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Use a heap instead of sorting to gather the best shell-candidates matches

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O(n + k * log n) (with k = 100 here) instead of O(n log n), much faster
with many candidates.
This commit is contained in:
Maxime Coste 2016-08-30 13:42:29 +01:00
parent 551263c564
commit b6cab458ed
1 changed files with 13 additions and 4 deletions
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17
src/commands.cc
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@ -904,11 +904,20 @@ void define_command(const ParametersParser& parser, Context& context, const Shel
if (RankedMatch match{candidate.first, candidate.second, query, query_letters})
matches.push_back(match);
}
std::sort(matches.begin(), matches.end());
matches.erase(std::unique(matches.begin(), matches.end()), matches.end());
constexpr size_t max_count = 100;
// Gather best max_count matches
auto greater = [](const RankedMatch& lhs,
const RankedMatch& rhs) { return rhs < lhs; };
auto first = matches.begin(), last = matches.end();
std::make_heap(first, last, greater);
CandidateList res;
for (auto& m : matches)
res.push_back(m.candidate().str());
while(res.size() < max_count and first != last)
{
if (res.empty() or res.back() != first->candidate())
res.push_back(first->candidate().str());
std::pop_heap(first, last--, greater);
}
return Completions{ 0_byte, pos_in_token, std::move(res) };
};