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Telegram/ThirdParty/range-v3/include/range/v3/view/istream.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_VIEW_ISTREAM_HPP
+#define RANGES_V3_VIEW_ISTREAM_HPP
+
+#include <istream>
+
+#include <range/v3/range_fwd.hpp>
+
+#include <range/v3/iterator/default_sentinel.hpp>
+#include <range/v3/utility/semiregular_box.hpp>
+#include <range/v3/utility/static_const.hpp>
+#include <range/v3/view/facade.hpp>
+
+#include <range/v3/detail/prologue.hpp>
+
+namespace ranges
+{
+    /// \addtogroup group-views
+    /// @{
+    template<typename Val>
+    struct istream_view : view_facade<istream_view<Val>, unknown>
+    {
+    private:
+        friend range_access;
+        std::istream * sin_;
+        semiregular_box_t<Val> obj_;
+        struct cursor
+        {
+        private:
+            friend range_access;
+            using single_pass = std::true_type;
+            istream_view * rng_ = nullptr;
+
+        public:
+            cursor() = default;
+            explicit cursor(istream_view * rng)
+              : rng_(rng)
+            {}
+            void next()
+            {
+                rng_->next();
+            }
+            Val & read() const noexcept
+            {
+                return rng_->cached();
+            }
+            bool equal(default_sentinel_t) const
+            {
+                return !rng_->sin_;
+            }
+            bool equal(cursor that) const
+            {
+                return !rng_->sin_ == !that.rng_->sin_;
+            }
+        };
+        void next()
+        {
+            if(!(*sin_ >> cached()))
+                sin_ = nullptr;
+        }
+        cursor begin_cursor()
+        {
+            return cursor{this};
+        }
+
+    public:
+        istream_view() = default;
+        explicit istream_view(std::istream & sin)
+          : sin_(&sin)
+          , obj_{}
+        {
+            next(); // prime the pump
+        }
+        Val & cached() noexcept
+        {
+            return obj_;
+        }
+    };
+
+    /// \cond
+    template<typename Val>
+    using istream_range RANGES_DEPRECATED(
+        "istream_range<T> has been renamed to istream_view<T>") = istream_view<Val>;
+    /// \endcond
+
+    /// \cond
+    namespace _istream_
+    {
+        /// \endcond
+        template(typename Val)(
+            requires copy_constructible<Val> AND default_constructible<Val>)
+        inline istream_view<Val> istream(std::istream & sin)
+        {
+            return istream_view<Val>{sin};
+        }
+        /// \cond
+    } // namespace _istream_
+    using namespace _istream_;
+    /// \endcond
+
+    namespace cpp20
+    {
+        template<typename Val>
+        using basic_istream_view = ::ranges::istream_view<Val>;
+    } // namespace cpp20
+    /// @}
+} // namespace ranges
+
+#include <range/v3/detail/epilogue.hpp>
+
+#endif