/**
 * Clayton Cafiero
 * CS 2240
 * 2021-Jan-22
 */

/**
 * We want `<optional>` so we can use in our hash table,
 * i.e. some elements have values, others do not, hence
 * `nullopt`. We've been using C++ 14 standard so far for
 * this class, and optional was introduced in C++ 17.
 * So here we try to include <experimental/optional> if
 * standard is < 17, if that fails we go with C++ version
 * <optional>
 *
 * If this produces errors, go into CMakeLists.txt and change
 * the CMAKE_CXX_STANDARD from 14 to 17.
 *
 * Here also is a valid use case for `using` in a header
 * file. We want `optional`, `nullopt`, and `make_optional`,
 * but these reside in different scopes in C++ 14 vs C++ 17.
 * Hence we apply `using` here, so that the code in our
 * header is portable between 14 and 17. Notice that we don't
 * use the entire namespace, just what we actually use.
 */
#if __cplusplus < 17
#include <experimental/optional>
using std::experimental::optional;
using std::experimental::nullopt;
using std::experimental::make_optional;
#else
#include <optional>
using std::optional;
using std::nullopt;
using std::make_optional;
#endif

#include <vector>
#include <iostream>
#include <string>

optional<int> find(std::vector<std::string>& v, std::string key) {
    for (int i = 0; i < v.size(); ++i) {
        if (v[i] == key) {
            return i;
        }
    }
    return nullopt;
}

int main() {
    std::vector<std::string> v = {"Monday", "Tuesday", "Wednesday", "Thursday",
                                  "Friday", "Saturday", "Sunday"};

    optional<int> i = find(v, "Thursday");
    if (i) {
        std::cout << *i << std::endl;
    }


    i = find(v, "Wombat");
    if (i) {
        // won't print! 'cause "Wombat" is not in our vector
        // and thus find will return nullopt
        std::cout << *i << std::endl;
    }

    return 0;
}