1 files changed, 57 insertions, 0 deletions
diff --git a/deps/tao_tuple/28626e99/include/tao/seq/type_by_index.hpp b/deps/tao_tuple/28626e99/include/tao/seq/type_by_index.hpp
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+++ b/deps/tao_tuple/28626e99/include/tao/seq/type_by_index.hpp
@@ -0,0 +1,57 @@
+// The Art of C++ / Sequences
+// Copyright (c) 2015 Daniel Frey
+
+#ifndef TAOCPP_SEQUENCES_INCLUDE_TYPE_BY_INDEX_HPP
+#define TAOCPP_SEQUENCES_INCLUDE_TYPE_BY_INDEX_HPP
+
+#include <cstddef>
+#include <type_traits>
+
+#include "make_integer_sequence.hpp"
+
+namespace tao
+{
+  namespace seq
+  {
+    // based on http://stackoverflow.com/questions/18942322
+
+    namespace impl
+    {
+      template< std::size_t >
+      struct any
+      {
+        any( ... );
+      };
+
+      template< typename >
+      struct wrapper;
+
+      template< typename >
+      struct unwrap;
+
+      template< typename T >
+      struct unwrap< wrapper< T > >
+      {
+        using type = T;
+      };
+
+      template< typename >
+      struct get_nth;
+
+      template< std::size_t... Is >
+      struct get_nth< index_sequence< Is... > >
+      {
+        template< typename T >
+        static T deduce( any< Is & 0 >..., T*, ... );
+      };
+    }
+
+    template< std::size_t I, typename... Ts >
+    using type_by_index = impl::unwrap< decltype( impl::get_nth< make_index_sequence< I > >::deduce( std::declval< impl::wrapper< Ts >* >()... ) ) >;
+
+    template< std::size_t I, typename... Ts >
+    using type_by_index_t = typename type_by_index< I, Ts... >::type;
+  }
+}
+
+#endif // TAOCPP_SEQUENCES_INCLUDE_TYPE_BY_INDEX_HPP