Tidy up core sources:

The core headers are moved to their own directory (but remain in
the same namespace).

include/beast/core/detail/integer_sequence.hpp

@@ -0,0 +1,145 @@
+//
+// Copyright (c) 2013-2016 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BEAST_DETAIL_INTEGER_SEQUENCE_H_INCLUDED
+#define BEAST_DETAIL_INTEGER_SEQUENCE_H_INCLUDED
+
+#include <cstddef>
+#include <type_traits>
+#include <utility>
+
+namespace beast {
+namespace detail {
+
+template<class T, T... Ints>
+struct integer_sequence
+{
+    using value_type = T;
+    static_assert (std::is_integral<T>::value,
+        "std::integer_sequence can only be instantiated with an integral type" );
+
+    static std::size_t constexpr static_size = sizeof...(Ints);
+
+    static std::size_t constexpr size()
+    {
+        return sizeof...(Ints);
+    }
+};
+
+template<std::size_t... Ints>
+using index_sequence = integer_sequence<std::size_t, Ints...>;
+
+// This workaround is needed for broken sizeof...
+template<class... Args>
+struct sizeof_workaround
+{
+    static std::size_t constexpr size = sizeof... (Args);
+};
+
+#ifdef _MSC_VER
+
+// This implementation compiles on MSVC and clang but not gcc
+
+template<class T, unsigned long long N, class Seq>
+struct make_integer_sequence_unchecked;
+
+template<class T, unsigned long long N, unsigned long long ...Indices>
+struct make_integer_sequence_unchecked<
+    T, N, integer_sequence<T, Indices...>>
+{
+    using type = typename make_integer_sequence_unchecked<
+        T, N-1, integer_sequence<T, N-1, Indices...>>::type;
+};
+
+template<class T, unsigned long long ...Indices>
+struct make_integer_sequence_unchecked<
+    T, 0, integer_sequence<T, Indices...>>
+{
+    using type = integer_sequence<T, Indices...>;
+};
+
+template<class T, T N>
+struct make_integer_sequence_checked
+{
+    static_assert (std::is_integral<T>::value,
+        "T must be an integral type");
+
+    static_assert (N >= 0,
+        "N must be non-negative");
+
+    using type = typename make_integer_sequence_unchecked<
+        T, N, integer_sequence<T>>::type;
+};
+
+template<class T, T N>
+using make_integer_sequence =
+    typename make_integer_sequence_checked<T, N>::type;
+
+template<std::size_t N>
+using make_index_sequence = make_integer_sequence<std::size_t, N>;
+
+template<class... Args>
+using index_sequence_for =
+    make_index_sequence<sizeof_workaround<Args...>::size>;
+
+#else
+
+// This implementation compiles on gcc but not MSVC
+
+template<std::size_t... Ints>
+struct index_tuple
+{
+    using next = index_tuple<Ints..., sizeof... (Ints)>;
+
+};
+
+template<std::size_t N>
+struct build_index_tuple
+{
+    using type = typename build_index_tuple<N-1>::type::next;
+};
+
+template<>
+struct build_index_tuple<0>
+{
+    using type = index_tuple<>;
+};
+
+template<class T, T N,
+    class Seq = typename build_index_tuple<N>::type
+>
+struct integer_sequence_helper;
+
+template<class T, T N, std::size_t... Ints>
+struct integer_sequence_helper<T, N, index_tuple<Ints...>>
+{
+    static_assert (std::is_integral<T>::value,
+        "T must be an integral type");
+
+    static_assert (N >= 0,
+        "N must be non-negative");
+
+    using type = integer_sequence<T, static_cast<T> (Ints)...>;
+};
+
+template<class T, T N>
+using make_integer_sequence =
+    typename integer_sequence_helper<T, N>::type;
+
+template<std::size_t N>
+using make_index_sequence = make_integer_sequence<std::size_t, N>;
+
+template<class... Args>
+using index_sequence_for =
+    make_index_sequence<sizeof_workaround<Args...>::size>;
+
+#endif
+
+} // detail
+} // beast
+
+#endif