43 lines
994 B
C++
43 lines
994 B
C++
#pragma once
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#include <cstddef>
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#include "dxxsconf.h"
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#ifdef DXX_HAVE_CXX14_INTEGER_SEQUENCE
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#include <utility>
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using std::index_sequence;
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#else
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template <std::size_t...>
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struct index_sequence {};
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#endif
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template <std::size_t, typename, std::size_t, typename>
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struct cat_index_sequence;
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template <std::size_t... N1, std::size_t A2, std::size_t... N2>
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struct cat_index_sequence<0, index_sequence<N1...>, A2, index_sequence<N2...>>
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{
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typedef index_sequence<N1..., A2 + N2...> type;
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};
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/* Fan out to reduce template depth */
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template <std::size_t N>
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struct tree_index_sequence
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{
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typedef typename cat_index_sequence<0, typename tree_index_sequence<N / 2>::type, N / 2, typename tree_index_sequence<(N + 1) / 2>::type>::type type;
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};
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template <>
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struct tree_index_sequence<0>
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{
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typedef index_sequence<> type;
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};
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template <>
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struct tree_index_sequence<1>
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{
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typedef index_sequence<0> type;
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};
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template <std::size_t N>
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using make_tree_index_sequence = typename tree_index_sequence<N>::type;
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