sstream-driven lexical cast

lexical_cast.hpp

#pragma once
#include <sstream>
#include <string>

namespace detail {

template <typename T, typename U>
class LexicalCast {
 public:
  T operator()(U const& u) {
    return string_to_t(u_to_string(u));
  }
 private:
  LexicalCast<T, std::string> string_to_t;
  LexicalCast<std::string, U> u_to_string;
};

template <typename T>
class LexicalCast<std::string, T> {
 public:
  std::string operator()(T const& t) {
    std::ostringstream os;
    os.exceptions(os.failbit | os.badbit);
    os << t;
    return os.str();
  }
};

template <typename T>
class LexicalCast<T, std::string> {
 public:
  T operator()(std::string const& s) {
    T t;
    std::istringstream is(s);
    is.exceptions(is.failbit | is.badbit);
    is >> t;
    return t;
  }
};

}  // namespace detail

template <typename T, typename U>
T lexical_cast(U&& value) {
  static detail::LexicalCast<T, U> cast;
  return cast(std::forward<U>(value));
}