hash_combine + usage in caching IntrospectionData

Author: Erfan-Ahmadi

include/nbl/asset/utils/CSPIRVIntrospector.h

@@ -174,7 +174,18 @@ class NBL_API2 CSPIRVIntrospector : public core::Uncopyable
 
 		struct KeyHasher
 		{
-			std::size_t operator()(const SIntrospectionParams& t) const { return 0; /*TODO*/ }
+			size_t operator()(const SIntrospectionParams& param) const 
+			{
+				auto stringViewHasher = std::hash<std::string_view>();
+
+				auto code = std::string_view(reinterpret_cast<const char*>(param.cpuShader->getContent()->getPointer()), param.cpuShader->getContent()->getSize());
+				size_t hash = stringViewHasher(code);
+
+				core::hash_combine<std::string_view>(hash, std::string_view(param.entryPoint));
+				core::hash_combine<uint32_t>(hash, static_cast<uint32_t>(param.cpuShader->getStage()));
+
+				return hash;
+			}
 		};
 
 		using ParamsToDataMap = core::unordered_map<SIntrospectionParams,core::smart_refctd_ptr<const CIntrospectionData>, KeyHasher>;

include/nbl/core/algorithm/utility.h

@@ -22,6 +22,13 @@ inline void for_each_in_tuple(std::tuple<Ts...> const& t, F f)
     impl::for_each(t, f, std::make_index_sequence<N>());
 }
 
+template <class T>
+inline void hash_combine(std::size_t& seed, const T& v)
+{
+    std::hash<T> hasher;
+    seed ^= hasher(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+}
+
 }
 }