Revert "externals: Update boost to 1.72 and add Boost Context"

boost/mp11/integer_sequence.hpp

@@ -0,0 +1,112 @@
+#ifndef BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED
+#define BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED
+
+// Copyright 2015, 2017, 2019 Peter Dimov.
+//
+// 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
+
+#include <boost/mp11/version.hpp>
+#include <cstddef>
+
+#if defined(__has_builtin)
+# if __has_builtin(__make_integer_seq)
+#  define BOOST_MP11_HAS_MAKE_INTEGER_SEQ
+# endif
+#endif
+
+namespace boost
+{
+namespace mp11
+{
+
+// integer_sequence
+template<class T, T... I> struct integer_sequence
+{
+};
+
+#if defined(BOOST_MP11_HAS_MAKE_INTEGER_SEQ)
+
+template<class T, T N> using make_integer_sequence = __make_integer_seq<integer_sequence, T, N>;
+
+#else
+
+// detail::make_integer_sequence_impl
+namespace detail
+{
+
+// iseq_if_c
+template<bool C, class T, class E> struct iseq_if_c_impl;
+
+template<class T, class E> struct iseq_if_c_impl<true, T, E>
+{
+    using type = T;
+};
+
+template<class T, class E> struct iseq_if_c_impl<false, T, E>
+{
+    using type = E;
+};
+
+template<bool C, class T, class E> using iseq_if_c = typename iseq_if_c_impl<C, T, E>::type;
+
+// iseq_identity
+template<class T> struct iseq_identity
+{
+    using type = T;
+};
+
+template<class S1, class S2> struct append_integer_sequence;
+
+template<class T, T... I, T... J> struct append_integer_sequence<integer_sequence<T, I...>, integer_sequence<T, J...>>
+{
+    using type = integer_sequence< T, I..., ( J + sizeof...(I) )... >;
+};
+
+template<class T, T N> struct make_integer_sequence_impl;
+
+template<class T, T N> struct make_integer_sequence_impl_
+{
+private:
+
+    static_assert( N >= 0, "make_integer_sequence<T, N>: N must not be negative" );
+
+    static T const M = N / 2;
+    static T const R = N % 2;
+
+    using S1 = typename make_integer_sequence_impl<T, M>::type;
+    using S2 = typename append_integer_sequence<S1, S1>::type;
+    using S3 = typename make_integer_sequence_impl<T, R>::type;
+    using S4 = typename append_integer_sequence<S2, S3>::type;
+
+public:
+
+    using type = S4;
+};
+
+template<class T, T N> struct make_integer_sequence_impl: iseq_if_c<N == 0, iseq_identity<integer_sequence<T>>, iseq_if_c<N == 1, iseq_identity<integer_sequence<T, 0>>, make_integer_sequence_impl_<T, N> > >
+{
+};
+
+} // namespace detail
+
+// make_integer_sequence
+template<class T, T N> using make_integer_sequence = typename detail::make_integer_sequence_impl<T, N>::type;
+
+#endif // defined(BOOST_MP11_HAS_MAKE_INTEGER_SEQ)
+
+// index_sequence
+template<std::size_t... I> using index_sequence = integer_sequence<std::size_t, I...>;
+
+// make_index_sequence
+template<std::size_t N> using make_index_sequence = make_integer_sequence<std::size_t, N>;
+
+// index_sequence_for
+template<class... T> using index_sequence_for = make_integer_sequence<std::size_t, sizeof...(T)>;
+
+} // namespace mp11
+} // namespace boost
+
+#endif // #ifndef BOOST_MP11_INTEGER_SEQUENCE_HPP_INCLUDED