power.hpp
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/*!
@file
Forward declares `boost::hana::power`.
Copyright Louis Dionne 2013-2022
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
*/
#ifndef BOOST_HANA_FWD_POWER_HPP
#define BOOST_HANA_FWD_POWER_HPP
#include <boost/hana/config.hpp>
#include <boost/hana/core/when.hpp>
namespace boost { namespace hana {
//! Elevate a ring element to its `n`th power.
//! @ingroup group-Ring
//!
//! Specifically, `power(x, n)`, is equivalent to multiplying `x` with
//! itself `n` times using the Ring's multiplication. If the power is
//! equal to `zero`, the Ring's identity (`one`) is returned.
//!
//! @param x
//! A `Ring` element that is elevated to its `n`th power.
//!
//! @param n
//! A non-negative `IntegralConstant` representing the power to which `x`
//! is elevated.
//!
//!
//! @note
//! Only the tag of `x` is used for tag-dispatching.
//!
//! Example
//! -------
//! @include example/power.cpp
#ifdef BOOST_HANA_DOXYGEN_INVOKED
constexpr auto power = [](auto&& x, auto const& n) -> decltype(auto) {
return tag-dispatched;
};
#else
template <typename R, typename = void>
struct power_impl : power_impl<R, when<true>> { };
struct power_t {
template <typename X, typename N>
constexpr decltype(auto) operator()(X&& x, N const& n) const;
};
BOOST_HANA_INLINE_VARIABLE constexpr power_t power{};
#endif
}} // end namespace boost::hana
#endif // !BOOST_HANA_FWD_POWER_HPP