#include <iostream>
#include <sstream>
#include <string>
#include <algorithm>
// This is the type that will hold all the strings.
// Each enumerateenumeration type will declare its own specialization.
// Any enum that does not have a specialization will generate a compiler error
// indicating that there is no definition of this variable (as there should be
// be no definition of a generic version).
template<typename T>
struct enumStrings
{
static char const* data[];
};
// This is a utility type.
// CretedCreated automatically. Should not be used directly.
template<typename T>
struct enumRefHolder
{
T& enumVal;
enumRefHolder(T& enumVal): enumVal(enumVal) {}
};
template<typename T>
struct enumConstRefHolder
{
T const& enumVal;
enumConstRefHolder(T const& enumVal): enumVal(enumVal) {}
};
// The next tootwo functions do the actual work of reading/writtinwriting an
// enum as a string.
template<typename T>
std::ostream& operator<<(std::ostream& str, enumConstRefHolder<T> const& data)
{
return str << enumStrings<T>::data[data.enumVal];
}
template<typename T>
std::istream& operator>>(std::istream& str, enumRefHolder<T> const& data)
{
std::string value;
str >> value;
// These two can be made easier to read in C++11
// using std::begin() and std::end()
//
static auto begin = std::begin(enumStrings<T>::data);
static auto end = std::end(enumStrings<T>::data);
auto find = std::find(begin, end, value);
if (find != end)
{
data.enumVal = static_cast<T>(std::distance(begin, find));
}
return str;
}
// This is the public interface:
// use the ability of function to deucededuce their template type without
// being explicitly told to create the correct type of enumRefHolder<T>
template<typename T>
enumConstRefHolder<T> enumToString(T const& e) {return enumConstRefHolder<T>(e);}
template<typename T>
enumRefHolder<T> enumFromString(T& e) {return enumRefHolder<T>(e);}