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Avoid potentially quadratic runtime when updating selections after modification

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LineRangeSet::add_range() calls Vector::erase() in a loop over the
same vector. This could cause performance problems when there are many
selections. Fix this by only calling Vector::erase() once.  I didn't
measure anything because my benchmark is dominated by another issue
(see next commit).

LineRangeSet::remove_range() also has a suspicious call to erase()
but that one is only used in test code, so it doesn't matter.
This commit is contained in:
Johannes Altmanninger 2022-08-17 00:11:26 +02:00
parent 674053935d
commit a33ec8dc80
1 changed files with 7 additions and 6 deletions
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11
src/line_modification.cc
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@ -147,26 +147,27 @@ void LineRangeSet::update(ConstArrayView<LineModification> modifs)
void LineRangeSet::add_range(LineRange range, FunctionRef<void (LineRange)> on_new_range)
{
auto it = std::lower_bound(begin(), end(), range.begin,
auto insert_at = std::lower_bound(begin(), end(), range.begin,
[](LineRange range, LineCount line) { return range.end < line; });
if (it == end() or it->begin > range.end)
if (insert_at == end() or insert_at->begin > range.end)
on_new_range(range);
else
{
auto pos = range.begin;
while (it != end() and it->begin <= range.end)
auto it = insert_at;
for (; it != end() and it->begin <= range.end; ++it)
{
if (pos < it->begin)
on_new_range({pos, it->begin});
range = LineRange{std::min(range.begin, it->begin), std::max(range.end, it->end)};
pos = it->end;
it = erase(it);
}
insert_at = erase(insert_at, it);
if (pos < range.end)
on_new_range({pos, range.end});
}
insert(it, range);
insert(insert_at, range);
}
void LineRangeSet::remove_range(LineRange range)