AggregateStructUID.hpp

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#pragma once
#include "StringHash.hpp"
#include <boost/pfr.hpp>
 
namespace Cori {
    namespace Utility {
        namespace Internal {
            template<typename T>
            consteval std::string_view GetTypeHelper() {
                return __PRETTY_FUNCTION__;
            }
 
            template<typename T, typename Tuple, std::size_t... Indexes>
            consteval auto GenerateTypeSignature(std::index_sequence<Indexes...>) {
                constexpr size_t finalSize =
                    GetTypeHelper<T>().size() + 1 +
                    ((GetTypeHelper<std::tuple_element_t<Indexes, Tuple>>().size() + 1) + ...) +
                    (sizeof...(Indexes) > 0 ? -1 : 0) + 1 + 1;
 
                std::array<char, finalSize> signature{};
 
                char* cursor = signature.data();
                auto append = [&](const std::string_view sv) {
                    for (const char c : sv) {
                        *cursor++ = c;
                    }
                };
 
                append(GetTypeHelper<T>());
                append("{");
                ((append(GetTypeHelper<std::tuple_element_t<Indexes, Tuple>>()), append(Indexes == sizeof...(Indexes) - 1 ? "" : ",")), ...);
                append("}");
                *cursor = '\0';
                return signature;
            }
 
            template<typename T>
            consteval auto GetTypeSignature() {
                static_assert(std::is_aggregate_v<T>, "Type must be an aggregate.");
 
                using MemberTuple = decltype(boost::pfr::structure_to_tuple(std::declval<T>()));
                constexpr size_t memberCount = std::tuple_size_v<MemberTuple>;
 
                return Internal::GenerateTypeSignature<T, MemberTuple>(std::make_index_sequence<memberCount>());
            }
        }

        template<typename T>
        consteval uint64_t GetAggregateStructUID() {
            constexpr auto signature = Internal::GetTypeSignature<T>();
            const auto view = std::string_view(signature.data(), signature.size() - 1);
            return fnv1a64(view.data(), view.size());
        }
 
    }
}