Add a NamedOperator facility to Alepha.

This permits naming operators via an enhanced enum and then
looking them up.  This is a useful component for quick
scripting language functionalities.

Utility/CMakeLists.txt

@@ -4,3 +4,4 @@ target_sources( alepha PRIVATE
 
 add_subdirectory( derived_pointer_cast.test )
 add_subdirectory( print_number.test )
+add_subdirectory( NamedOperator.test )

Utility/NamedOperator.h

@@ -0,0 +1,64 @@
+static_assert( __cplusplus > 2023'00 );
+
+#pragma once
+
+#include <Alepha/Alepha.h>
+
+#include <map>
+#include <functional>
+#include <type_traits>
+
+#include <Alepha/Enum.h>
+
+namespace Alepha::Hydrogen::Utility  ::detail::  NamedOperator_m
+{
+	inline namespace exports
+	{
+		using OperatorName= Enum
+		<
+			"add"_value,
+			"sub"_value,
+			"mul"_value,
+			"mod"_value,
+			"idiv"_value
+		>;
+
+	}
+
+	struct comparator
+	{
+		constexpr auto
+		operator () ( const OperatorName &lhs, const OperatorName &rhs ) const
+		{
+			return lhs.get_index() < rhs.get_index();
+		}
+	};
+
+	namespace exports
+	{
+		template< typename Type >
+		auto
+		getOperatorMap()
+		{
+			std::map< OperatorName, std::function< Type ( Type, Type ) >, comparator > rv
+			{
+				{ "add"_value, std::plus<>{} },
+				{ "sub"_value, std::minus<>{} },
+				{ "mul"_value, std::multiplies<>{} },
+				{ "mod"_value, std::modulus<>{} },
+			};
+
+			if constexpr( std::is_integral_v< Type > )
+			{
+				rv[ "idiv"_value ]= std::divides<>{};
+			}
+
+			return rv;
+		};
+	}
+}
+
+namespace Alepha::Hydrogen::Utility::inline exports::inline NamedOperator_m
+{
+	using namespace detail::NamedOperator_m::exports;
+}

Utility/NamedOperator.test/0.cc

@@ -0,0 +1,31 @@
+static_assert( __cplusplus > 2023'00 );
+
+#include "../NamedOperator.h"
+
+#include <Alepha/Testing/test.h>
+#include <Alepha/Testing/TableTest.h>
+
+#include <Alepha/Utility/enroll.h>
+
+static auto init= Alepha::Utility::enroll <=[]
+{
+	using namespace Alepha::Testing::exports;
+	using namespace Alepha::Utility::NamedOperator_m;
+	using namespace Alepha::literals::enum_literals;
+
+	"Does the named operator system have the expected basic functionality?"_test <= TableTest
+	<
+		[]( const int lhs, const OperatorName name, const int rhs )
+		{
+			return getOperatorMap< int >().at( name )( lhs, rhs );
+		}
+	>
+	::Cases
+	{
+		{ "addition", { 1, "add"_value, 1 }, 2 },
+		{ "subtraction", { 1, "sub"_value, 1 }, 0 },
+		{ "multiplication", { 5, "mul"_value, 5 }, 25 },
+		{ "modulus", { 9, "mod"_value, 5 }, 4 },
+		{ "division", { 5, "idiv"_value, 3 }, 1 },
+	};
+};

Utility/NamedOperator.test/CMakeLists.txt

@@ -0,0 +1 @@
+unit_test( 0 )