Changed `NullException` to add optional type information. Added constexpr util::type_of<T>(), added constexpr `std::string_view` concatenation: `util::concat_str_v<std::string_view...>`, added `std::string_view util::concat_strings(auto const&...)`.

Fortune for libexopt's current commit: Future blessing − 末吉

include/array.h

@@ -0,0 +1,123 @@
+#pragma once
+
+#include <array>
+#include <utility>
+#include <memory>
+
+#include "pointer.h"
+#include "util.hh"
+
+#include "exopt.h"
+
+namespace exopt::types {
+	namespace polyarray [[gnu::visibility("internal")]] {
+
+		template<typename T, size_t N>
+		struct SizedArray;
+
+		struct UnsizedAccessor {
+			constexpr virtual ~UnsizedAccessor() = default;
+
+			constexpr virtual T* data() const noexcept =0;
+		};
+
+		template<typename T, size_t N>
+		struct SizedAccessor : virtual UnsizedAccessor {
+			//using UnsizedAccessor::UnsizedAccessor;
+			constexpr virtual ~SizedAccessor() = default;
+
+			constexpr T* data() const noexcept override final { return raw()->data(); }
+
+			[[gnu::returns_nonnull]]
+			constexpr virtual std::array<T, N>* raw() noexcept =0;
+			[[gnu::returns_nonnull]]
+			constexpr virtual std::array<T, N> const* raw() const noexcept =0;
+
+			constexpr virtual std::array<T, N>& array() & noexcept { return *raw(); }
+			constexpr virtual std::array<T, N> const& array() const& noexcept { return *raw(); }
+
+			constexpr virtual std::array<T, N>&& array() && noexcept { return std::move(*raw()); }
+			constexpr virtual std::array<T, N> const&& array() const&& noexcept { return std::move(*raw()); }
+		};
+
+		/// An `std::array<T>` with unknown compile-time size.
+		template<typename T>
+		class PolyArray : public virtual UnsizedAccessor {
+		public:
+			constexpr PolyArray() noexcept = default;
+			constexpr virtual ~PolyArray() = default;
+
+			using UnsizedAccessor::data; //constexpr virtual T* data() const noexcept =0; Inherited from UnsizedAccessor
+			constexpr virtual size_t size() const noexcept =0;
+			//TODO: std::array-like accessors based on `data()..size()`
+
+			template<size_t N>
+			constexpr std::array<T, N>* try_downcast() noexcept {
+				if consteval {
+					static_assert(size() == N, "Invalid downcast array size");
+				}
+				if (size() == N) { return static_cast<SizedAccessor<T, N>*>(accessor())->raw(); }   //reinterpret_cast<std::array<T, N>*>(unsafe_data()); } 
+				return nullptr;
+			}
+			template<size_t N>
+			constexpr std::array<T, N>&& downcast() && {
+				if(auto* nar = try_downcast()) {
+					return std::move(*nar);
+				} else throw_invalid_size();
+			}
+
+			constexpr bool empty() const noexcept { return !size(); }
+		protected:
+			[[noreturn, gnu::noinline, gnu::cold]]
+			constexpr void throw_invalid_size() {
+				std::terminate(); //TODO: throw `poly_array_size_exception`
+			}
+
+		private:
+			[[gnu::returns_nonnull]]
+			constexpr UnsizedAccessor* accessor() noexcept { return static_cast<UnsizedAccessor*>(this); }
+			[[gnu::returns_nonnull]]
+			constexpr const UnsizedAccessor* accessor() const noexcept { return static_cast<UnsizedAccessor const*>(this); }
+
+			template<size_t N>
+			[[gnu::returns_nonnull]]
+			constexpr SizedAccessor<T, N>* unsafe_cast() noexcept { return static_cast<SizedAccessor<T, N>*>(
+											static_cast<UnsizedAccessor*>(this)); }
+
+		};
+
+		template<typename T, size_t N>
+		struct SizedArray :  virtual /*XXX: Needed? since both non-virtual bases of this class have virtual base UnsizedAccessor?*/ SizedAccessor<T, N>
+				  , public PolyArray<T> {
+			[[gnu::const]]
+			constexpr size_t size() const noexcept override final { return N; }
+			//[[gnu::const, gnu::returns_nonnull]] // Unneeded, SizedAccessor implements it as raw()->data()
+			//constexpr T* data() const noexcept override final { return m_data.data(); }
+
+			constexpr SizedArray(std::array<T, N>&& m) noexcept
+				: m_data(std::move(m)) {}
+			//TODO: ctors, assign, etc.
+
+			constexpr virtual ~SizedArray() = default;
+			//TODO: operator*() decltype(auto) forwards from SizedAccessor::array()
+		protected:
+			[[gnu::returns_nonnull]]
+			constexpr std::array<T, N>* raw() noexcept override final { return std::addressof(m_data); }
+			[[gnu::returns_nonnull]]
+			constexpr std::array<T, N> const* raw() const noexcept override final { return std::addressof(m_data); }
+		private:
+			std::array<T, N> m_data;
+		};
+
+		template<typename T, size_t N>
+		constexpr std::unique_ptr<PolyArray<T>> make_unsized(std::array<T, N>&& array) noexcept {
+			auto sub = std::make_unique<SizedArray<T, N>>(std::move(array));
+			return std::unique_ptr<PolyArray<T>> { static_cast<PolyArray<T>*>(sub.release()) };
+		}
+
+		template<typename T, size_t N>
+		constexpr std::array<T, N>&& /*XXX: <- Is returning an rvalue-ref here acceptible? When is `array` dropped here? Does the caller actuall drop it or the std::move() in here...? We aren't actually assigning the move to anything at all, we're just working through rvalue-refs, so it *should* be fine...??? Fuck this language honestly... */ make_sized(std::unique_ptr<PolyArray<T>>&& array) {
+			return (*std::move(array)).downcast<T, N>();
+		}
+	}
+}

