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Telegram/ThirdParty/range-v3/include/range/v3/view/tail.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_TAIL_HPP
+#define RANGES_V3_VIEW_TAIL_HPP
+
+#include <type_traits>
+#include <utility>
+
+#include <range/v3/range_fwd.hpp>
+
+#include <range/v3/iterator/operations.hpp>
+#include <range/v3/range/access.hpp>
+#include <range/v3/range/concepts.hpp>
+#include <range/v3/range/primitives.hpp>
+#include <range/v3/range/traits.hpp>
+#include <range/v3/utility/static_const.hpp>
+#include <range/v3/view/all.hpp>
+#include <range/v3/view/interface.hpp>
+#include <range/v3/view/view.hpp>
+
+#include <range/v3/detail/prologue.hpp>
+
+namespace ranges
+{
+    namespace detail
+    {
+        template<typename T>
+        constexpr T prev_or_zero_(T n)
+        {
+            return n == 0 ? T(0) : T(n - 1);
+        }
+    } // namespace detail
+
+    /// \addtogroup group-views
+    /// @{
+    template<typename Rng>
+    struct tail_view
+      : view_interface<tail_view<Rng>,
+                       (range_cardinality<Rng>::value >= 0)
+                           ? detail::prev_or_zero_(range_cardinality<Rng>::value)
+                           : range_cardinality<Rng>::value>
+    {
+    private:
+        Rng rng_;
+
+    public:
+        tail_view() = default;
+        tail_view(Rng rng)
+          : rng_(static_cast<Rng &&>(rng))
+        {
+            CPP_assert(input_range<Rng>);
+        }
+        iterator_t<Rng> begin()
+        {
+            return next(ranges::begin(rng_), 1, ranges::end(rng_));
+        }
+        template(bool Const = true)(
+            requires Const AND range<meta::const_if_c<Const, Rng>>)
+        iterator_t<meta::const_if_c<Const, Rng>> begin() const
+        {
+            return next(ranges::begin(rng_), 1, ranges::end(rng_));
+        }
+        sentinel_t<Rng> end()
+        {
+            return ranges::end(rng_);
+        }
+        template(bool Const = true)(
+            requires Const AND range<meta::const_if_c<Const, Rng>>)
+        sentinel_t<meta::const_if_c<Const, Rng>> end() const
+        {
+            return ranges::end(rng_);
+        }
+        // Strange cast to bool in the requires clause is to work around gcc bug.
+        CPP_auto_member
+        constexpr auto CPP_fun(size)()(
+            requires(bool(sized_range<Rng>)))
+        {
+            using size_type = range_size_t<Rng>;
+            return range_cardinality<Rng>::value >= 0
+                       ? detail::prev_or_zero_((size_type)range_cardinality<Rng>::value)
+                       : detail::prev_or_zero_(ranges::size(rng_));
+        }
+        CPP_auto_member
+        constexpr auto CPP_fun(size)()(const //
+            requires(bool(sized_range<Rng const>)))
+        {
+            using size_type = range_size_t<Rng>;
+            return range_cardinality<Rng>::value >= 0
+                       ? detail::prev_or_zero_((size_type)range_cardinality<Rng>::value)
+                       : detail::prev_or_zero_(ranges::size(rng_));
+        }
+        Rng base() const
+        {
+            return rng_;
+        }
+    };
+
+    template<typename Rng>
+    RANGES_INLINE_VAR constexpr bool enable_borrowed_range<tail_view<Rng>> = //
+        enable_borrowed_range<Rng>;
+
+#if RANGES_CXX_DEDUCTION_GUIDES >= RANGES_CXX_DEDUCTION_GUIDES_17
+    template(typename Rng)(
+        requires viewable_range<Rng>)
+        tail_view(Rng &&)
+            ->tail_view<views::all_t<Rng>>;
+#endif
+
+    namespace views
+    {
+        struct tail_fn
+        {
+            template(typename Rng)(
+                requires viewable_range<Rng> AND input_range<Rng>)
+            meta::if_c<range_cardinality<Rng>::value == 0,
+                       all_t<Rng>,
+                       tail_view<all_t<Rng>>> //
+            operator()(Rng && rng) const
+            {
+                return all(static_cast<Rng &&>(rng));
+            }
+        };
+
+        /// \relates tail_fn
+        /// \ingroup group-views
+        RANGES_INLINE_VARIABLE(view_closure<tail_fn>, tail)
+    } // namespace views
+    /// @}
+} // namespace ranges
+
+#include <range/v3/detail/epilogue.hpp>
+#include <range/v3/detail/satisfy_boost_range.hpp>
+RANGES_SATISFY_BOOST_RANGE(::ranges::tail_view)
+
+#endif