stay safe

#pragma once
#include <map>
#include <stdexcept>
#include <exception>

template <class Iterator, class Predicate, class Functor>
void TransformIf(Iterator first, Iterator last, Predicate p, Functor f) {
    std::map<int, decltype(*first)> prev_state;
    int cnt = 0;
    for (auto i = first; i != last; ++i) {
        try {
            if (p(*i)) {
                try {
                    log.emplace_back(cnt, *i);
                } catch (std::exception& e) { //catching copy
                    try {
                        f(*i);
                    } catch (std::exception &u) { //catching f
                        throw u;
                    }
                }
            }
            cnt++;
        } catch(std::exception& e) { //catching p
            auto it = first;
            int in = 0;
            for (int j = 0; j != cnt && in < log.size(); ++j) {
                if (log[in].first == j) {
                    try {
                        *it = log[in].second;
                    } catch(std::exception& u) { //catching copy
                        throw u;
                    }
                }
                ++it;
            }
            throw e;
        }
    }
}