include/boxed.h

@@ -10,6 +10,7 @@
 #include "exopt.h"
 
 namespace exopt::types { namespace boxed {
+
 	template<typename T>
 	struct [[gnu::visibility("internal")]]  boxable_value_type { using type = std::conditional_t
 			<std::is_reference_v<T>
@@ -30,7 +31,7 @@ namespace exopt::types { namespace boxed {
 		requires(std::is_copy_constructible_v<T>)
 	{ if(__builtin_expect(!bool(c), false)) 
 #ifdef DEBUG
-		throw ptr::NullDerefException<T>{};
+		throw ptr::null_exception<T>{}; 
 #else
 		__builtin_unreachable(); 
 #endif
@@ -62,16 +63,17 @@ namespace exopt::types { namespace boxed {
 		{ static_cast<std::decay_t<To> &&>(from) } -> std::convertible_to<To>;
 	};
 
-	/*struct ErasedTypeDeleter { 
+	struct ErasedTypeDeleter { 
 		constexpr virtual ~ErasedTypeDeleter() = default;
 		constexpr ErasedTypeDeleter() noexcept = default;
 
 		constexpr virtual void apply_delete() = 0;
 		//TODO: See below...
-	};*/
+	};
 
 	template<polymorphic_castable<void> T>
 	constexpr auto uniq_erase_type(std::unique_ptr<T>&& from) noexcept {
+		//TODO: Overload case for `unique_ptr<T, D>` for `deleter` to apply (and contain) `D()` on back_cast()ed pointer T* instead of assuming default `delete`.
 		struct deleter final /*: public ErasedTypeDeleter XXX <- Is this useful, for unerasing the type, maybe?*/ {
 			typedef T type;
 
@@ -92,26 +94,18 @@ namespace exopt::types { namespace boxed {
 				delete static_cast<T*>(p);
 			}
 			constexpr T* back_cast(void *p) noexcept { return static_cast<T*>(p); }
-			constexpr deleter() noexcept = default;
-			constexpr deleter(deleter const&) noexcept = default;
-			constexpr deleter(deleter &&) noexcept = default;
-			constexpr deleter& operator=(deleter const&) noexcept = default;
-			constexpr deleter& operator=(deleter &&) noexcept = default;
-
-			constexpr ~deleter() noexcept = default;
+			/*constexpr deleter() noexcept = default;
+			constexpr ~deleter() noexcept = default;*/
 		};
 		return std::unique_ptr<void, deleter> {
-			// Cannot retain type information of most-derived class from this: \
+			//XXX: Cannot retain type information of most-derived class from this: \
 			dynamic_cast<void*>	
 			static_cast<void*>
 			(std::move(from).release())
 			
 		};
 	}
-	template<polymorphic_castable<void> T, typename D> requires(requires{ 
-		typename std::unique_ptr<T, D>;
-		requires(!std::is_same_v<std::unique_ptr<T, D>::deleter_type, std::unique_ptr<T>::deleter_type);
-	})
+	template<polymorphic_castable<void> T, typename D> requires(requires{ typename std::unique_ptr<T, D>; })
 	constexpr auto uniq_erase_type(std::unique_ptr<T, D>&& from) noexcept {
 		class deleter final {
 			D m_del;
@@ -133,7 +127,6 @@ namespace exopt::types { namespace boxed {
 			constexpr deleter& operator=(const deleter&) noexcept(std::is_nothrow_copy_assignable_v<D>) = default;
 			constexpr deleter& operator=(deleter&&) noexcept(std::is_nothrow_move_assignable_v<D>) = default;
 
