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Telegram/ThirdParty/range-v3/include/range/v3/action/stride.hpp

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+/// \file
+// Range v3 library
+//
+//  Copyright Eric Niebler 2013-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_ACTION_STRIDE_HPP
+#define RANGES_V3_ACTION_STRIDE_HPP
+
+#include <range/v3/range_fwd.hpp>
+
+#include <range/v3/action/action.hpp>
+#include <range/v3/action/erase.hpp>
+#include <range/v3/functional/bind_back.hpp>
+#include <range/v3/iterator/concepts.hpp>
+#include <range/v3/iterator/operations.hpp>
+#include <range/v3/iterator/traits.hpp>
+#include <range/v3/utility/static_const.hpp>
+
+#include <range/v3/detail/prologue.hpp>
+
+namespace ranges
+{
+    /// \addtogroup group-actions
+    /// @{
+    namespace actions
+    {
+        struct stride_fn
+        {
+            template(typename D)(
+                requires detail::integer_like_<D>)
+            constexpr auto operator()(D step) const
+            {
+                return make_action_closure(bind_back(stride_fn{}, step));
+            }
+
+            template(typename Rng, typename D = range_difference_t<Rng>)(
+                requires forward_range<Rng> AND
+                    erasable_range<Rng &, iterator_t<Rng>, sentinel_t<Rng>> AND
+                    permutable<iterator_t<Rng>>)
+            Rng operator()(Rng && rng, range_difference_t<Rng> const step) const
+            {
+                using I = iterator_t<Rng>;
+                using S = sentinel_t<Rng>;
+                RANGES_EXPECT(0 < step);
+                if(1 < step)
+                {
+                    I first = ranges::begin(rng);
+                    S const last = ranges::end(rng);
+                    if(first != last)
+                    {
+                        for(I i = ranges::next(++first, step - 1, last); i != last;
+                            advance(i, step, last), ++first)
+                        {
+                            *first = iter_move(i);
+                        }
+                    }
+                    ranges::actions::erase(rng, first, last);
+                }
+                return static_cast<Rng &&>(rng);
+            }
+        };
+
+        /// \relates actions::stride_fn
+        RANGES_INLINE_VARIABLE(stride_fn, stride)
+    } // namespace actions
+    /// @}
+} // namespace ranges
+
+#include <range/v3/detail/epilogue.hpp>
+
+#endif