_colour_t with_alpha(value_type a) const
+		requires(colour_traits::has_alpha)
+		{
+			return { red, green, blue, a };
+		}
+
+		constexpr float redf() const {
+			return colour_traits::red_to_float(red);
+		}
+
+		constexpr float greenf() const {
+			return colour_traits::green_to_float(green);
+		}
+
+		constexpr float bluef() const {
+			return colour_traits::blue_to_float(blue);
+		}
+
+		constexpr float alphaf() const {
+			return colour_traits::alpha_to_float(alpha);
+		}
+
+		inline std::string to_hex_string(bool alpha = false) const {
+			using namespace std::string_view_literals;
+			static constexpr std::string_view digits = "0123456789ABCDEF"sv;
+			static constexpr std::size_t bits_per_digit = 4;
+			static constexpr std::size_t digit_mask = (1 << bits_per_digit) - 1;
+			static constexpr std::size_t argb_length = colour_traits::component_bit_size / bits_per_digit * 4;
+			static constexpr std::size_t rgb_length = colour_traits::component_bit_size / bits_per_digit * 3;
+
+			const std::size_t length = alpha ? argb_length : rgb_length;
+			std::array<char, argb_length> address;
+			const integer_type value = alpha ? as_argb() : as_rgb();
+
+			for (std::size_t index = 0, j = (length - 1) * bits_per_digit; index < length; ++index, j -= bits_per_digit) {
+				address[index] = digits[(value >> j) & digit_mask];
+			}
+			return { address.data(), length };
+		}
+
+		explicit operator std::string() const {
+			return to_hex_string(colour_traits::has_alpha);
+		}
+
+		friend std::ostream& operator<<(std::ostream& stream, basic_colour_t const& colour) {
+			return stream << colour.operator std::string();
+		}
+
+		constexpr bool is_null() const {
+			return *this == null();
+		}
+
+		constexpr auto operator<=>(basic_colour_t const& rhs) const = default;
+		constexpr auto operator<=>(integer_type rhs) const {
+			return operator integer_type() <=> rhs;
+		}
+
+		constexpr value_type& operator[](std::size_t index) {
+			return _array_access_helper<value_type>(*this, index);
+		}
+
+		constexpr const value_type& operator[](std::size_t index) const {
+			return _array_access_helper<const value_type>(*this, index);
+		}
+
+	private:
+		template<typename V, typename T>
+		static constexpr V& _array_access_helper(T& t, std::size_t index) {
+			switch (index) {
+			case 0: return t.red;
+			case 1: return t.green;
+			case 2: return t.blue;
+			}
+			if constexpr (size() == 4) {
+				if (index == 3) {
+					return t.alpha;
+				}
+				assert(index < 4);
+			} else {
+				assert(index < 3);
+			}
+			/* Segfault if index is out of bounds and NDEBUG is defined! */
+			OpenVic::utility::unreachable();
+		}
+
+	public:
+		template<std::size_t Index>
+		auto&& get() & {
+			return get_helper<Index>(*this);
+		}
+
+		template<std::size_t Index>
+		auto&& get() && {
+			return get_helper<Index>(*this);
+		}
+
+		template<std::size_t Index>
+		auto&& get() const& {
+			return get_helper<Index>(*this);
+		}
+
+		template<std::size_t Index>
+		auto&& get() const&& {
+			return get_helper<Index>(*this);
+		}
+
+	private:
+		template<std::size_t Index, typename T>
+		static auto&& get_helper(T&& t) {
+			static_assert(Index < size(), "Index out of bounds for OpenVic::basic_colour_t");
+			if constexpr (Index == 0) {
+				return std::forward<T>(t).red;
+			}
+			if constexpr (Index == 1) {
+				return std::forward<T>(t).green;
+			}
+			if constexpr (Index == 2) {
+				return std::forward<T>(t).blue;
+			}
+			if constexpr (Index == 3) {
+				return std::forward<T>(t).alpha;
+			}
+		}
+	};
+
+	template<typename T>
+	concept IsColour = requires(T t) {
+		{ basic_colour_t { t } } -> std::same_as<T>;
+	};
+
+	template<typename ValueT, typename IntT>
+	struct rgb_colour_traits : colour_traits<ValueT, IntT> {
+		static constexpr bool has_alpha = false;
+	};
+
+	using colour_argb_t = basic_colour_t<std::uint8_t, std::uint32_t>;
+	using colour_rgb_t = basic_colour_t<std::uint8_t, std::uint32_t, rgb_colour_traits<std::uint8_t, std::uint32_t>>;
+
+	using colour_t = colour_rgb_t;
+
+	namespace colour_literals {
+		constexpr colour_t operator""_colour(unsigned long long value) {
+			return colour_t::from_integer(value);
+		}
+
+		constexpr colour_argb_t operator""_argb(unsigned long long value) {
+			return colour_argb_t::from_integer(value);
+		}
 	}
 }
+
+namespace std {
+	template<typename ValueT, typename ColourIntT, typename ColourTraits>
+	struct tuple_size<::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>>
+		: integral_constant<size_t, ::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>::size()> {};
+
+	template<size_t Index, typename ValueT, typename ColourIntT, typename ColourTraits>
+	struct tuple_element<Index, ::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>> {
+		using type = decltype(::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>::red);
+	};
+	template<typename ValueT, typename ColourIntT, typename ColourTraits>
+	struct tuple_element<1, ::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>> {
+		using type = decltype(::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>::green);
+	};
+	template<typename ValueT, typename ColourIntT, typename ColourTraits>
+	struct tuple_element<2, ::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>> {
+		using type = decltype(::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>::blue);
+	};
+	template<typename ValueT, typename ColourIntT, typename ColourTraits>
+	struct tuple_element<3, ::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>> {
+		using type = decltype(::OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>::alpha);
+	};
+
+	template<typename ValueT, typename ColourIntT, typename ColourTraits>
+	struct hash<OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits>> {
+		size_t operator()(OpenVic::basic_colour_t<ValueT, ColourIntT, ColourTraits> const& s) const noexcept {
+			return hash<decltype(s.as_argb())> {}(s.as_argb());
+		}
+	};
+}