-			constexpr ~deleter() noexcept(std::is_nothrow_destructible_v<D>) requires(std::is_trivially_destructible_v<D>) = default;
 			constexpr ~deleter() noexcept(std::is_nothrow_destructible_v<D>) {}
 		};
 		if constexpr(std::is_default_constructible_v<D>)
@@ -173,8 +166,72 @@ namespace exopt::types { namespace boxed {
 		else return static_uniq_cast(std::move(from));
 	}
 
+#if 0
+//TODO: Cannot be implemented with this method
+	constexpr bool is_boxed_value(auto const& value) noexcept {
+		return bool(dynamic_cast<ObjectBase const*>(std::addressof(value)));
+	}
+	template<typename T>
+	constexpr bool is_boxed_type() noexcept {
+		using type = std::remove_reference_t<T>;
+		constexpr type const* VALUE = nullptr;
+		return bool(dynamic_cast<ObjectBase const*>(VALUE));
+	}
+
+// We need either: Tagged pointers (XOR, bit-mangled, manual heap, or GOT (external allocation) kind), \
+	or (preferred): layout of Box<T> to be `{ aligned<T>(T, box_type_tag) } unique*` \
+		box_type_tag should be: One pointer width, starting at offset *T+1 (aligned to T within internal tuple struct), provides a way to access RTTI for `*T`, a pointer to static (non-allocated) type information or dynamic_cast used lambda would be ideal.
+#endif
+	/// Base class which is used to store the layout of Box<T>'s allocated memory. Intended for use to determine if a certain `T`'s `this` pointer is inside a `Box<T>` or not.
+	class dynamic_boxed_layout_base{
+		using Self = dynamic_boxed_layout_base;
+	public:
+		constexpr dynamic_boxed_layout_base() noexcept = default;
+		constexpr ~dynamic_boxed_layout_base() = default;
+
+		typedef void* (dynamic_cast_t)(Self*);
+		typedef const void* (dynamic_const_cast_t)(Self const*);
+
+		constexpr virtual size_t value_byte_offset() const noexcept =0;
+
+		[[gnu::returns_nonnull]]
+		constexpr void* extract_untyped_pointer() noexcept {
+			return reinterpret_cast<void*>(
+				reinterpret_cast<this>(unsigned char*) + value_byte_offset()
+			);
+		}
+		[[gnu::returns_nonnull]]
+		constexpr const void* extract_untyped_pointer() const noexcept {
+			return reinterpret_cast<void const*>(
+				reinterpret_cast<this>(const unsigned char*) + value_byte_offset()
+			);
+		}
+
+		constexpr virtual void* invoke_casting_shim(dynamic_cast_t const*) const noexcept =0;
+
+		template<typename T>
+		constexpr bool is_typeof() const noexcept { return invoke_casting_shim([] (Self* self) { return dynamic_cast<T*>(self)
+
+		template<typename T>
+		[[gnu::returns_nonnull]]
+		inline T* extract_pointer_unsafe() noexcept {
+			return reinterpret_cast<T*>(extract_untyped_pointer());
+		}
+		template<typename T>
+		[[gnu::returns_nonnull]]
+		inline const T* extract_pointer_unsafe() const noexcept {
+			return reinterpret_cast<const T*>(extract_untyped_pointer());
+		}
+
 		template<typename T>	
-	struct alignas(std::unique_ptr<T>) Box {
+		[[gnu::returns_nonnull]]
+		inline T* try_extract_pointer() noexcept {
+			return is_typeof<T>() ? extract_pointer_unsafe<T>() : nullptr;
+		}
+	};
+
+	template<typename T>
+	struct Box final {
 		typedef boxable_value_type<T>::type type;
 
 		template<std::derived_from<T> U, bool RuntimeCheck=false>
@@ -220,24 +277,15 @@ namespace exopt::types { namespace boxed {
 		}
 
 		[[gnu::nonnull(1)]]
-		constexpr static Box<T> from_raw_ptr(T* ptr) noexcept(!_EO(DEBUG)) {
-#if DEBUG
-			ptr::throw_if_null(ptr);
-#endif
+		constexpr static Box<T> from_raw_ptr(T* ptr) noexcept {
 			return Box<T>{ std::unique_ptr<T>{ ptr } };
 		}
-
-		constexpr static Box<T> from_raw_ptr(std::unique_ptr<T>&& uniq) {
-			if(__builtin_expect(!bool(uniq), false)) ptr::throw_null_exception<T>();
-			_EO_ASSUME(uniq.get() != nullptr);
-			return Box<T> { std::move(uniq) };
-		}
-
-		constexpr static Box<T> from_raw_ptr_unchecked(std::unique_ptr<T>&& uniq) noexcept(!_EO(DEBUG)) {
+		constexpr static Box<T> from_raw_ptr(std::unique_ptr<T>&& uniq) 
 #if DEBUG
-			if(__builtin_expect(!uniq, false)) ptr::throw_null_exception<T>(); 
+			{ if(__builtin_expect(!uniq, false)) throw ptr::NullException{};
 #else
 
