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174 lines
4.3 KiB
C++
174 lines
4.3 KiB
C++
//------------------------------------------------------------------------------
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/*
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This file is part of Beast: https://github.com/vinniefalco/Beast
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Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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//==============================================================================
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#ifndef BEAST_CXX14_UTILITY_H_INCLUDED
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#define BEAST_CXX14_UTILITY_H_INCLUDED
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#include <beast/cxx14/config.h>
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#include <cstddef>
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#include <type_traits>
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#include <utility>
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#if ! BEAST_NO_CXX14_INTEGER_SEQUENCE
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namespace std {
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template <class T, T... Ints>
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struct integer_sequence
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{
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using value_type = T;
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static_assert (is_integral<T>::value,
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"std::integer_sequence can only be instantiated with an integral type" );
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static const size_t static_size = sizeof...(Ints);
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static /* constexpr */ size_t size() /* noexcept */
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{
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return sizeof...(Ints);
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}
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};
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template <size_t... Ints>
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using index_sequence = integer_sequence <size_t, Ints...>;
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namespace detail {
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// This workaround is needed for msvc broken sizeof...
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template <class... Args>
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struct sizeof_workaround
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{
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static size_t const size = sizeof... (Args);
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};
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} // detail
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#ifdef _MSC_VER
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// This implementation compiles on MSVC and clang but not gcc
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namespace detail {
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template <class T, unsigned long long N, class Seq>
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struct make_integer_sequence_unchecked;
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template <class T, unsigned long long N, unsigned long long ...Indices>
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struct make_integer_sequence_unchecked <
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T, N, integer_sequence <T, Indices...>>
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{
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using type = typename make_integer_sequence_unchecked<
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T, N-1, integer_sequence<T, N-1, Indices...>>::type;
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};
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template <class T, unsigned long long ...Indices>
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struct make_integer_sequence_unchecked <
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T, 0, integer_sequence<T, Indices...>>
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{
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using type = integer_sequence <T, Indices...>;
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};
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template <class T, T N>
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struct make_integer_sequence_checked
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{
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static_assert (is_integral <T>::value,
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"T must be an integral type");
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static_assert (N >= 0,
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"N must be non-negative");
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using type = typename make_integer_sequence_unchecked <
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T, N, integer_sequence<T>>::type;
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};
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} // detail
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template <class T, T N>
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using make_integer_sequence =
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typename detail::make_integer_sequence_checked <T, N>::type;
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template <size_t N>
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using make_index_sequence = make_integer_sequence <size_t, N>;
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template <class... Args>
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using index_sequence_for =
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make_index_sequence <detail::sizeof_workaround <Args...>::size>;
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#else
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// This implementation compiles on gcc but not MSVC
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namespace detail {
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template <size_t... Ints>
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struct index_tuple
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{
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using next = index_tuple <Ints..., sizeof... (Ints)>;
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};
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template <size_t N>
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struct build_index_tuple
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{
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using type = typename build_index_tuple <N-1>::type::next;
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};
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template <>
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struct build_index_tuple <0>
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{
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using type = index_tuple<>;
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};
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template <class T, T N,
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class Seq = typename build_index_tuple <N>::type
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>
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struct make_integer_sequence;
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template <class T, T N, size_t... Ints>
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struct make_integer_sequence <T, N, index_tuple <Ints...>>
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{
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static_assert (is_integral <T>::value,
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"T must be an integral type");
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static_assert (N >= 0,
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"N must be non-negative");
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using type = integer_sequence <T, static_cast <T> (Ints)...>;
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};
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} // detail
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template <class T, T N>
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using make_integer_sequence =
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typename detail::make_integer_sequence <T, N>::type;
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template <size_t N>
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using make_index_sequence = make_integer_sequence <size_t, N>;
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template <class... Args>
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using index_sequence_for =
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make_index_sequence <detail::sizeof_workaround <Args...>::size>;
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#endif
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}
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#endif
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#endif
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