71 lines
2.1 KiB
C++
71 lines
2.1 KiB
C++
|
/*!
|
||
|
|
@file
|
||
|
|
Forward declares `boost::hana::not_equal`.
|
||
|
|
|
||
|
|
@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_NOT_EQUAL_HPP
|
||
|
|
#define BOOST_HANA_FWD_NOT_EQUAL_HPP
|
||
|
|
|
||
|
|
#include <boost/hana/config.hpp>
|
||
|
|
#include <boost/hana/core/when.hpp>
|
||
|
|
#include <boost/hana/detail/nested_to_fwd.hpp>
|
||
|
|
|
||
|
|
|
||
|
|
BOOST_HANA_NAMESPACE_BEGIN
|
||
|
|
//! Returns a `Logical` representing whether `x` is not equal to `y`.
|
||
|
|
//! @ingroup group-Comparable
|
||
|
|
//!
|
||
|
|
//! The `not_equal` function can be called in two different ways. First,
|
||
|
|
//! it can be called like a normal function:
|
||
|
|
//! @code
|
||
|
|
//! not_equal(x, y)
|
||
|
|
//! @endcode
|
||
|
|
//!
|
||
|
|
//! However, it may also be partially applied to an argument by using
|
||
|
|
//! `not_equal.to`:
|
||
|
|
//! @code
|
||
|
|
//! not_equal.to(x)(y) == not_equal(x, y)
|
||
|
|
//! @endcode
|
||
|
|
//!
|
||
|
|
//! In other words, `not_equal.to(x)` is a function object that is
|
||
|
|
//! equivalent to `partial(not_equal, x)`. This is provided to enhance
|
||
|
|
//! the readability of some constructs, especially when using higher
|
||
|
|
//! order algorithms.
|
||
|
|
//!
|
||
|
|
//!
|
||
|
|
//! Signature
|
||
|
|
//! ---------
|
||
|
|
//! Given a Logical `Bool` and two Comparables `A` and `B` that
|
||
|
|
//! share a common embedding, the signature is
|
||
|
|
//! @f$ \mathtt{not\_equal} : A \times B \to Bool @f$.
|
||
|
|
//!
|
||
|
|
//! @param x, y
|
||
|
|
//! Two objects to compare for inequality.
|
||
|
|
//!
|
||
|
|
//!
|
||
|
|
//! Example
|
||
|
|
//! -------
|
||
|
|
//! @include example/not_equal.cpp
|
||
|
|
#ifdef BOOST_HANA_DOXYGEN_INVOKED
|
||
|
|
constexpr auto not_equal = [](auto&& x, auto&& y) {
|
||
|
|
return tag-dispatched;
|
||
|
|
};
|
||
|
|
#else
|
||
|
|
template <typename T, typename U, typename = void>
|
||
|
|
struct not_equal_impl : not_equal_impl<T, U, when<true>> { };
|
||
|
|
|
||
|
|
struct not_equal_t : detail::nested_to<not_equal_t> {
|
||
|
|
template <typename X, typename Y>
|
||
|
|
constexpr auto operator()(X&& x, Y&& y) const;
|
||
|
|
};
|
||
|
|
|
||
|
|
constexpr not_equal_t not_equal{};
|
||
|
|
#endif
|
||
|
|
BOOST_HANA_NAMESPACE_END
|
||
|
|
|
||
|
|
#endif // !BOOST_HANA_FWD_NOT_EQUAL_HPP
|