+			noexcept {
 			_EO_ASSUME(uniq.get() != nullptr);
 #endif
 			return Box<T>{ std::move(uniq) };
@@ -252,63 +300,49 @@ namespace exopt::types { namespace boxed {
 	//TODO: Accessors, `(explicit?) operator std::unique_ptr<T> const&[&]`?, etc.
 
 		constexpr ~Box() = default;
-	protected:
-		// For types that may need to invalidate the Box<T> guarantee without exposing it in API, they can inherit (non-virtual). 
-
-		// For unsafe operations, wether or not to apply checks.
-		enum unsafe_t {
-			UNSAFE,
-		};
-		enum maybe_unsafe_t {
-			CHECKED,
-			DEBUG_CHECKED,
-		};
+	private:
+		constexpr explicit Box(std::unique_ptr<T>&& ptr)
+			: m_ptr(std::move(ptr)) {
+			_EO_ASSUME(m_ptr.get());
+		}
 
-		constexpr Box(util::exact_type<unsafe_t> auto u, std::unique_ptr<T>&& ptr) noexcept 
-			: m_ptr(std::move(ptr)) { (void)u; }
+// TODO: Identifying if a value `this` pointer is boxed
+		struct alignas(type) inner_layout_t final : public dynamic_boxed_layout_base {
+			using boxed_value_t = type;
 
-		constexpr static Box<T> from_raw_ptr(unsafe_t u, std::unique_ptr<T>&& uniq) noexcept {
-			return Box{u, std::move(uniq)};
-		}
+			constexpr inner_layout_t(type&& v) noexcept(std::is_nothrow_move_constructible_v<type>)
+				: value(std::move(v)) {}
+			//TODO: All the ctors, assigns, and operators that can make this newtype wrapper more conveniently useable as a deref-target for accessing `value`.
 			
-		constexpr std::unique_ptr<T>& as_unique(unsafe_t) & noexcept { return m_ptr; }
-		constexpr std::unique_ptr<T> const & as_unique(unsafe_t) const& noexcept { return m_ptr; }
+			constexpr /*virtual*/ ~inner_layout_t() = default;
 
-		constexpr std::unique_ptr<T>&& as_unique(unsafe_t) && noexcept { return std::move(m_ptr); }
-		constexpr std::unique_ptr<T> const&& as_unique(unsafe_t) const&& noexcept { return std::move(m_ptr); }
+			[[gnu::const]]
+			constexpr size_t value_byte_offset() const noexcept override { return offsetof(inner_layout_t, value); }
 
-		constexpr T* as_unsafe_ptr(unsafe_t) const noexcept { return m_ptr.get(); }
-		constexpr std::unique_ptr<T> swap_unsafe_ptr(unsafe_t u, T* raw) noexcept 
-		{ return (void)u; std::exchange(std::move(m_ptr), std::unique_ptr<T>{ raw }); }
-		constexpr void set_unsafe_ptr(unsafe_t 8, T* raw) noexcept { 
-			(void)u;
-			m_ptr.reset(raw);
-		}
-		constexpr decltype(auto) set_unsafe(unsafe_t u, std::unique_ptr<T>&& ptr) noexcept 
-		{ (void)u; return std::exchange(std::move(m_ptr), std::move(ptr)); }
-		constexpr auto& swap_unsafe(unsafe_t, std::unique_ptr<T>& ptr) noexcept { 
-			using std::swap;
-			swap(m_ptr, ptr);
-			return m_ptr;
-		}
+			type value;
+		};
 		
-		constexpr T* release_unsafe(unsafe_t) noexcept { return m_ptr.release(); }
-	private:
-		constexpr explicit Box(std::unique_ptr<T>&& ptr) noexcept
-			: m_ptr(std::move(ptr)) {
-			_EO_ASSUME(m_ptr.get());
-		}
+		struct inner_unique_ptr_t final {
+			std::unique_ptr<inner_layout_t>
+		};
 
