是否可以强制stl设置为重新评估谓词?

考虑以下数据结构和代码。

struct Sentence {
    std::string words;
    int frequency;
    Sentence(std::string words, int frequency) : words(words), frequency(frequency) {}
};
struct SentencePCompare {
    bool operator() (const Sentence* lhs, const Sentence* rhs) const {
        if (lhs->frequency != rhs->frequency) {
            return lhs->frequency > rhs->frequency;
        }
        return lhs->words.compare(rhs->words) < 0;
    }
};
std::set<Sentence*, SentencePCompare> sentencesByFrequency;

int main(){
    Sentence* foo = new Sentence("foo", 1);
    Sentence* bar = new Sentence("bar", 2);
    sentencesByFrequency.insert(foo);
    sentencesByFrequency.insert(bar);
    for (Sentence* sp : sentencesByFrequency) {
        std::cout << sp->words << std::endl;
    }
    foo->frequency = 5;
    for (Sentence* sp : sentencesByFrequency) {
        std::cout << sp->words << std::endl;
    }
}

上述代码的输出如下。

bar
foo
bar
foo

如我们所料,当集合中指针指向的对象被更新时,集合不会自动重新计算谓词,即使谓词根据指针指向的对象对指针进行排序。

有没有办法强迫 std::set 要重新计算谓词,使顺序再次正确吗?