/usr/include/range/v3/action/stride.hpp is in librange-v3-dev 0.3.5-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// Range v3 library
//
// Copyright Eric Niebler 2013-present
//
// Use, modification and distribution is subject to the
// Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// Project home: https://github.com/ericniebler/range-v3
//
#ifndef RANGES_V3_ACTION_STRIDE_HPP
#define RANGES_V3_ACTION_STRIDE_HPP
#include <functional>
#include <range/v3/range_fwd.hpp>
#include <range/v3/action/action.hpp>
#include <range/v3/action/erase.hpp>
#include <range/v3/utility/functional.hpp>
#include <range/v3/utility/iterator_concepts.hpp>
#include <range/v3/utility/iterator_traits.hpp>
#include <range/v3/utility/static_const.hpp>
namespace ranges
{
inline namespace v3
{
/// \addtogroup group-actions
/// @{
namespace action
{
struct stride_fn
{
private:
friend action_access;
template<typename D, CONCEPT_REQUIRES_(Integral<D>())>
static auto bind(stride_fn stride, D step)
RANGES_DECLTYPE_AUTO_RETURN
(
std::bind(stride, std::placeholders::_1, step)
)
public:
struct ConceptImpl
{
template<typename Rng, typename T,
typename I = iterator_t<Rng>,
typename S = sentinel_t<Rng>,
typename D = range_difference_type_t<Rng>>
auto requires_() -> decltype(
concepts::valid_expr(
concepts::model_of<concepts::ForwardRange, Rng>(),
concepts::model_of<concepts::ErasableRange, Rng, I, S>(),
concepts::model_of<concepts::ConvertibleTo, T, D>(),
concepts::is_true(Permutable<I>())
));
};
template<typename Rng, typename T>
using Concept = concepts::models<ConceptImpl, Rng, T>;
template<typename Rng, typename D = range_difference_type_t<Rng>,
CONCEPT_REQUIRES_(Concept<Rng, D>())>
Rng operator()(Rng && rng, range_difference_type_t<Rng> const step) const
{
using I = iterator_t<Rng>;
using S = sentinel_t<Rng>;
RANGES_EXPECT(0 < step);
if(1 < step)
{
I begin = ranges::begin(rng);
S const end = ranges::end(rng);
if(begin != end)
{
for(I i = ranges::next(++begin, step-1, end); i != end;
advance(i, step, end), ++begin)
{
*begin = iter_move(i);
}
}
ranges::action::erase(rng, begin, end);
}
return static_cast<Rng&&>(rng);
}
#ifndef RANGES_DOXYGEN_INVOKED
template<typename Rng, typename T,
CONCEPT_REQUIRES_(!Concept<Rng, T>())>
void operator()(Rng &&, T &&) const
{
CONCEPT_ASSERT_MSG(ForwardRange<Rng>(),
"The object on which action::stride operates must be a model of the "
"ForwardRange concept.");
using I = iterator_t<Rng>;
using S = sentinel_t<Rng>;
CONCEPT_ASSERT_MSG(ErasableRange<Rng, I, S>(),
"The object on which action::stride operates must allow element removal.");
CONCEPT_ASSERT_MSG(ConvertibleTo<T, range_difference_type_t<Rng>>(),
"The stride argument to action::stride must be convertible to the range's "
"difference type.");
CONCEPT_ASSERT_MSG(Permutable<I>(),
"The iterator type of the range passed to action::stride must allow its "
"elements to be permutaed; that is, the values must be movable and the "
"iterator must be mutable.");
}
#endif
};
/// \ingroup group-actions
/// \relates stride_fn
/// \sa action
RANGES_INLINE_VARIABLE(action<stride_fn>, stride)
}
/// @}
}
}
#endif
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