-		std::unique_ptr<T> m_ptr; // Unique<T> m_ptr;
+		inner_unique_ptr_t m_ptr; // Unique<T> m_ptr;
 	};
-	static_assert(util::shares_layout<Box<_Complex double>, _Complex double*>, "Invalid Box<T> memory layout: More than just T*");
-	static_assert(util::shares_layout<Box<_Complex double>, std::unique_ptr<_Complex double>>, "Invalid Box<T> memory layout: More than just std::unique_ptr<T>");
 
+#define _EO_ADD_RV std::add_rvalue_reference_v
+
+	template<typename Base, typename T = Base>
+	constexpr inline bool is_boxable_v = binary_convertible<_EO_ADD_RV<T>, _EO_ADD_RV<Base> > and requires(T&& value) { 
+		typename Box<Base>;
+		typename Box<Base>::type;
+		{ std::make_unique<T>(std::move(value)) } -> std::same_as<std::unique_ptr<T>>;
+	};
 	template<typename T> concept is_boxable = is_boxable_v<T>;
 
 	template<typename T>
 	constexpr inline bool is_nothrow_boxable_v = is_boxable_v<T> && std::is_nothrow_constructible_v<Box<T>, T>;
 
+#undef _EO_ADD_RV
 
 	template<typename T, typename U> requires(requires(T&& o) { static_cast<U&&>(o); })
 	constexpr Box<U> static_box_cast(Box<T>&& b) noexcept { return Box<U>::from_raw_ptr(static_cast<U*>(b.release())); }
@@ -322,12 +356,7 @@ namespace exopt::types { namespace boxed {
 			delete rel;
 			throw;
 		}
-	} 
-
-	template<typename T, typename U> requires(requires(T const& o) { static_cast<U const&>(o); })
-	constexpr Box<U> dynamic_box_cast(Box<T> const& b) {
-		return Box<U>::from_raw_ptr(std::addressof(dynamic_cast<U const&>(*b)));
-	} 
+	} //TODO: Overload for `const&` that does the type check *before* the copy allocation.
 
 #if 0
 	template<typename T, typename R /*XXX: Maybe remove this, and put the requires after the definition, using `auto&& value` instead of `R&& value`*/> requires(std::derived_from<R, T>)
@@ -370,8 +399,6 @@ namespace exopt::types { namespace boxed {
 using boxed::Box;
 }
 
-//TODO: See phone notes on correctly implementing the nullopt for Box<T>
-#if 0
 namespace exopt::types { namespace optional [[gnu::visibility("internal")]] {
 	template<typename T>
 	struct null_optimise<boxed::Box<T> > { constexpr static inline bool value = true;
@@ -386,4 +413,3 @@ namespace exopt::types { namespace optional [[gnu::visibility("internal")]] {
 
 
 }
-#endif

include/exopt.h

@@ -22,36 +22,17 @@ extern "C" {
 #define _exopt__internal __attribute__((visibility("internal")))
 #define _exopt__readonly __attribute__((__pure__))
 #define _exopt__pure __attribute__((__const__))
-#ifdef DEBUG
-#	define _exopt__DEBUG 1
-#else
-#	define _exopt__DEBUG 0
-#endif
-#ifdef RELEASE
-#	define _exopt__RELEASE 1
-#else
-#	define _exopt__RELEASE 0
-#endif
 
 #ifdef _EO__OPT_OLD_ASSUME
 #	define _EO_ASSUME(X) ({ if(! (X)) __builtin_unreachable(); })
 #endif
 
-#define _EO_FIXED_INT(B) _BitInt(B)
-
-#define _EO_GNU_ATTR(...) __attribute__((__VA_ARGS__))
-
 #if _EO(cpp)
-#	define _EO_ATTR(...) [[__VA_ARGS__]]
-#	define _EO_SHARES_LAYOUT(T, U) (sizeof(T) == sizeof(U) && alignof(T) == alignof(U))
 #	ifndef _EO_ASSUME
 #		define _EO_ASSUME(X) [[gnu::assume(X)]]
 #	endif
 #	define _exopt__restrict __restrict__
-#else /* C */
-#	define _EO_ATTR(...) __attribute__((__VA_ARGS__))
-#	define _EO_SHARES_LAYOUT(T, U) (sizeof(T) == sizeof(U) && alignof(T) == alignof(U))
-#	define _EO_SHARES_LAYOUT(T, U) (sizeof(T) == sizeof(U) && _Alignof(T) == _Alignof(U))
+#else
 #	ifndef _EO_ASSUME
 #		define _EO_ASSUME(X) __attribute__((assume(X)))
 #	endif

include/optional.h

@@ -31,6 +31,8 @@ namespace exopt::types { namespace optional [[gnu::visibility("internal")]] {
 		constexpr static inline auto sentinel = nullptr;
 	};
 
