add compile_time_while as a different implementation of constexpr_while

Author: robertshepherdcpp

compile_time_while.hpp

@@ -0,0 +1,69 @@
+#pragma once
+
+
+#include<tuple>
+#include<utility>
+#include<cstddef>
+#include<iostream>
+
+namespace mlib
+{
+
+	template<auto start_value, auto condition_for_val, auto operation_on_val>
+	struct pack
+	{
+		constexpr auto operator()()
+		{
+			if constexpr (!condition_for_val(start_value))
+			{
+				return 0;
+			}
+			else
+			{
+				return 1 + pack<operation_on_val(start_value), condition_for_val, operation_on_val>{}();
+			}
+		}
+	};
+
+	template<auto Care, auto DontCare>
+	struct any_first
+	{
+		constexpr auto operator()()
+		{
+			return Care;
+		}
+	};
+
+	template<auto iterations, auto lambda>
+	constexpr auto make_tuple_sequence()
+	{
+		return[&]<std::size_t... indexes>(std::index_sequence<indexes...>)
+		{
+			return std::tuple{ (any_first<lambda, indexes>{}())... };
+		}(std::make_index_sequence<iterations>{});
+	}
+
+	template<typename... Ts>
+	constexpr auto for_each_lambda(std::tuple<Ts...> tup)
+	{
+		[&] <std::size_t... indexes>(std::make_index_sequence<indexes...>)
+		{
+			(std::get<indexes>(tup)(), ...);
+		}(std::make_index_sequence<sizeof...(Ts)>{});
+	}
+
+	template<auto start_value, auto condition_for_val, auto operation_on_val>
+	struct compile_time_while
+	{
+		constexpr auto operator()(auto operation_to_do)
+		{
+			// first of all, make a value that is how many times the operations are true.
+			constexpr auto amount_of_iterations = pack<start_value, condition_for_val, operation_on_val>{}();
+			// so now that we have the number of iterations, we need to make a tuple of size: amount_of_iterations
+			// and then we need to do a for_each on them! simple!
+			constexpr auto tuple_sequence = make_tuple_sequence<amount_of_iterations, operation_to_do>();
+			// now do for_each
+			for_each_lambda(tuple_sequence);
+		}
+	};
+} // namespace mlib

mlib.vcxproj

@@ -133,6 +133,7 @@
   <ItemGroup>
     <ClInclude Include="all_of.hpp" />
     <ClInclude Include="amount.hpp" />
+    <ClInclude Include="compile_time_while.hpp" />
     <ClInclude Include="constant_parameter.hpp" />
     <ClInclude Include="constexpr_for.hpp" />
     <ClInclude Include="constexpr_map.hpp" />

mlib.vcxproj.filters

@@ -147,6 +147,9 @@
     <ClInclude Include="parse_rules.hpp">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="compile_time_while.hpp">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="Main.cpp">