static I impl(I begin, I end, C pred, P proj, D len, Pair const p, concepts::ForwardIterator *fi)
{
// *begin is known to be false
// len >= 1
if(len == 1)
return begin;
if(len == 2)
{
I tmp = begin;
if(invoke(pred, invoke(proj, *++tmp)))
{
ranges::iter_swap(begin, tmp);
return tmp;
}
return begin;
}
if(len <= p.second)
{ // The buffer is big enough to use
// Move the falses into the temporary buffer, and the trues to the front of the line
// Update begin to always point to the end of the trues
auto tmpbuf = make_raw_buffer(p.first);
auto buf = tmpbuf.begin();
*buf = iter_move(begin);
++buf;
auto res = partition_copy(make_move_iterator(next(begin)),
make_move_sentinel(end), begin, buf, std::ref(pred), std::ref(proj));
// All trues now at start of range, all falses in buffer
// Move falses back into range, but don't mess up begin which points to first false
ranges::move(p.first, res.out2().base().base(), res.out1());
// h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
return res.out1();
}
// Else not enough buffer, do in place
// len >= 3
D half = len / 2; // half >= 2
I middle = next(begin, half);
// recurse on [begin, middle), *begin know to be false
// F?????????????????
// f m l
I begin_false = stable_partition_fn::impl(begin, middle, pred, proj, half, p, fi);
// TTTFFFFF??????????
// f ff m l
// recurse on [middle, end], except increase middle until *(middle) is false, *end know to be true
I m1 = middle;
D len_half = len - half;
while(invoke(pred, invoke(proj, *m1)))
{
if(++m1 == end)
return ranges::rotate(begin_false, middle, end).begin();
--len_half;
}
// TTTFFFFFTTTF??????
// f ff m m1 l
I end_false = stable_partition_fn::impl(m1, end, pred, proj, len_half, p, fi);
// TTTFFFFFTTTTTFFFFF
// f ff m sf l
return ranges::rotate(begin_false, middle, end_false).begin();
// TTTTTTTTFFFFFFFFFF
// |
}
static I impl(I begin, I end, C pred, P proj, D len, Pair p,
detail::bidirectional_iterator_tag_ bi)
{
// *begin is known to be false
// *end is known to be true
// len >= 2
if(len == 2)
{
ranges::iter_swap(begin, end);
return end;
}
if(len == 3)
{
I tmp = begin;
if(invoke(pred, invoke(proj, *++tmp)))
{
ranges::iter_swap(begin, tmp);
ranges::iter_swap(tmp, end);
return end;
}
ranges::iter_swap(tmp, end);
ranges::iter_swap(begin, tmp);
return tmp;
}
if(len <= p.second)
{ // The buffer is big enough to use
// Move the falses into the temporary buffer, and the trues to the front
// of the line Update begin to always point to the end of the trues
auto tmpbuf = ranges::make_raw_buffer(p.first);
auto buf = tmpbuf.begin();
*buf = iter_move(begin);
++buf;
auto res = partition_copy(make_move_iterator(next(begin)),
make_move_sentinel(end),
begin,
buf,
std::ref(pred),
std::ref(proj));
begin = res.out1;
// move *end, known to be true
*begin = iter_move(res.in);
++begin;
// All trues now at start of range, all falses in buffer
// Move falses back into range, but don't mess up begin which points to
// first false
ranges::move(p.first, res.out2.base().base(), begin);
// h destructs moved-from values out of the temp buffer, but doesn't
// deallocate buffer
return begin;
}
// Else not enough buffer, do in place
// len >= 4
I middle = begin;
D half = len / 2; // half >= 2
advance(middle, half);
// recurse on [begin, middle-1], except reduce middle-1 until *(middle-1) is
// true, *begin know to be false F????????????????T f m l
I m1 = middle;
I begin_false = begin;
D len_half = half;
while(!invoke(pred, invoke(proj, *--m1)))
{
if(m1 == begin)
goto first_half_done;
--len_half;
}
// F???TFFF?????????T
// f m1 m l
begin_false =
stable_partition_fn::impl(begin, m1, pred, proj, len_half, p, bi);
first_half_done:
// TTTFFFFF?????????T
// f ff m l
// recurse on [middle, end], except increase middle until *(middle) is false,
// *end know to be true
m1 = middle;
len_half = len - half;
while(invoke(pred, invoke(proj, *m1)))
{
if(++m1 == end)
return ranges::rotate(begin_false, middle, ++end).begin();
--len_half;
}
// TTTFFFFFTTTF?????T
// f ff m m1 l
I end_false = stable_partition_fn::impl(m1, end, pred, proj, len_half, p, bi);
// TTTFFFFFTTTTTFFFFF
// f ff m sf l
return ranges::rotate(begin_false, middle, end_false).begin();
// TTTTTTTTFFFFFFFFFF
// |
}
static I impl(I begin, I end, C pred, P proj, D len, Pair p, concepts::ForwardIterator *fi)
{
// *begin is known to be false
// len >= 1
if (len == 1)
return begin;
if(len == 2)
{
I tmp = begin;
if(pred(proj(*++tmp)))
{
ranges::iter_swap(begin, tmp);
return tmp;
}
return begin;
}
if(len <= p.second)
{ // The buffer is big enough to use
using value_type = iterator_value_t<I>;
std::unique_ptr<value_type, detail::destroy_n<value_type>> h{p.first, {}};
// Move the falses into the temporary buffer, and the trues to the front of the line
// Update begin to always point to the end of the trues
auto buf = ranges::make_counted_raw_storage_iterator(p.first, h.get_deleter());
using MI = std::move_iterator<I>;
*buf = std::move(*begin);
++buf;
auto res = partition_copy(MI{next(begin)}, MI{end}, begin, buf, std::ref(pred), std::ref(proj));
// All trues now at start of range, all falses in buffer
// Move falses back into range, but don't mess up begin which points to first false
ranges::move(p.first, std::get<2>(res).base().base(), std::get<1>(res));
// h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
return std::get<1>(res);
}
// Else not enough buffer, do in place
// len >= 3
D half = len / 2; // half >= 2
I middle = next(begin, half);
// recurse on [begin, middle), *begin know to be false
// F?????????????????
// f m l
I begin_false = stable_partition_fn::impl(begin, middle, pred, proj, half, p, fi);
// TTTFFFFF??????????
// f ff m l
// recurse on [middle, end], except increase middle until *(middle) is false, *end know to be true
I m1 = middle;
D len_half = len - half;
while(pred(proj(*m1)))
{
if(++m1 == end)
return ranges::rotate(begin_false, middle, end).begin();
--len_half;
}
// TTTFFFFFTTTF??????
// f ff m m1 l
I end_false = stable_partition_fn::impl(m1, end, pred, proj, len_half, p, fi);
// TTTFFFFFTTTTTFFFFF
// f ff m sf l
return ranges::rotate(begin_false, middle, end_false).begin();
// TTTTTTTTFFFFFFFFFF
// |
}