+
+
 	template<typename T>
 	struct null_optimise<ptr::Unique<T> > { constexpr static inline bool value = true;
 		using held_type = T __restrict__*;

include/pointer.h

@@ -104,33 +104,6 @@ namespace exopt::ptr {
 		return std::forward<decltype(ptr)>(ptr);
 	}
 
-	template<typename E, typename... Args> requires(std::is_constructible_v<E, Args...>)
-	constexpr decltype(auto) throw_if_null(PointerEqCmp auto const& ptr, Args&&... error) {
-		auto _throw = [&] [[noreturn, gnu::noinline, gnu::cold]] () {
-			throw E{std::forward<Args>(error)...};
-		};
-		if(ptr == nullptr) _throw();
-		return std::forward<decltype(ptr)>(ptr);
-	}
-
-	
-	[[gnu::always_inline]]
-	constexpr decltype(auto) throw_if_null(PointerEqCmp auto const& ptr) {
-		if(__builtin_expect(ptr == nullptr, false)) throw_null_exception<decltype(ptr)>();
-		return std::forward<decltype(ptr)>(ptr);
-	}
-
-	// Throws NullDerefException<?> for first type of `ptr` that is null (if any are).
-	// If: `All == true`:  Instead will always throw `NullDerefException<T...> (all types) if any are, and will not assume every pointer is likely to be non-null.
-	template<bool All = false>
-	[[gnu::always_inline]]
-	constexpr void throw_if_null(PointerEqCmp auto const&... ptr) requires(sizeof...(decltype(ptr)) > 1) {
-		if constexpr(All) {
-			using E = NullDerefException<decltype(ptr)...>;
-			((void)throw_if_null<E>(std::forward<decltype(ptr)>(ptr)),...);
-		} else ((void)throw_if_null(std::forward<decltype(ptr)>(ptr)),...);
-	}
-
 	template<typename E, typename... Args> requires(std::is_constructible_v<E, Args...>)
 	constexpr decltype(auto) deref_or_throw(PointerDeref auto&& ptr, Args&&... error)
 	{
@@ -217,13 +190,6 @@ namespace exopt::ptr {
 
 	consteval NullException/*&&*/ null_exception() noexcept { return {}; }
 
-	template<typename... Types>
-	[[noreturn, gnu::noinline, gnu::cold]]
-	constexpr void throw_null_exception() { throw null_exception<Types...>(); }
-
-	[[noreturn, gnu::noinline, gnu::cold]]
-	constexpr void throw_null_exception() { throw null_exception(); }
-
 	template<typename T> requires(!std::is_reference_v<T>)
 	struct NonNull {
 

include/rng.hh

@@ -0,0 +1,53 @@
+#pragma once
+
+#include <bit>
+#include <array>
+
+#include <cstdint>
+
+#include "util.hh"
+
+#include "exopt.h"
+
+namespace exopt::rng {
+	[[gnu::visibility("internal")]]
+	constexpr inline auto COMPILED_ENTROPY{
+#if __has_include("compiled_entropy.dat")
+#embed "compiled_entropy.dat"
+#else
+	nullptr 
+#endif
+	};
+	constexpr inline auto has_compiled_entropy_v = !std::is_same_v<std::nullptr_t, decltype(COMPILED_ENTROPY)>;
+
+	// XXX: The usage of __COUNTER__ *might* work as wanted if we wrap it in _EO_CONSTANT_VALUE() and take `util::comptime<uint64_t> auto = _EO_CONSTANT_VALUE(__COUNTER__)` as default argument instead. Maybe... I don't know..
+	template<typename T = unsigned char>
+	consteval decltype(auto) comptime_rand_next() noexcept {
+		std::array<unsigned char, sizeof(T)> v;
+		for(int i=0;i<v.size();i++) v[i] = comptime_rand_next<unsigned char>();
+		return util::comptime_value(std::bit_cast<T>(std::move(v)));
+	}
+	template<>
+	consteval decltype(auto) comptime_rand_next<unsigned char>(uint64_t counter = __COUNTER__) noexcept {
+		return _EO_CONSTANT_VALUE(COMPILED_ENTROPY[counter  % sizeof(COMPILED_ENTROPY)]);
+	}
+
+	consteval uint64_t seed_linear(uint64_t counter = __COUNTER__) noexcept { return uint64_t(counter); } //XXX: This is kinda a dumb experiment, the __TIME__ TU-specific seed should be fine, but __COUNTER__ is a token evaluated regardless of calling context, so... Unless it's used before the #include<>, it'll always be the same.
+	consteval uint64_t seed_translation() noexcept { return uint64_t(__TIME__); }
+
+	
+	// Seed: __TIME__ or __COUNTER__
+	[[gnu::const]]
+	constexpr uint64_t splitmix64_once(uint64_t x) noexcept {
+		//TODO: implement splitmix64 here for constexpr/consteval contexts
+	}
+	
+	constexpr inline uint64_t translation_unit_fixed_seed = splitmit64_once(seed_translation());
+	constexpr inline uint64_t linear_fixed_seed = splitmit64_once(seed_linear()); // ODR dependant?? When is __COUNTER__ evaluated? In preprocessing, right? So, before any compilation?
+	constexpr inline auto translation_unit_rolling_seed = ([] () {
+		struct {
+			constexpr operator uint64_t() const noexcept { return splitmix64_once(translation_unit_fixed_seed ^ seed_linear()) ^ _EO_CONSTANT_VALUE(splitmix64_once(__COUNTER__)); }
+		} inner;
+		return inner;
+	})();
+}

