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Telegram/ThirdParty/range-v3/include/range/v3/view/linear_distribute.hpp

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+/// \file
+// Range v3 library
+//
+//  Copyright Casey Carter 2017
+//  Copyright Gonzalo Brito Gadeschi 2017
+//
+//  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_LINEAR_DISTRIBUTE_HPP
+#define RANGES_V3_VIEW_LINEAR_DISTRIBUTE_HPP
+
+#include <type_traits>
+
+#include <meta/meta.hpp>
+
+#include <range/v3/range_fwd.hpp>
+
+#include <range/v3/iterator/default_sentinel.hpp>
+#include <range/v3/utility/static_const.hpp>
+#include <range/v3/view/facade.hpp>
+
+#include <range/v3/detail/prologue.hpp>
+
+namespace ranges
+{
+    namespace views
+    {
+        /// \addtogroup group-views
+        /// @{
+
+        template<typename T>
+        struct linear_distribute_view : view_facade<linear_distribute_view<T>, finite>
+        {
+            CPP_assert(std::is_arithmetic<T>());
+
+        private:
+            friend range_access;
+            using Calc = meta::conditional_t<std::is_floating_point<T>::value, T, double>;
+
+            T from_, to_;
+            Calc delta_;
+            std::ptrdiff_t n_;
+
+            constexpr T read() const noexcept
+            {
+                return from_;
+            }
+            constexpr bool equal(default_sentinel_t) const noexcept
+            {
+                return n_ == 0;
+            }
+            constexpr bool equal(linear_distribute_view const & other) const noexcept
+            {
+                bool const eq = n_ == other.n_;
+                RANGES_DIAGNOSTIC_PUSH
+                RANGES_DIAGNOSTIC_IGNORE_FLOAT_EQUAL
+                RANGES_EXPECT(to_ == other.to_);
+                RANGES_EXPECT(!eq || from_ == other.from_);
+                RANGES_DIAGNOSTIC_POP
+                return eq;
+            }
+            constexpr void next() noexcept
+            {
+                RANGES_EXPECT(n_ > 0);
+                --n_;
+                if(n_ == 0)
+                {
+                    from_ = to_;
+                }
+                else
+                {
+                    from_ = T(to_ - (delta_ * Calc(n_ - 1)));
+                }
+            }
+
+        public:
+            constexpr linear_distribute_view() = default;
+            constexpr linear_distribute_view(T from, T to, std::ptrdiff_t n) noexcept
+              : from_(from)
+              , to_(to)
+              , delta_(n > 1 ? (to - from) / Calc(n - 1) : 0)
+              , n_(n)
+            {
+                RANGES_EXPECT(n_ > 0);
+                RANGES_EXPECT(to_ >= from_);
+            }
+            constexpr std::size_t size() const noexcept
+            {
+                return static_cast<std::size_t>(n_);
+            }
+        };
+
+        /// Distributes `n` values linearly in the closed interval [`from`, `to`].
+        ///
+        /// \pre `from <= to && n > 0`
+        ///
+        /// If `from == to`, returns n-times `to`.
+        /// If `n == 1` returns `to`.
+        struct linear_distribute_fn
+        {
+            template(typename T)(
+                requires std::is_arithmetic<T>::value)
+            constexpr auto operator()(T from, T to, std::ptrdiff_t n) const
+            {
+                return linear_distribute_view<T>{from, to, n};
+            }
+        };
+
+        /// \relates linear_distribute_fn
+        /// \ingroup group-views
+        RANGES_INLINE_VARIABLE(linear_distribute_fn, linear_distribute)
+    } // namespace views
+} // namespace ranges
+
+#include <range/v3/detail/epilogue.hpp>
+
+#endif