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Telegram/ThirdParty/range-v3/include/range/v3/algorithm/shuffle.hpp

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+/// \file
+// Range v3 library
+//
+//  Copyright Eric Niebler 2014-present
+//
+//  Use, modification and distribution is subject to 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)
+//
+// Project home: https://github.com/ericniebler/range-v3
+//
+#ifndef RANGES_V3_ALGORITHM_SHUFFLE_HPP
+#define RANGES_V3_ALGORITHM_SHUFFLE_HPP
+
+#include <cstdint>
+#include <utility>
+
+#include <range/v3/range_fwd.hpp>
+
+#include <range/v3/functional/invoke.hpp>
+#include <range/v3/iterator/concepts.hpp>
+#include <range/v3/iterator/traits.hpp>
+#include <range/v3/range/access.hpp>
+#include <range/v3/range/concepts.hpp>
+#include <range/v3/range/dangling.hpp>
+#include <range/v3/range/traits.hpp>
+#include <range/v3/utility/random.hpp>
+#include <range/v3/utility/static_const.hpp>
+#include <range/v3/utility/swap.hpp>
+
+#include <range/v3/detail/prologue.hpp>
+
+namespace ranges
+{
+    /// \addtogroup group-algorithms
+    /// @{
+    RANGES_FUNC_BEGIN(shuffle)
+
+        /// \brief function template \c shuffle
+        template(typename I, typename S, typename Gen = detail::default_random_engine &)(
+            requires random_access_iterator<I> AND sentinel_for<S, I> AND
+                permutable<I> AND
+                uniform_random_bit_generator<std::remove_reference_t<Gen>> AND
+                convertible_to<invoke_result_t<Gen &>, iter_difference_t<I>>)
+        I RANGES_FUNC(shuffle)(I const first,
+                               S const last,
+                               Gen && gen = detail::get_random_engine()) //
+        {
+            auto mid = first;
+            if(mid == last)
+                return mid;
+            using D1 = iter_difference_t<I>;
+            using D2 =
+                meta::conditional_t<std::is_integral<D1>::value, D1, std::ptrdiff_t>;
+            std::uniform_int_distribution<D2> uid{};
+            using param_t = typename decltype(uid)::param_type;
+            while(++mid != last)
+            {
+                RANGES_ENSURE(mid - first <= PTRDIFF_MAX);
+                if(auto const i = uid(gen, param_t{0, D2(mid - first)}))
+                    ranges::iter_swap(mid - i, mid);
+            }
+            return mid;
+        }
+
+        /// \overload
+        template(typename Rng, typename Gen = detail::default_random_engine &)(
+            requires random_access_range<Rng> AND permutable<iterator_t<Rng>> AND
+                uniform_random_bit_generator<std::remove_reference_t<Gen>> AND
+                convertible_to<invoke_result_t<Gen &>,
+                               iter_difference_t<iterator_t<Rng>>>)
+        borrowed_iterator_t<Rng> //
+        RANGES_FUNC(shuffle)(Rng && rng, Gen && rand = detail::get_random_engine()) //
+        {
+            return (*this)(begin(rng), end(rng), static_cast<Gen &&>(rand));
+        }
+
+    RANGES_FUNC_END(shuffle)
+
+    namespace cpp20
+    {
+        using ranges::shuffle;
+    }
+    /// @}
+} // namespace ranges
+
+#include <range/v3/detail/epilogue.hpp>
+
+#endif