/usr/include/boost/hana/back.hpp is in libboost1.65-dev 1.65.1+dfsg-0ubuntu5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | /*!
@file
Defines `boost::hana::back`.
@copyright Louis Dionne 2013-2017
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_BACK_HPP
#define BOOST_HANA_BACK_HPP
#include <boost/hana/fwd/back.hpp>
#include <boost/hana/at.hpp>
#include <boost/hana/concept/iterable.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/dispatch.hpp>
#include <boost/hana/length.hpp>
#include <cstddef>
BOOST_HANA_NAMESPACE_BEGIN
//! @cond
template <typename Xs>
constexpr decltype(auto) back_t::operator()(Xs&& xs) const {
using It = typename hana::tag_of<Xs>::type;
using Back = BOOST_HANA_DISPATCH_IF(back_impl<It>,
hana::Iterable<It>::value
);
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::Iterable<It>::value,
"hana::back(xs) requires 'xs' to be an Iterable");
#endif
return Back::apply(static_cast<Xs&&>(xs));
}
//! @endcond
template <typename It, bool condition>
struct back_impl<It, when<condition>> : default_ {
template <typename Xs>
static constexpr decltype(auto) apply(Xs&& xs) {
constexpr std::size_t len = decltype(hana::length(xs))::value;
static_assert(len > 0, "hana::back(xs) requires 'xs' to be non-empty");
return hana::at_c<len - 1>(static_cast<Xs&&>(xs));
}
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_BACK_HPP
|