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2020-10-17 20:11:16 -04:00

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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_CONCEPTS_HPP
#define RANGES_V3_FUNCTIONAL_CONCEPTS_HPP
#include <concepts/concepts.hpp>
#include <range/v3/functional/invoke.hpp>
#include <range/v3/detail/prologue.hpp>
namespace ranges
{
/// \addtogroup group-functional
/// @{
// clang-format off
// WORKAROUND mysterious msvc bug
#if defined(_MSC_VER)
template<typename Fun, typename... Args>
CPP_concept invocable =
std::is_invocable_v<Fun, Args...>;
#else
template<typename Fun, typename... Args>
CPP_requires(invocable_,
requires(Fun && fn) //
(
invoke((Fun &&) fn, std::declval<Args>()...)
));
template<typename Fun, typename... Args>
CPP_concept invocable =
CPP_requires_ref(ranges::invocable_, Fun, Args...);
#endif
template<typename Fun, typename... Args>
CPP_concept regular_invocable =
invocable<Fun, Args...>;
// Axiom: equality_preserving(invoke(f, args...))
template<typename Fun, typename... Args>
CPP_requires(predicate_,
requires(Fun && fn) //
(
concepts::requires_<
convertible_to<
decltype(invoke((Fun &&) fn, std::declval<Args>()...)),
bool>>
));
template<typename Fun, typename... Args>
CPP_concept predicate =
regular_invocable<Fun, Args...> &&
CPP_requires_ref(ranges::predicate_, Fun, Args...);
template<typename R, typename T, typename U>
CPP_concept relation =
predicate<R, T, T> &&
predicate<R, U, U> &&
predicate<R, T, U> &&
predicate<R, U, T>;
template<typename R, typename T, typename U>
CPP_concept strict_weak_order =
relation<R, T, U>;
// clang-format on
namespace cpp20
{
using ranges::invocable;
using ranges::predicate;
using ranges::regular_invocable;
using ranges::relation;
using ranges::strict_weak_order;
} // namespace cpp20
/// @}
} // namespace ranges
#include <range/v3/detail/epilogue.hpp>
#endif