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Telegram/ThirdParty/range-v3/include/range/v3/functional/overload.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_FUNCTIONAL_OVERLOAD_HPP
+#define RANGES_V3_FUNCTIONAL_OVERLOAD_HPP
+
+#include <meta/meta.hpp>
+
+#include <concepts/concepts.hpp>
+
+#include <range/v3/range_fwd.hpp>
+
+#include <range/v3/functional/concepts.hpp>
+#include <range/v3/functional/invoke.hpp>
+#include <range/v3/utility/static_const.hpp>
+
+#include <range/v3/detail/prologue.hpp>
+
+namespace ranges
+{
+    /// \addtogroup group-functional
+    /// @{
+    /// \cond
+    namespace detail
+    {
+        struct _id
+        {
+            template<typename T>
+            using invoke = T;
+        };
+        struct _ref
+        {
+            template<typename T>
+            using invoke = T &;
+        };
+        struct _cref
+        {
+            template<typename T>
+            using invoke = T const &;
+        };
+        template<typename T>
+        struct _bind_front
+        {
+            template<typename... Args>
+            using invoke = invoke_result_t<T, Args...>;
+        };
+    } // namespace detail
+    /// \endcond
+
+    template<typename... Ts>
+    struct overloaded;
+
+    template<>
+    struct overloaded<>
+    {
+    private:
+        template<typename...>
+        friend struct overloaded;
+        template<typename, typename...>
+        using _result_t = void;
+    };
+
+    template<typename First, typename... Rest>
+    struct overloaded<First, Rest...>
+    {
+    private:
+        template<typename...>
+        friend struct overloaded;
+
+        RANGES_NO_UNIQUE_ADDRESS
+        First first_;
+        RANGES_NO_UNIQUE_ADDRESS
+        overloaded<Rest...> second_;
+
+        template<typename Qual>
+        using _result_first = detail::_bind_front<meta::invoke<Qual, First>>;
+        template<typename Qual>
+        struct _result_second
+        {
+            template<typename... Args>
+            using invoke = typename overloaded<Rest...>
+                ::template _result_t<Qual, Args...>;
+        };
+
+        template<typename Qual, typename... Args>
+        using _result_t =
+            meta::invoke<
+                meta::conditional_t<
+                    (bool) invocable<meta::invoke<Qual, First>, Args...>,
+                    _result_first<Qual>,
+                    _result_second<Qual>>,
+                Args...>;
+
+    public:
+        overloaded() = default;
+        constexpr overloaded(First first, Rest... rest)
+          : first_(static_cast<First &&>(first))
+          , second_{static_cast<Rest &&>(rest)...}
+        {}
+
+        template(typename... Args)(
+            requires invocable<First, Args...>)
+        constexpr _result_t<detail::_id, Args...> operator()(Args &&... args) &&
+        {
+            return invoke((First &&) first_, (Args &&) args...);
+        }
+        template(typename... Args)(
+            requires (!invocable<First, Args...>) AND
+                invocable<overloaded<Rest...>, Args...>)
+        constexpr _result_t<detail::_id, Args...> operator()(Args &&... args) &&
+        {
+            return invoke((overloaded<Rest...> &&) second_, (Args &&) args...);
+        }
+
+        template(typename... Args)(
+            requires invocable<First &, Args...>)
+        constexpr _result_t<detail::_ref, Args...> operator()(Args &&... args) &
+        {
+            return invoke(first_, (Args &&) args...);
+        }
+        template(typename... Args)(
+            requires (!invocable<First &, Args...>) AND
+                invocable<overloaded<Rest...> &, Args...>)
+        constexpr _result_t<detail::_ref, Args...> operator()(Args &&... args) &
+        {
+            return invoke(second_, (Args &&) args...);
+        }
+
+        template(typename... Args)(
+            requires invocable<First const &, Args...>)
+        constexpr _result_t<detail::_cref, Args...> operator()(Args &&... args) const &
+        {
+            return invoke(first_, (Args &&) args...);
+        }
+        template(typename... Args)(
+            requires (!invocable<First const &, Args...>) AND
+                invocable<overloaded<Rest...> const &, Args...>)
+        constexpr _result_t<detail::_cref, Args...> operator()(Args &&... args) const &
+        {
+            return invoke(second_, (Args &&) args...);
+        }
+    };
+
+    struct overload_fn
+    {
+        template<typename Fn>
+        constexpr Fn operator()(Fn fn) const
+        {
+            return fn;
+        }
+        template<typename... Fns>
+        constexpr overloaded<Fns...> operator()(Fns... fns) const
+        {
+            return overloaded<Fns...>{static_cast<Fns &&>(fns)...};
+        }
+    };
+
+    /// \ingroup group-functional
+    /// \sa `overload_fn`
+    RANGES_INLINE_VARIABLE(overload_fn, overload)
+    /// @}
+} // namespace ranges
+
+#include <range/v3/detail/epilogue.hpp>
+
+#endif