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libexpr: Use C++20 heterogeneous lookup for RegexCache

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This commit is contained in:
Sergei Zimmerman 2025-05-04 16:03:57 +00:00
parent 86bf01bc84
commit 36c583dae0
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2 changed files with 44 additions and 5 deletions
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14
src/libexpr/primops.cc
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@ -4311,9 +4311,7 @@ struct RegexCache
{
struct State
{
// TODO use C++20 transparent comparison when available
std::unordered_map<std::string_view, std::regex> cache;
std::list<std::string> keys;
std::unordered_map<std::string, std::regex, StringViewHash, std::equal_to<>> cache;
};
Sync<State> state_;
@ -4324,8 +4322,14 @@ struct RegexCache
auto it = state->cache.find(re);
if (it != state->cache.end())
return it->second;
state->keys.emplace_back(re);
return state->cache.emplace(state->keys.back(), std::regex(state->keys.back(), std::regex::extended)).first->second;
/* No std::regex constructor overload from std::string_view, but can be constructed
from a pointer + size or an iterator range. */
return state->cache
.emplace(
std::piecewise_construct,
std::forward_as_tuple(re),
std::forward_as_tuple(/*s=*/re.data(), /*count=*/re.size(), std::regex::extended))
.first->second;
}
};