include/util.hh

@@ -68,12 +68,6 @@ namespace exopt { namespace util [[gnu::visibility("internal")]] {
 	static_assert(_EO_CONSTANT_VALUE(std::string_view{"hello world"}) == std::string_view{"hello world"}, "Bad CONSTANT_VALUE()");
 
 
-	template<typename T, typename U>
-	concept shares_layout = sizeof(T) == sizeof(U) && alignof(T) == alignof(U);
-
-	template<typename T, typename U>
-	concept exact_type = std::is_same_v<T, U>;
-
 	template<typename T, size_t N, typename Array= std::array<T, N>, typename _I = std::make_index_sequence<N>>
 	constexpr auto array_literal(const T (&a)[N]) noexcept 
 		-> Array
@@ -184,90 +178,17 @@ namespace exopt { namespace util [[gnu::visibility("internal")]] {
 	static_assert(concat_str_v< std::string_view{"hello"}, std::string_view{" "}, std::string_view{"view"} >
 			== std::string_view{"hello view"}, "concat_str_v<>: Concatenated string_view failed");
 
-	template<template<typename> P, typename... Values>
-	struct _EO(internal) is_all_match {
-		constexpr static inline auto value = (P<Values> && true && ...);
-
-		consteval operator auto() const noexcept { return value; }
-	};
-
-	template<template<typename> P, typename... Values>
-	struct _EO(internal) is_any_match {
-		constexpr static inline auto value = (P<Values> || false || ...);
-
-		consteval operator auto() const noexcept { return value; }
-	};
-
-	//XXX: Idk if template<template<s are allowed in this context...
-	template<template<typename> P, typename... Values> requires(requires{ typename is_all_match<P, Values>; })
-	constexpr inline auto is_all_match_v = is_all_match<P, Values...>::value;
-
-	template<template<typename> P, typename... Values> requires(requires{ typename is_any_match<P, Values>; })
-	constexpr inline auto is_any_match_v = is_any_match<P, Values...>::value;
-
-	template<auto... Values>
-	struct _EO(internal) is_all {
-		constexpr static inline auto value = (Values && true && ...);
-	};
-
-	template<auto... Values>
-	struct _EO(internal) is_any {
-		constexpr static inline auto value = (Values || false || ...);
-	};
-
-	template<auto... Values>
-	constexpr inline auto is_all_v = is_all<Values...>::value;
-	template<auto... Values>
-	constexpr inline auto is_any_v = is_any<Values...>::value;
-
-	template<typename... Args>
-	constexpr inline bool is_empty_v = sizeof...(Args) == 0;
-
-	template<auto... Values> // auto and typename aren't compatible unfortunately
-	constexpr inline bool is_empty_vv = sizeof...(Values) == 0;
-
-	// Convenience immediate function overloads for checking if a parameter pack *or* a value pack is empty without different names.
-	template<typename... A>
-	consteval bool is_empty_pack() noexcept { return sizeof...(A) == 0; }
-
-	template<auto... A>
-	consteval bool is_empty_pack() noexcept { return sizeof...(A) == 0; }
-
-	///  Deducable version of `is_empty_pack<typename...>()`
-	///
-	/// Can be used as `is_empty_pack(pack...)` instead of the slightly more ugly `is_empty_pack<decltype(pack)...>()` though with (very unlikely, but possible) implications of actually "evaluating" the pack (despite the values themselves are `const&` and never used, they're still passed.) 
-	/// HOWEVER: The latter should likely be preferred, since this function takes possible-nonconstexpr types as arguments, it cannot be immediate like the non-argument taking overload. See below comment for more information on that.
-	template<typename... A>
-	[[gnu::const]] //TODO: XXX: This mostly useless function won't mess up overload resolution for `is_empty_pack<types...>()`, right? If it will, either find a way to make sure it comes LAST, or remove it, it's not worth the hassle just so users (i.e. me) can avoid typeing `decltype` for once in my fuckin life... what a stupud keyword name srsl (see static_assert() below.)
-	constexpr auto is_empty_pack(A const&...) noexcept { return is_empty_pack<A...>(); } // This overload exists for: e.g usage for index_sequence: \
