| 123456789101112131415161718192021222324252627282930313233343536373839404142434445 |
- /*!
- @file
- Forward declares `boost::hana::one`.
- @copyright Louis Dionne 2013-2016
- 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_ONE_HPP
- #define BOOST_HANA_FWD_ONE_HPP
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/when.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! Identity of the `Ring` multiplication.
- //! @ingroup group-Ring
- //!
- //! @tparam R
- //! The tag (must be a model of `Ring`) of the returned identity.
- //!
- //!
- //! Example
- //! -------
- //! @include example/one.cpp
- #ifdef BOOST_HANA_DOXYGEN_INVOKED
- template <typename R>
- constexpr auto one = []() -> decltype(auto) {
- return tag-dispatched;
- };
- #else
- template <typename R, typename = void>
- struct one_impl : one_impl<R, when<true>> { };
- template <typename R>
- struct one_t;
- template <typename R>
- constexpr one_t<R> one{};
- #endif
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_FWD_ONE_HPP
|
