Was thinking about extending the C switch beyond integers. Here is what it came to - will gladly accept any suggestions for improvement. Note: "Any class" in the title is not quite correct - the class should have equal operator and hash function to be used in this switch.

#include <iostream>
#include <unordered_map>
#include <string>
#include <functional>

template<typename T>
using xmap = std::unordered_map<T, std::function<void()>>;

template<typename T>
void xwitch(const T& var, const xmap<T>& m, std::function<void()> otherwise = []() {})
{
    auto it = m.find(var);
    if (it == m.end())
        otherwise();
    else
        it->second();
}

#define SWITCH(var) xwitch(var, xmap<std::remove_const<decltype(str)>::type> {
#define END_SWITCH });
#define CASE {
#define THEN , []() {
#define END_CASE } },
#define DEFAULT }, []() {

int main()
{
    const std::string str{ "Second string" };
    using namespace std::string_literals;
    SWITCH(str)
        CASE "First string"s THEN std::cout << "First string matched\n"; END_CASE
        CASE "Second string"s THEN std::cout << "Second string matched\n"; END_CASE
        CASE "Third string"s THEN std::cout << "Third string matched\n"; END_CASE
    END_SWITCH
    
    SWITCH("unmatched"s)
        CASE "First string"s THEN std::cout << "First string matched\n"; END_CASE
        CASE "Second string"s THEN std::cout << "Second string matched\n"; END_CASE
        CASE "Third string"s THEN std::cout << "Third string matched\n"; END_CASE
        DEFAULT std::cout << "No matches\n";
    END_SWITCH
}