search_server: parallel

tuple<vector<string>, DocumentStatus> SearchServer::MatchDocument(
    const std::execution::parallel_policy& policy,
    const string &raw_query,
    int document_id
) const
{
    const auto query = ParseQuery(raw_query);
    vector<string> matched_words(query.plus_words.size());
    vector<const string*> minus_words(query.minus_words.size());

    std::transform(
        policy,
        query.minus_words.begin(),
        query.minus_words.end(),
        minus_words.begin(),
        [](const string &word){return &word;}
    );
    if(
        any_of(
            policy, minus_words.begin(), minus_words.end(),
            [&](auto& word){
                //std::cout << word << endl;
                return word_to_document_freqs_.at(*word).count(document_id);
            }
        )
    )
    {
        //cout << "!"<<endl;
        return {vector<string>{}, documents_.at(document_id).status};
    }

    vector<string> plus_words(
        query.plus_words.begin(),query.plus_words.end()
    );
    {
        auto it_end = copy_if(
            policy,
            plus_words.begin(),
            plus_words.end(),
            matched_words.begin(),
            [&](string& word){
                return word_to_document_freqs_.at(word).count(document_id);
            }
        );
        matched_words.erase(it_end, matched_words.end());
    }
    sort(policy, matched_words.begin(),matched_words.end());
    {
        auto it_end = unique(
            policy,
            matched_words.begin(),
            matched_words.end()
        );
        matched_words.erase(it_end, matched_words.end());
    }
    return {matched_words, documents_.at(document_id).status};
}