type_traits.h

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#ifndef DMLC_TYPE_TRAITS_H_
#define DMLC_TYPE_TRAITS_H_
 
#include "./base.h"
#if DMLC_USE_CXX11
#include <type_traits>
#endif
#include <string>
 
namespace dmlc {
template<typename T>
struct is_pod {
#if DMLC_USE_CXX11
  static const bool value = std::is_pod<T>::value;
#else
  static const bool value = false;
#endif
};
 
 
template<typename T>
struct is_integral {
#if DMLC_USE_CXX11
  static const bool value = std::is_integral<T>::value;
#else
  static const bool value = false;
#endif
};
 
template<typename T>
struct is_floating_point {
#if DMLC_USE_CXX11
  static const bool value = std::is_floating_point<T>::value;
#else
  static const bool value = false;
#endif
};
 
template<typename T>
struct is_arithmetic {
#if DMLC_USE_CXX11
  static const bool value = std::is_arithmetic<T>::value;
#else
  static const bool value = (dmlc::is_integral<T>::value ||
                             dmlc::is_floating_point<T>::value);
#endif
};
 
template<typename T>
struct type_name_helper {
  static inline std::string value() {
    return "";
  }
};
 
template<typename T>
inline std::string type_name() {
  return type_name_helper<T>::value();
}
 
template<typename T>
struct has_saveload {
  static const bool value = false;
};
 
template<bool cond, typename Then, typename Else>
struct IfThenElseType;
 
#define DMLC_DECLARE_TRAITS(Trait, Type, Value)       \
  template<>                                          \
  struct Trait<Type> {                                \
    static const bool value = Value;                  \
  }
 
#define DMLC_DECLARE_TYPE_NAME(Type, Name)            \
  template<>                                          \
  struct type_name_helper<Type> {                     \
    static inline std::string value() {               \
      return Name;                                    \
    }                                                 \
  }
 
// declare special traits when C++11 is not available
#if DMLC_USE_CXX11 == 0
DMLC_DECLARE_TRAITS(is_pod, char, true);
DMLC_DECLARE_TRAITS(is_pod, int8_t, true);
DMLC_DECLARE_TRAITS(is_pod, int16_t, true);
DMLC_DECLARE_TRAITS(is_pod, int32_t, true);
DMLC_DECLARE_TRAITS(is_pod, int64_t, true);
DMLC_DECLARE_TRAITS(is_pod, uint8_t, true);
DMLC_DECLARE_TRAITS(is_pod, uint16_t, true);
DMLC_DECLARE_TRAITS(is_pod, uint32_t, true);
DMLC_DECLARE_TRAITS(is_pod, uint64_t, true);
DMLC_DECLARE_TRAITS(is_pod, float, true);
DMLC_DECLARE_TRAITS(is_pod, double, true);
 
DMLC_DECLARE_TRAITS(is_integral, char, true);
DMLC_DECLARE_TRAITS(is_integral, int8_t, true);
DMLC_DECLARE_TRAITS(is_integral, int16_t, true);
DMLC_DECLARE_TRAITS(is_integral, int32_t, true);
DMLC_DECLARE_TRAITS(is_integral, int64_t, true);
DMLC_DECLARE_TRAITS(is_integral, uint8_t, true);
DMLC_DECLARE_TRAITS(is_integral, uint16_t, true);
DMLC_DECLARE_TRAITS(is_integral, uint32_t, true);
DMLC_DECLARE_TRAITS(is_integral, uint64_t, true);
 
DMLC_DECLARE_TRAITS(is_floating_point, float, true);
DMLC_DECLARE_TRAITS(is_floating_point, double, true);
 
#endif
 
DMLC_DECLARE_TYPE_NAME(float, "float");
DMLC_DECLARE_TYPE_NAME(double, "double");
DMLC_DECLARE_TYPE_NAME(int, "int");
DMLC_DECLARE_TYPE_NAME(int64_t, "long");
DMLC_DECLARE_TYPE_NAME(uint32_t, "int (non-negative)");
DMLC_DECLARE_TYPE_NAME(uint64_t, "long (non-negative)");
DMLC_DECLARE_TYPE_NAME(std::string, "string");
DMLC_DECLARE_TYPE_NAME(bool, "boolean");
DMLC_DECLARE_TYPE_NAME(void*, "ptr");
 
template<typename Then, typename Else>
struct IfThenElseType<true, Then, Else> {
  typedef Then Type;
};
 
template<typename Then, typename Else>
struct IfThenElseType<false, Then, Else> {
  typedef Else Type;
};
}  // namespace dmlc
#endif  // DMLC_TYPE_TRAITS_H_