From db1b0edff3649304871479e7dd33250dce381603 Mon Sep 17 00:00:00 2001
From: ADAM David Alan Martin <adam@pyp-e.io>
Date: Fri, 12 Jul 2024 14:55:03 -0400
Subject: [PATCH] Add named comparator support.

---
 Utility/CMakeLists.txt                      |  1 +
 Utility/NamedComparator.h                   | 61 +++++++++++++++++++++
 Utility/NamedComparator.test/0.cc           | 46 ++++++++++++++++
 Utility/NamedComparator.test/CMakeLists.txt |  1 +
 4 files changed, 109 insertions(+)
 create mode 100644 Utility/NamedComparator.h
 create mode 100644 Utility/NamedComparator.test/0.cc
 create mode 100644 Utility/NamedComparator.test/CMakeLists.txt

diff --git a/Utility/CMakeLists.txt b/Utility/CMakeLists.txt
index 6d3634f..6410db3 100644
--- a/Utility/CMakeLists.txt
+++ b/Utility/CMakeLists.txt
@@ -5,3 +5,4 @@ target_sources( alepha PRIVATE
 add_subdirectory( derived_pointer_cast.test )
 add_subdirectory( print_number.test )
 add_subdirectory( NamedOperator.test )
+add_subdirectory( NamedComparator.test )
diff --git a/Utility/NamedComparator.h b/Utility/NamedComparator.h
new file mode 100644
index 0000000..2de3bf3
--- /dev/null
+++ b/Utility/NamedComparator.h
@@ -0,0 +1,61 @@
+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::  NamedComparator_m
+{
+	inline namespace exports
+	{
+		using ComparatorName= Enum
+		<
+			"eq"_value,
+			"ne"_value,
+			"lt"_value,
+			"gt"_value,
+			"le"_value,
+			"ge"_value
+		>;
+	}
+
+	struct comparator
+	{
+		constexpr auto
+		operator () ( const ComparatorName &lhs, const ComparatorName &rhs ) const
+		{
+			return lhs.get_index() < rhs.get_index();
+		}
+	};
+
+	namespace exports
+	{
+		template< typename Type >
+		auto
+		getComparatorMap()
+		{
+			std::map< ComparatorName, std::function< bool ( Type, Type ) >, comparator > rv
+			{
+				{ "eq"_value, std::equal_to<>{} },
+				{ "ne"_value, std::not_equal_to<>{} },
+				{ "lt"_value, std::less<>{} },
+				{ "gt"_value, std::greater<>{} },
+				{ "le"_value, std::less_equal<>{} },
+				{ "ge"_value, std::greater_equal<>{} },
+			};
+
+			return rv;
+		};
+	}
+}
+
+namespace Alepha::Hydrogen::Utility::inline exports::inline NamedComparator_m
+{
+	using namespace detail::NamedComparator_m::exports;
+}
diff --git a/Utility/NamedComparator.test/0.cc b/Utility/NamedComparator.test/0.cc
new file mode 100644
index 0000000..2773236
--- /dev/null
+++ b/Utility/NamedComparator.test/0.cc
@@ -0,0 +1,46 @@
+static_assert( __cplusplus > 2023'00 );
+
+#include "../NamedComparator.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::NamedComparator_m;
+	using namespace Alepha::literals::enum_literals;
+
+	"Does the named comparator system have the expected basic functionality?"_test <= TableTest
+	<
+		[]( const int lhs, const ComparatorName name, const int rhs )
+		{
+			return getComparatorMap< int >().at( name )( lhs, rhs );
+		}
+	>
+	::Cases
+	{
+		{ "equals (true)", { 1, "eq"_value, 1 }, true },
+		{ "equals (false)", { 1, "eq"_value, 2 }, false },
+
+		{ "not equals (true)", { 1, "ne"_value, 2 }, true },
+		{ "not equals (false)", { 1, "ne"_value, 1 }, false },
+
+		{ "less (true)", { 1, "lt"_value, 2 }, true },
+		{ "less (false)", { 1, "lt"_value, 1 }, false },
+
+		{ "greater (true)", { 2, "gt"_value, 1 }, true },
+		{ "greater (false)", { 1, "gt"_value, 1 }, false },
+
+
+		{ "less equal (true)", { 1, "le"_value, 2 }, true },
+		{ "less equal (true)", { 1, "le"_value, 1 }, true },
+		{ "less equal (false)", { 1, "le"_value, 0 }, false },
+
+		{ "greater equal (true)", { 2, "ge"_value, 1 }, true },
+		{ "greater equal (true)", { 1, "ge"_value, 1 }, true },
+		{ "greater equal (false)", { 0, "ge"_value, 1 }, false },
+	};
+};
diff --git a/Utility/NamedComparator.test/CMakeLists.txt b/Utility/NamedComparator.test/CMakeLists.txt
new file mode 100644
index 0000000..b099603
--- /dev/null
+++ b/Utility/NamedComparator.test/CMakeLists.txt
@@ -0,0 +1 @@
+unit_test( 0 )