Add util/hash header

libs/gfx/source/renderer/deferred.cpp

@@ -20,50 +20,10 @@
 #include <psemek/cg/convex_hull_2d/graham.hpp>
 
 #include <psemek/util/to_string.hpp>
+#include <psemek/util/hash.hpp>
 
 #include <map>
-
+#include <unordered_map>
-void hash_combine(std::size_t & seed, std::size_t value)
-{
-	seed ^= value + 0x9e3779b9 + (seed<<6) + (seed>>2);
-}
-
-namespace std
-{
-
-	template <typename T1, typename T2>
-	struct hash<std::tuple<T1, T2>>
-	{
-		std::hash<T1> h1;
-		std::hash<T2> h2;
-
-		std::size_t operator() (std::tuple<T1, T2> const & t) const
-		{
-			std::size_t h = 0;
-			hash_combine(h, h1(std::get<0>(t)));
-			hash_combine(h, h2(std::get<1>(t)));
-			return h;
-		}
-	};
-
-	template <typename T1, typename T2, typename T3>
-	struct hash<std::tuple<T1, T2, T3>>
-	{
-		std::hash<T1> h1;
-		std::hash<T2> h2;
-		std::hash<T3> h3;
-
-		std::size_t operator() (std::tuple<T1, T2, T3> const & t) const
-		{
-			std::size_t h = 0;
-			hash_combine(h, h1(std::get<0>(t)));
-			hash_combine(h, h2(std::get<1>(t)));
-			hash_combine(h, h3(std::get<2>(t)));
-			return h;
-		}
-	};
-
-}
 
 namespace psemek::gfx
 {

libs/util/include/psemek/util/hash.hpp

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <functional>
+#include <tuple>
+
+namespace psemek::util
+{
+
+	// based on boost::hash_combine
+	inline void hash_combine(std::size_t & seed, std::size_t value)
+	{
+		seed ^= value + 0x9e3779b9 + (seed<<6) + (seed>>2);
+	}
+
+}
+
+namespace std
+{
+
+	template <typename ... Ts>
+	struct hash<std::tuple<Ts...>>
+		: std::tuple<std::hash<Ts>...>
+	{
+		std::size_t operator()(std::tuple<Ts...> const & t) const
+		{
+			return hash_impl(t, std::make_index_sequence<sizeof...(Ts)>{});
+		}
+
+	private:
+		template <std::size_t ... Is>
+		std::size_t hash_impl(std::tuple<Ts...> const & t, std::index_sequence<Is...>) const
+		{
+			std::size_t result = 0;
+			(::psemek::util::hash_combine(result, std::get<Is>(*this)(std::get<Is>(t))), ...);
+			return result;
+		}
+	};
+
+}