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/// \file
// 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
//
// Copyright (c) 1994
// Hewlett-Packard Company
//
// Permission to use, copy, modify, distribute and sell this software
// and its documentation for any purpose is hereby granted without fee,
// provided that the above copyright notice appear in all copies and
// that both that copyright notice and this permission notice appear
// in supporting documentation. Hewlett-Packard Company makes no
// representations about the suitability of this software for any
// purpose. It is provided "as is" without express or implied warranty.
//
// Copyright (c) 1996
// Silicon Graphics Computer Systems, Inc.
//
// Permission to use, copy, modify, distribute and sell this software
// and its documentation for any purpose is hereby granted without fee,
// provided that the above copyright notice appear in all copies and
// that both that copyright notice and this permission notice appear
// in supporting documentation. Silicon Graphics makes no
// representations about the suitability of this software for any
// purpose. It is provided "as is" without express or implied warranty.
//
#ifndef RANGES_V3_ALGORITHM_STABLE_SORT_HPP
#define RANGES_V3_ALGORITHM_STABLE_SORT_HPP
#include <functional>
#include <iterator>
#include <memory>
#include <range/v3/range_fwd.hpp>
#include <range/v3/algorithm/inplace_merge.hpp>
#include <range/v3/algorithm/merge.hpp>
#include <range/v3/algorithm/min.hpp>
#include <range/v3/algorithm/sort.hpp>
#include <range/v3/functional/comparisons.hpp>
#include <range/v3/functional/identity.hpp>
#include <range/v3/iterator/concepts.hpp>
#include <range/v3/iterator/move_iterators.hpp>
#include <range/v3/iterator/operations.hpp>
#include <range/v3/iterator/traits.hpp>
#include <range/v3/range/access.hpp>
#include <range/v3/range/concepts.hpp>
#include <range/v3/range/dangling.hpp>
#include <range/v3/range/traits.hpp>
#include <range/v3/utility/memory.hpp>
#include <range/v3/utility/static_const.hpp>
#include <range/v3/detail/prologue.hpp>
namespace ranges
{
/// \addtogroup group-algorithms
/// @{
/// \cond
namespace detail
{
template<typename I, typename C, typename P>
void inplace_stable_sort(I first, I last, C & pred, P & proj)
{
if(last - first < 15)
return detail::insertion_sort(first, last, pred, proj), void();
I middle = first + (last - first) / 2;
detail::inplace_stable_sort(first, middle, pred, proj);
detail::inplace_stable_sort(middle, last, pred, proj);
detail::inplace_merge_no_buffer(first,
middle,
last,
middle - first,
last - middle,
std::ref(pred),
std::ref(proj));
}
template<typename I1, typename I2, typename D, typename C, typename P>
void merge_sort_loop(I1 first, I1 last, I2 result, D step_size, C & pred,
P & proj)
{
D two_step = 2 * step_size;
while(last - first >= two_step)
{
result = merge(make_move_iterator(first),
make_move_iterator(first + step_size),
make_move_iterator(first + step_size),
make_move_iterator(first + two_step),
result,
std::ref(pred),
std::ref(proj),
std::ref(proj))
.out;
first += two_step;
}
step_size = ranges::min(D(last - first), step_size);
merge(make_move_iterator(first),
make_move_iterator(first + step_size),
make_move_iterator(first + step_size),
make_move_iterator(last),
result,
std::ref(pred),
std::ref(proj),
std::ref(proj));
}
constexpr int merge_sort_chunk_size()
{
return 7;
}
template<typename I, typename D, typename C, typename P>
void chunk_insertion_sort(I first, I last, D chunk_size, C & pred, P & proj)
{
while(last - first >= chunk_size)
{
detail::insertion_sort(first, first + chunk_size, pred, proj);
first += chunk_size;
}
detail::insertion_sort(first, last, pred, proj);
}
// buffer points to raw memory, we create objects, and then restore the buffer to
// raw memory by destroying the objects on return.
template<typename I, typename V, typename C, typename P>
void merge_sort_with_buffer(I first, I last, V * buffer, C & pred, P & proj)
{
iter_difference_t<I> len = last - first,
step_size = detail::merge_sort_chunk_size();
detail::chunk_insertion_sort(first, last, step_size, pred, proj);
if(step_size >= len)
return;
// The first call to merge_sort_loop moves into raw storage. Construct
// on-demand and keep track of how many objects we need to destroy.
V * buffer_end = buffer + static_cast<std::ptrdiff_t>(len);
auto tmpbuf = make_raw_buffer(buffer);
detail::merge_sort_loop(first, last, tmpbuf.begin(), step_size, pred, proj);
step_size *= 2;
loop:
detail::merge_sort_loop(
buffer, buffer_end, first, (std::ptrdiff_t)step_size, pred, proj);
step_size *= 2;
if(step_size >= len)
return;
detail::merge_sort_loop(first, last, buffer, step_size, pred, proj);
step_size *= 2;
goto loop;
}
// buffer points to raw memory
template<typename I, typename V, typename C, typename P>
void stable_sort_adaptive(I first, I last, V * buffer, std::ptrdiff_t buffer_size,
C & pred, P & proj)
{
iter_difference_t<I> len = (last - first + 1) / 2;
I middle = first + len;
if(len > buffer_size)
{
detail::stable_sort_adaptive(
first, middle, buffer, buffer_size, pred, proj);
detail::stable_sort_adaptive(
middle, last, buffer, buffer_size, pred, proj);
}
else
{
detail::merge_sort_with_buffer(first, middle, buffer, pred, proj);
detail::merge_sort_with_buffer(middle, last, buffer, pred, proj);
}
detail::merge_adaptive(first,
middle,
last,
middle - first,
last - middle,
buffer,
buffer_size,
std::ref(pred),
std::ref(proj));
}
} // namespace detail
/// \endcond
RANGES_FUNC_BEGIN(stable_sort)
/// \brief function template \c stable_sort
template(typename I, typename S, typename C = less, typename P = identity)(
requires sortable<I, C, P> AND random_access_iterator<I> AND
sentinel_for<S, I>)
I RANGES_FUNC(stable_sort)(I first, S end_, C pred = C{}, P proj = P{})
{
I last = ranges::next(first, end_);
using D = iter_difference_t<I>;
using V = iter_value_t<I>;
D len = last - first;
auto buf =
len > 256 ? detail::get_temporary_buffer<V>(len) : detail::value_init{};
std::unique_ptr<V, detail::return_temporary_buffer> h{buf.first};
if(buf.first == nullptr)
detail::inplace_stable_sort(first, last, pred, proj);
else
detail::stable_sort_adaptive(
first, last, buf.first, buf.second, pred, proj);
return last;
}
/// \overload
template(typename Rng, typename C = less, typename P = identity)(
requires sortable<iterator_t<Rng>, C, P> AND random_access_range<Rng>)
borrowed_iterator_t<Rng> //
RANGES_FUNC(stable_sort)(Rng && rng, C pred = C{}, P proj = P{}) //
{
return (*this)(begin(rng), end(rng), std::move(pred), std::move(proj));
}
RANGES_FUNC_END(stable_sort)
namespace cpp20
{
using ranges::stable_sort;
}
/// @}
} // namespace ranges
#include <range/v3/detail/epilogue.hpp>
#endif
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