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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_SORT_HPP
#define RANGES_V3_ALGORITHM_SORT_HPP
#include <range/v3/range_fwd.hpp>
#include <range/v3/algorithm/heap_algorithm.hpp>
#include <range/v3/algorithm/move_backward.hpp>
#include <range/v3/algorithm/partial_sort.hpp>
#include <range/v3/functional/comparisons.hpp>
#include <range/v3/functional/identity.hpp>
#include <range/v3/functional/invoke.hpp>
#include <range/v3/iterator/concepts.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/static_const.hpp>
#include <range/v3/detail/prologue.hpp>
namespace ranges
{
/// \cond
namespace detail
{
template<typename I, typename C, typename P>
inline constexpr I unguarded_partition(I first, I last, C & pred, P & proj)
{
I mid = first + (last - first) / 2, penultimate = ranges::prev(last);
auto &&x = *first, &&y = *mid, &&z = *penultimate;
auto &&a = invoke(proj, (decltype(x) &&)x),
&&b = invoke(proj, (decltype(y) &&)y),
&&c = invoke(proj, (decltype(z) &&)z);
// Find the median:
I pivot_pnt =
invoke(pred, a, b)
? (invoke(pred, b, c) ? mid
: (invoke(pred, a, c) ? penultimate : first))
: (invoke(pred, a, c) ? first
: (invoke(pred, b, c) ? penultimate : mid));
// Do the partition:
while(true)
{
auto && v = *pivot_pnt;
auto && pivot = invoke(proj, (decltype(v) &&)v);
while(invoke(pred, invoke(proj, *first), pivot))
++first;
--last;
while(invoke(pred, pivot, invoke(proj, *last)))
--last;
if(!(first < last))
return first;
ranges::iter_swap(first, last);
pivot_pnt =
pivot_pnt == first ? last : (pivot_pnt == last ? first : pivot_pnt);
++first;
}
}
template<typename I, typename C, typename P>
inline constexpr void unguarded_linear_insert(I last,
iter_value_t<I> val,
C & pred,
P & proj)
{
I next_ = prev(last);
while(invoke(pred, invoke(proj, val), invoke(proj, *next_)))
{
*last = iter_move(next_);
last = next_;
--next_;
}
*last = std::move(val);
}
template<typename I, typename C, typename P>
inline constexpr void linear_insert(I first, I last, C & pred, P & proj)
{
iter_value_t<I> val = iter_move(last);
if(invoke(pred, invoke(proj, val), invoke(proj, *first)))
{
move_backward(first, last, last + 1);
*first = std::move(val);
}
else
detail::unguarded_linear_insert(last, std::move(val), pred, proj);
}
template<typename I, typename C, typename P>
inline constexpr void insertion_sort(I first, I last, C & pred, P & proj)
{
if(first == last)
return;
for(I i = next(first); i != last; ++i)
detail::linear_insert(first, i, pred, proj);
}
template<typename I, typename C, typename P>
inline constexpr void unguarded_insertion_sort(I first, I last, C & pred, P & proj)
{
for(I i = first; i != last; ++i)
detail::unguarded_linear_insert(i, iter_move(i), pred, proj);
}
constexpr int introsort_threshold()
{
return 16;
}
template<typename I, typename C, typename P>
inline constexpr void final_insertion_sort(I first, I last, C & pred, P & proj)
{
if(last - first > detail::introsort_threshold())
{
detail::insertion_sort(
first, first + detail::introsort_threshold(), pred, proj);
detail::unguarded_insertion_sort(
first + detail::introsort_threshold(), last, pred, proj);
}
else
detail::insertion_sort(first, last, pred, proj);
}
template<typename Size>
inline constexpr Size log2(Size n)
{
Size k = 0;
for(; n != 1; n >>= 1)
++k;
return k;
}
template<typename I, typename Size, typename C, typename P>
inline constexpr void introsort_loop(I first, I last, Size depth_limit, C & pred, P & proj)
{
while(last - first > detail::introsort_threshold())
{
if(depth_limit == 0)
return partial_sort(
first, last, last, std::ref(pred), std::ref(proj)),
void();
I cut = detail::unguarded_partition(first, last, pred, proj);
detail::introsort_loop(cut, last, --depth_limit, pred, proj);
last = cut;
}
}
} // namespace detail
/// \endcond
/// \addtogroup group-algorithms
/// @{
// Introsort: Quicksort to a certain depth, then Heapsort. Insertion
// sort below a certain threshold.
// TODO Forward iterators, like EoP?
RANGES_FUNC_BEGIN(sort)
/// \brief function template \c 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>)
constexpr I RANGES_FUNC(sort)(I first, S end_, C pred = C{}, P proj = P{})
{
I last = ranges::next(first, std::move(end_));
if(first != last)
{
detail::introsort_loop(
first, last, detail::log2(last - first) * 2, pred, proj);
detail::final_insertion_sort(first, last, 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>)
constexpr borrowed_iterator_t<Rng> //
RANGES_FUNC(sort)(Rng && rng, C pred = C{}, P proj = P{}) //
{
return (*this)(begin(rng), end(rng), std::move(pred), std::move(proj));
}
RANGES_FUNC_END(sort)
namespace cpp20
{
using ranges::sort;
}
/// @}
} // namespace ranges
#include <range/v3/detail/epilogue.hpp>
#endif
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