#ifndef GENERS_IOISCONTAINER_HH_
#define GENERS_IOISCONTAINER_HH_

#include <string>

namespace gs {
  // In the following template, enum "IsContainer" is evaluated to 1
  // at compile time if T has T::value_type typedef
  template <typename T>
  class IOIsContainer {
  private:
    typedef char One;
    typedef struct {
      char a[2];
    } Two;
    template <typename C>
    static One test(typename C::value_type const *);
    template <typename C>
    static Two test(...);

  public:
    enum { value = sizeof(IOIsContainer<T>::template test<T>(nullptr)) == 1 };
  };

  // Char strings get a special treatment
  template <>
  class IOIsContainer<std::string> {
  public:
    enum { value = 0 };
  };

  template <>
  class IOIsContainer<const std::string> {
  public:
    enum { value = 0 };
  };

  template <>
  class IOIsContainer<volatile std::string> {
  public:
    enum { value = 0 };
  };

  template <>
  class IOIsContainer<const volatile std::string> {
  public:
    enum { value = 0 };
  };
}  // namespace gs

#endif  // GENERS_IOISCONTAINER_HH_