1 files changed, 117 insertions, 0 deletions
diff --git a/src/openvic-simulation/types/FunctionRef.hpp b/src/openvic-simulation/types/FunctionRef.hpp
new file mode 100644
index 0000000..1ca5bb7
--- /dev/null
+++ b/src/openvic-simulation/types/FunctionRef.hpp
@@ -0,0 +1,117 @@
+#pragma once
+
+#include <functional>
+#include <type_traits>
+#include <utility>
+
+#include "openvic-simulation/types/AnyRef.hpp"
+
+namespace OpenVic {
+	// Based on https://github.com/think-cell/think-cell-library/blob/b9c84dd7fc926fad80829ed49705fa51afe36e87/tc/base/ref.h
+	//     Boost Software License - Version 1.0 - August 17th, 2003
+
+	// Permission is hereby granted, free of charge, to any person or organization
+	// obtaining a copy of the software and accompanying documentation covered by
+	// this license (the "Software") to use, reproduce, display, distribute,
+	// execute, and transmit the Software, and to prepare derivative works of the
+	// Software, and to permit third-parties to whom the Software is furnished to
+	// do so, all subject to the following:
+
+	// The copyright notices in the Software and this entire statement, including
+	// the above license grant, this restriction and the following disclaimer,
+	// must be included in all copies of the Software, in whole or in part, and
+	// all derivative works of the Software, unless such copies or derivative
+	// works are solely in the form of machine-executable object code generated by
+	// a source language processor.
+
+	// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+	// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+	// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+	// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+	// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+	// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+	// DEALINGS IN THE SOFTWARE.
+	template<bool bNoExcept, typename Ret, typename... Args>
+	struct FunctionRefBase {
+		template<bool bNoExcept2, typename Ret2, typename... Args2>
+		using type_erased_function_ptr = Ret2 (*)(AnyRef, Args2...) noexcept(bNoExcept2);
+
+		template<bool bNoExcept2, typename Func, typename Ret2, typename... Args2>
+		struct make_type_erased_function_ptr final {
+			type_erased_function_ptr<bNoExcept2, Ret2, Args2...> operator()() const& noexcept {
+				return [](AnyRef anyref,
+						  Args2... args) noexcept(bNoExcept2) -> Ret2 { // implicit cast of stateless lambda to function pointer
+					return std::invoke(
+						anyref.template get_ref<Func>(), std::forward<Args2>(args)...
+					); // MAYTHROW unless bNoExcept
+				};
+			}
+		};
+
+		template<bool bNoExcept2, typename Func, typename... Args2>
+		struct make_type_erased_function_ptr<bNoExcept2, Func, void, Args2...> final {
+			type_erased_function_ptr<bNoExcept2, void, Args2...> operator()() const& noexcept {
+				return [](AnyRef anyref,
+						  Args2... args) noexcept(bNoExcept2) { // implicit cast of stateless lambda to function pointer
+					std::invoke(anyref.template get_ref<Func>(), std::forward<Args2>(args)...); // MAYTHROW unless bNoExcept
+				};
+			}
+		};
+
+		template<typename T>
+		[[nodiscard]] static constexpr T& as_lvalue(T&& t) noexcept {
+			return t;
+		}
+
+		FunctionRefBase(FunctionRefBase const&) noexcept = default;
+
+		Ret operator()(Args... args) const& noexcept(bNoExcept) {
+			return m_pfuncTypeErased(m_anyref, std::forward<Args>(args)...); // MAYTHROW unless bNoExcept
+		}
+
+
+		template<typename Derived, typename Base>
+		struct decayed_derived_from : std::bool_constant<std::derived_from<typename std::decay<Derived>::type, Base>> {
+			static_assert(std::same_as<std::decay_t<Base>, Base>);
+		};
+
+		template<typename Func>
+		requires(!decayed_derived_from<Func, FunctionRefBase>::value) &&
+					std::invocable<std::remove_reference_t<Func>&, Args...> &&
+					(std::convertible_to<
+						 decltype(std::invoke(std::declval<std::remove_reference_t<Func>&>(), std::declval<Args>()...)), Ret> ||
+					 std::is_void<Ret>::value)
+		FunctionRefBase(Func&& func) noexcept
+			: m_pfuncTypeErased(make_type_erased_function_ptr<bNoExcept, std::remove_reference_t<Func>, Ret, Args...> {}()),
+			  m_anyref(as_lvalue(func)) {
+			static_assert(
+				!std::is_member_function_pointer<Func>::value,
+				"Raw member functions are not supported (how would you call them?).  Pass in a lambda or use "
+				"std::mem_fn instead."
+			);
+			static_assert(!std::is_pointer<Func>::value, "Pass in functions rather than function pointers.");
+			// Checking the noexcept value of the function call is commented out because MAYTHROW is widely used in generic code
+			// such as for_each, range_adaptor... static_assert(!bNoExcept ||
+			// noexcept(std::declval<tc::decay_t<Func>&>()(std::declval<Args>()...)));
+		}
+
+	private:
+		type_erased_function_ptr<bNoExcept, Ret, Args...> m_pfuncTypeErased;
+		AnyRef m_anyref;
+	};
+
+	template<typename Sig>
+	struct FunctionRef;
+
+	template<typename Ret, typename... Args>
+	struct FunctionRef<Ret(Args...)> : FunctionRefBase</*bNoExcept*/ false, Ret, Args...> {
+		using base_ = typename FunctionRef::FunctionRefBase;
+		using base_::base_;
+	};
+
+	template<typename Ret, typename... Args>
+	struct FunctionRef<Ret(Args...) noexcept> : FunctionRefBase</*bNoExcept*/ true, Ret, Args...> {
+		using base_ = typename FunctionRef::FunctionRefBase;
+		using base_::base_;
+	};
+}