From bb53f18dfdfc6013237468dfabd92af4547346fd Mon Sep 17 00:00:00 2001
From: ADAM David Alan Martin <adam@recursive.engineer>
Date: Tue, 10 Oct 2023 02:23:22 -0400
Subject: [PATCH] This is just the rudiments of a more comprehensive
 `function_traits` design.

It's good for many common cases, but it should handle member functions and
discriminate between `std::function` objects and builtins.  It's mostly
just boilerplate to do that.
---
 function_traits.h | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 function_traits.h

diff --git a/function_traits.h b/function_traits.h
new file mode 100644
index 0000000..736104e
--- /dev/null
+++ b/function_traits.h
@@ -0,0 +1,47 @@
+static_assert( __cplusplus > 2020'00 );
+
+#pragma once
+
+#include <tuple>
+#include <type_traits>
+#include <functional>
+
+namespace Alepha::inline Cavorite  ::detail::  function_traits_module
+{
+	inline namespace exports
+	{
+		template< typename Function > struct function_traits;
+
+		template< typename Function >
+		using get_args_t= typename function_traits< Function >::args_type;
+
+		template< typename Function, int index >
+		using get_arg_t= std::decay_t< std::tuple_element_t< index, get_args_t< Function > > >;
+	}
+
+	// General catchall...
+	template< typename Function >
+	struct exports::function_traits
+		: exports::function_traits< std::decay_t< decltype( std::function( std::declval< Function >() ) ) > >
+	{};
+
+	template< typename Result, typename ... Args, bool noexceptness >
+	struct exports::function_traits< std::function< Result ( Args... ) noexcept( noexceptness ) > >
+	{
+		static constexpr bool noexcepted= noexceptness;
+		using function_type= std::function< Result ( Args... ) noexcept( noexceptness ) >;
+		using member_type= std::false_type;
+		using const_member_type= std::false_type;
+
+		using args_type= std::tuple< Args... >;
+		static constexpr std::size_t args_size= sizeof...( Args );
+
+		using return_type= Result;
+		using signature_type= Result( Args... );
+	};
+}
+
+namespace Alepha::Cavorite::inline exports::inline function_traits_module
+{
+	using namespace detail::function_traits_module::exports;
+}