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ilpropheta/Efficient std::map get or insert.cpp Secret

Last active July 19, 2016 17:58
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Efficient std::map get or insert.cpp
template<typename Gen>
ValueType fetch_or_insert(const Key& key, Gen g)
{
const auto lb = data.lower_bound(key);
if (lb != end(data) && !(data.key_comp()(key, lb->first)))
{
return lb->second;
}
return data.emplace_hint(lb, key, g())->second;
}
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