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| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | /*! |
| 2 | @file | |
| 3 | Forward declares `boost::hana::power`. | |
| 4 | ||
| 5 | @copyright Louis Dionne 2013-2016 | |
| 6 | Distributed under the Boost Software License, Version 1.0. | |
| 7 | (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) | |
| 8 | */ | |
| 9 | ||
| 10 | #ifndef BOOST_HANA_FWD_POWER_HPP | |
| 11 | #define BOOST_HANA_FWD_POWER_HPP | |
| 12 | ||
| 13 | #include <boost/hana/config.hpp> | |
| 14 | #include <boost/hana/core/when.hpp> | |
| 15 | ||
| 16 | ||
| 17 | BOOST_HANA_NAMESPACE_BEGIN | |
| 18 | //! Elevate a ring element to its `n`th power. | |
| 19 | //! @ingroup group-Ring | |
| 20 | //! | |
| 21 | //! Specifically, `power(x, n)`, is equivalent to multiplying `x` with | |
| 22 | //! itself `n` times using the Ring's multiplication. If the power is | |
| 23 | //! equal to `zero`, the Ring's identity (`one`) is returned. | |
| 24 | //! | |
| 25 | //! @param x | |
| 26 | //! A `Ring` element that is elevated to its `n`th power. | |
| 27 | //! | |
| 28 | //! @param n | |
| 29 | //! A non-negative `IntegralConstant` representing the power to which `x` | |
| 30 | //! is elevated. | |
| 31 | //! | |
| 32 | //! | |
| 33 | //! @note | |
| 34 | //! Only the tag of `x` is used for tag-dispatching. | |
| 35 | //! | |
| 36 | //! Example | |
| 37 | //! ------- | |
| 38 | //! @include example/power.cpp | |
| 39 | #ifdef BOOST_HANA_DOXYGEN_INVOKED | |
| 40 | constexpr auto power = [](auto&& x, auto const& n) -> decltype(auto) { | |
| 41 | return tag-dispatched; | |
| 42 | }; | |
| 43 | #else | |
| 44 | template <typename R, typename = void> | |
| 45 | struct power_impl : power_impl<R, when<true>> { }; | |
| 46 | ||
| 47 | struct power_t { | |
| 48 | template <typename X, typename N> | |
| 49 | constexpr decltype(auto) operator()(X&& x, N const& n) const; | |
| 50 | }; | |
| 51 | ||
| 52 | constexpr power_t power{}; | |
| 53 | #endif | |
| 54 | BOOST_HANA_NAMESPACE_END | |
| 55 | ||
| 56 | #endif // !BOOST_HANA_FWD_POWER_HPP |