libcruft-util/types.hpp
Danny Robson 4891c6af0e Add sign_cast functions
These safely cast between signed and unsigned numeric quantities,
aborting if the result cannot be safely converted (as opposed to size
expanding or throwing).
2011-06-15 22:38:58 +10:00

97 lines
1.9 KiB
C++

#ifndef __TYPES_HPP
#define __TYPES_HPP
#include <cstdint>
#include <string>
#include <limits>
template <int BITS>
struct bits_type;
template <> struct bits_type< 8> {
static const bool has_floating = false;
typedef uint8_t uint;
typedef int8_t sint;
typedef uint8_t floating;
};
template <> struct bits_type<16> {
static const bool has_floating = false;
typedef uint16_t uint;
typedef int16_t sint;
typedef uint16_t floating;
};
template <> struct bits_type<32> {
static const bool has_floating = true;
typedef uint32_t uint;
typedef int32_t sint;
typedef float floating;
};
template <> struct bits_type<64> {
static const bool has_floating = true;
typedef uint64_t uint;
typedef int64_t sint;
typedef double floating;
};
template <typename T>
struct sized_type : public bits_type<sizeof(T) * 8>
{ };
template <typename T>
std::string type_to_string (void);
template <typename T>
struct sign_types;
template <> struct sign_types <signed int> {
typedef signed int with_sign;
typedef unsigned int without_sign;
};
template <> struct sign_types <unsigned int> {
typedef signed int with_sign;
typedef unsigned int without_sign;
};
/// Safely cast a numeric type to its signed comparison, aborting if the
/// result is not representable.
template <typename T>
typename sign_types<T>::with_sign
sign_cast (const typename sign_types<T>::without_sign v)
{
check_hard (v <= std::numeric_limits<typename sign_types<T>::without_sign>::max () >> 1);
return static_cast <typename sign_types<T>::with_sign> (v);
}
/// Safely cast a numeric type to its unsigned comparison, aborting if the
/// result is not representable.
template <typename T>
typename sign_types<T>::without_sign
sign_cast (const typename sign_types<T>::with_sign v)
{
check_hard (v >= 0);
return static_cast <typename sign_types<T>::without_sign> (v);
}
#endif // __TYPES_HPP