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Telegram/ThirdParty/range-v3/include/range/v3/view/counted.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_VIEW_COUNTED_HPP
+#define RANGES_V3_VIEW_COUNTED_HPP
+
+#include <utility>
+
+#include <range/v3/range_fwd.hpp>
+
+#include <range/v3/iterator/concepts.hpp>
+#include <range/v3/iterator/counted_iterator.hpp>
+#include <range/v3/iterator/default_sentinel.hpp>
+#include <range/v3/iterator/traits.hpp>
+#include <range/v3/utility/static_const.hpp>
+#include <range/v3/view/interface.hpp>
+#include <range/v3/view/subrange.hpp>
+
+#include <range/v3/detail/prologue.hpp>
+
+namespace ranges
+{
+    /// \addtogroup group-views
+    /// @{
+    template<typename I>
+    struct counted_view : view_interface<counted_view<I>, finite>
+    {
+    private:
+        friend range_access;
+        I it_;
+        iter_difference_t<I> n_;
+
+    public:
+        counted_view() = default;
+        counted_view(I it, iter_difference_t<I> n)
+          : it_(it)
+          , n_(n)
+        {
+            RANGES_EXPECT(0 <= n_);
+        }
+        counted_iterator<I> begin() const
+        {
+            return make_counted_iterator(it_, n_);
+        }
+        default_sentinel_t end() const
+        {
+            return {};
+        }
+        auto size() const
+        {
+            return static_cast<detail::iter_size_t<I>>(n_);
+        }
+    };
+
+    template<typename I>
+    RANGES_INLINE_VAR constexpr bool enable_borrowed_range<counted_view<I>> = true;
+
+#if RANGES_CXX_DEDUCTION_GUIDES >= RANGES_CXX_DEDUCTION_GUIDES_17
+    template<typename I>
+    counted_view(I, iter_difference_t<I>)
+        -> counted_view<I>;
+#endif
+
+    namespace views
+    {
+        struct cpp20_counted_fn
+        {
+            template(typename I)(
+                requires input_or_output_iterator<I> AND (!random_access_iterator<I>)) //
+            subrange<counted_iterator<I>, default_sentinel_t> //
+            operator()(I it, iter_difference_t<I> n) const
+            {
+                return {make_counted_iterator(std::move(it), n), default_sentinel};
+            }
+            template(typename I)(
+                requires random_access_iterator<I>)
+            subrange<I> operator()(I it, iter_difference_t<I> n) const
+            {
+                return {it, it + n};
+            }
+        };
+
+        struct counted_fn
+        {
+            template(typename I)(
+                requires input_or_output_iterator<I> AND (!random_access_iterator<I>)) //
+            counted_view<I> operator()(I it, iter_difference_t<I> n) const
+            {
+                return {std::move(it), n};
+            }
+            template(typename I)(
+                requires random_access_iterator<I>)
+            subrange<I> operator()(I it, iter_difference_t<I> n) const
+            {
+                return {it, it + n};
+            }
+        };
+
+        /// \relates counted_fn
+        /// \ingroup group-views
+        RANGES_INLINE_VARIABLE(counted_fn, counted)
+    } // namespace views
+
+    namespace cpp20
+    {
+        namespace views
+        {
+            RANGES_INLINE_VARIABLE(ranges::views::cpp20_counted_fn, counted)
+        }
+    } // namespace cpp20
+    /// @}
+} // namespace ranges
+
+#include <range/v3/detail/epilogue.hpp>
+#include <range/v3/detail/satisfy_boost_range.hpp>
+RANGES_SATISFY_BOOST_RANGE(::ranges::counted_view)
+
+#endif