-		`template<size_t N> f(const auto (&v)[N]) -> \
-		template<size_t Is...> _f(auto const& v, std::index_sequence<Is...>);`\
-		Can be used like: \
-		_f(const auto&v, std::convertible_to<size_t> auto&&... is) \
-			{ if constexpr(is_empty_pack(is...)) { ... } ... }` \
-		i.e: for unknown-typed non-type parameter packs `auto...`s packs can be `forward<decltype(pack)>(pack)...`'d (or just passed, as the taken value is always `const&`) to is_empty_pack(...) and `A...` can therefor be deduced. This is not possible for the non-value taking overloads, and also must be non-consteval since any `A` might not be constexpr. \
-\
-		It is a convenience function that is essentially equivelent to `is_empty_pack<decltype(pack)...>()`, which should be preferred, since it is consteval and will always be guaranteed to be consteval regardless of the contents of `pack` itself, but I highly doubt any compiler will actually generate any argument-passing code for this overload either.
-
-	static_assert(!is_empty_pack<int, long, float>() 
-		and is_empty_pack<>() //XXX: This might also be ambiguous between the type and value one... Eh.... That's actually useful though, so removing this explicit (and pointless) *usage* of the function from the test would be fine if they don't clash in other ways too.
-		and !is_empty_pack<0, 1, 2>()
-		and !is_empty_pack(0u, 1.0, 2l)
-		and is_empty_pack(), "`is_empty_pack()` overload issues.");
-
 	template<typename R, typename... Args>
-	constexpr auto map(auto const& fun, Args&&... values) noexcept(is_empty_v<Args...> or is_all_v<std::is_nothrow_invocable_v<decltype(fun), Args>...>)
-								requires(is_empty_v<Args...> or (is_all_v<std::is_invocable_v<decltype(fun), Args>...> and (
-			is_any_v<std::is_void_v<std::invoke_result_t<decltype(fun), Args>>...> ||
-			 std::is_constructible_v<R, std::invoke_result_t<decltype(fun), Args>...>)))
-		-> std::conditional_t< is_empty_v<Args...> || is_any_v<std::is_void_v<std::invoke_result_t<decltype(fun), Args>>...>
-					, std::void_t<std::invoke_result_t<decltype(fun), Args>...>
+	constexpr auto map(auto const& fun, Args&&... values) noexcept((std::is_nothrow_invocable_v<decltype(fun), Args> && ...))
+								requires((std::is_invocable_v<decltype(fun), Args> && ...) and (
+			(std::is_void_v<std::invoke_result_t<decltype(fun), Args>> || ...) ||
+			 std::is_constructible_v<R, std::invoke_result_t<decltype(fun), Args>...>))
+		-> std::conditional_t< (std::is_void_v<std::invoke_result_t<decltype(fun), Args>> || ...)
+					, void
 					, R>
 	{
-		if constexpr( is_any_v<std::is_void_v<std::invoke_result_t<decltype(fun), Args>>...> ) {
+		if constexpr( (std::is_void_v<std::invoke_result_t<decltype(fun), Args>> || ...) ) {
 			((void)std::invoke(fun, values),...);
-		else if constexpr(sizeof...(Args) == 0)
-			(void)0;
 		} else return { std::invoke(fun, values)... };
 	}
 
@@ -276,13 +197,6 @@ namespace exopt { namespace util [[gnu::visibility("internal")]] {
 	template<typename... Args>
 	using map_tuple = map<std::tuple<Args...>, Args...>;
 
-	//TODO: template< is_valid_metafunction_with_two_unknown_type_arguments_and_a_possibly_variable_return_type<R(T1, T2)> Op, typename... Args> \
-		auto reduce(auto const& fun, Op const& comb, Args&&... values) noexcept(...) \
-		requires(???) -> std::invoke_result_t<??????> { // TODO: Reframe the call to `comb` as an operator overload in a shim class, and use binary fold to make the call, like: ` \
-		shim s{comb}; return (s + std::invoke(fun, values) + ...); }`
-
-
-
 	template<typename Fn, typename... Args> requires((std::is_invocable_v<Fn, Args> && ...))
 	constexpr void apply(const Fn& fun, Args&&... values) noexcept((std::is_nothrow_invocable_v<Fn, Args> && ...))
 		/*-> std::conditional_t<	(std::is_void_v<std::invoke_result_t<Fn, Args>> || ...)