Add Fastor library

noarch/include/Fastor/tensor_algebra/indicial.h

@@ -0,0 +1,66 @@
+#ifndef INDICIAL_H
+#define INDICIAL_H
+
+#include "Fastor/config/config.h"
+#include "Fastor/meta/einsum_meta.h"
+#include <array>
+
+namespace Fastor {
+
+//-----------------------------------------------------------------------------------------------------------//
+template <FASTOR_INDEX ... All>
+struct Index {
+    static constexpr FASTOR_INDEX Size = sizeof...(All);
+    static constexpr std::array<FASTOR_INDEX,sizeof...(All)> values = {All...};
+};
+
+template<FASTOR_INDEX ... All>
+constexpr FASTOR_INDEX Index<All...>::Size;
+
+template<FASTOR_INDEX ... All>
+constexpr std::array<FASTOR_INDEX,sizeof...(All)> Index<All...>::values;
+
+namespace internal {
+template<FASTOR_INDEX N, class seq>
+struct make_index_impl;
+template<FASTOR_INDEX N, size_t ... ss>
+struct make_index_impl<N,std_ext::index_sequence<ss...>> {
+    using type = Index<ss...>;
+};
+} // internal
+
+template<FASTOR_INDEX N>
+struct make_index {
+    using type = typename internal::make_index_impl<N,typename std_ext::make_index_sequence<N>::type>::type;
+};
+
+template<FASTOR_INDEX N>
+using make_index_t = typename make_index<N>::type;
+
+
+template<FASTOR_INDEX ... All>
+struct OIndex : public Index<All...> {
+    static constexpr FASTOR_INDEX Size = sizeof...(All);
+    using parent_type = Index<All...>;
+};
+
+template<FASTOR_INDEX ... All>
+constexpr FASTOR_INDEX OIndex<All...>::Size;
+
+template<class Idx>
+struct to_oindex;
+template<FASTOR_INDEX ... All>
+struct to_oindex<Index<All...>>
+{
+    using type = OIndex<All...>;
+};
+
+template<class Idx>
+using to_oindex_t = typename to_oindex<Idx>::type;
+
+//-----------------------------------------------------------------------------------------------------------//
+
+} // end of namespace Fastor
+
+#endif // INDICIAL_H
+