Merge pull request #105 from OpenVicProject/add/ordered-map

1 files changed, 48 insertions, 0 deletions

diff --git a/src/openvic-simulation/utility/Utility.hpp b/src/openvic-simulation/utility/Utility.hpp
index e8d7205..0387e7f 100644
--- a/src/openvic-simulation/utility/Utility.hpp
+++ b/src/openvic-simulation/utility/Utility.hpp
@@ -1,5 +1,9 @@
 #pragma once
 
+#include <climits>
+#include <functional>
+#include <type_traits>
+
 namespace OpenVic::utility {
 	[[noreturn]] inline void unreachable() {
 		// Uses compiler specific extensions if possible.
@@ -11,4 +15,48 @@ namespace OpenVic::utility {
 		__assume(false);
 #endif
 	}
+
+	template<class T>
+	constexpr inline void hash_combine(std::size_t& s, const T& v) {
+		std::hash<T> h;
+		s ^= h(v) + 0x9e3779b9 + (s << 6) + (s >> 2);
+	}
+
+	template<size_t Shift, class T>
+	constexpr inline void hash_combine_index(std::size_t& s, const T& v) {
+		std::hash<T> h;
+		if constexpr(Shift == 0) {
+			s = h(v);
+		} else {
+			s ^= h(v) << Shift;
+		}
+	}
+
+	template<class T, typename ...Args>
+	constexpr void perfect_hash(std::size_t& s, T&& v, Args&&... args) {
+		static_assert(sizeof(T) + (sizeof(Args) + ...) <= sizeof(std::size_t), "Perfect hashes must be able to fit into size_t");
+		std::hash<T> h;
+		if constexpr(sizeof...(args) == 0) {
+			s = h(v);
+		} else {
+			const std::tuple arg_tuple { args... };
+			s = h(v) << (sizeof(T) * CHAR_BIT);
+			([&]{
+				// If args is not last pointer of args
+				if (static_cast<const void*>(&(std::get<sizeof...(args) - 1>(arg_tuple))) != static_cast<const void*>(&args)) {
+					s <<= sizeof(Args) * CHAR_BIT;
+				}
+				s |= std::hash<Args>{}(args);
+			}(), ...);
+		}
+	}
+
+	template<typename T, template<typename...> class Z>
+	struct is_specialization_of : std::false_type {};
+
+	template<typename... Args, template<typename...> class Z>
+	struct is_specialization_of<Z<Args...>, Z> : std::true_type {};
+
+	template<typename T, template<typename...> class Z>
+	inline constexpr bool is_specialization_of_v = is_specialization_of<T, Z>::value;
 }