74 lines
2.4 KiB
C++
74 lines
2.4 KiB
C++
|
/*!
|
||
|
|
@file
|
||
|
|
Forward declares `boost::hana::contains` and `boost::hana::in`.
|
||
|
|
|
||
|
|
@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_CONTAINS_HPP
|
||
|
|
#define BOOST_HANA_FWD_CONTAINS_HPP
|
||
|
|
|
||
|
|
#include <boost/hana/config.hpp>
|
||
|
|
#include <boost/hana/core/when.hpp>
|
||
|
|
#include <boost/hana/functional/flip.hpp>
|
||
|
|
#include <boost/hana/functional/infix.hpp>
|
||
|
|
|
||
|
|
|
||
|
|
BOOST_HANA_NAMESPACE_BEGIN
|
||
|
|
//! Returns whether the key occurs in the structure.
|
||
|
|
//! @ingroup group-Searchable
|
||
|
|
//!
|
||
|
|
//! Given a `Searchable` structure `xs` and a `key`, `contains` returns
|
||
|
|
//! whether any of the keys of the structure is equal to the given `key`.
|
||
|
|
//! If the structure is not finite, an equal key has to appear at a finite
|
||
|
|
//! position in the structure for this method to finish. For convenience,
|
||
|
|
//! `contains` can also be applied in infix notation.
|
||
|
|
//!
|
||
|
|
//!
|
||
|
|
//! @param xs
|
||
|
|
//! The structure to search.
|
||
|
|
//!
|
||
|
|
//! @param key
|
||
|
|
//! A key to be searched for in the structure. The key has to be
|
||
|
|
//! `Comparable` with the other keys of the structure.
|
||
|
|
//!
|
||
|
|
//!
|
||
|
|
//! Example
|
||
|
|
//! -------
|
||
|
|
//! @include example/contains.cpp
|
||
|
|
#ifdef BOOST_HANA_DOXYGEN_INVOKED
|
||
|
|
constexpr auto contains = [](auto&& xs, auto&& key) {
|
||
|
|
return tag-dispatched;
|
||
|
|
};
|
||
|
|
#else
|
||
|
|
template <typename S, typename = void>
|
||
|
|
struct contains_impl : contains_impl<S, when<true>> { };
|
||
|
|
|
||
|
|
struct contains_t {
|
||
|
|
template <typename Xs, typename Key>
|
||
|
|
constexpr auto operator()(Xs&& xs, Key&& key) const;
|
||
|
|
};
|
||
|
|
|
||
|
|
constexpr auto contains = hana::infix(contains_t{});
|
||
|
|
#endif
|
||
|
|
|
||
|
|
//! Return whether the key occurs in the structure.
|
||
|
|
//! @ingroup group-Searchable
|
||
|
|
//!
|
||
|
|
//! Specifically, this is equivalent to `contains`, except `in` takes its
|
||
|
|
//! arguments in reverse order. Like `contains`, `in` can also be applied
|
||
|
|
//! in infix notation for increased expressiveness. This function is not a
|
||
|
|
//! method that can be overriden; it is just a convenience function
|
||
|
|
//! provided with the concept.
|
||
|
|
//!
|
||
|
|
//!
|
||
|
|
//! Example
|
||
|
|
//! -------
|
||
|
|
//! @include example/in.cpp
|
||
|
|
constexpr auto in = hana::infix(hana::flip(hana::contains));
|
||
|
|
BOOST_HANA_NAMESPACE_END
|
||
|
|
|
||
|
|
#endif // !BOOST_HANA_FWD_CONTAINS_HPP
|