nerdcruft/libcruft-util
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Initial trunc_cast implementation

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This commit is contained in:
Danny Robson 2011-07-05 23:19:00 +10:00
parent be643f96d7
commit bc30b7c197
1 changed files with 34 additions and 7 deletions
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41
types.hpp
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@ -59,9 +59,9 @@ std::string type_to_string (void);
namespace detail {
template <typename T, typename V>
T
_sign_cast (typename enable_if<sizeof(T) == sizeof(V) &&
std::is_unsigned<T>::value &&
std::is_signed<V>::value, V>::type v)
_sign_cast (const typename enable_if<sizeof(T) == sizeof(V) &&
std::is_unsigned<T>::value &&
std::is_signed<V>::value, V>::type v)
{
check_hard (v >= 0);
return static_cast<T> (v);
@ -70,9 +70,9 @@ namespace detail {
template <typename T, typename V>
T
_sign_cast (typename enable_if<sizeof(T) == sizeof(V) &&
std::is_signed<T>::value &&
std::is_unsigned<V>::value, V>::type v)
_sign_cast (const typename enable_if<sizeof(T) == sizeof(V) &&
std::is_signed<T>::value &&
std::is_unsigned<V>::value, V>::type v)
{
check_hard (v < std::numeric_limits<V>::max () / 2);
return static_cast<T> (v);
@ -84,10 +84,37 @@ namespace detail {
/// NDEBUG is defined.
template <typename T, typename V>
T
sign_cast (V v)
sign_cast (const V v)
{ return detail::_sign_cast<T,V>(v); }
namespace detail {
// Same sign, no possibility of truncation with larger target type
template <typename T, typename V>
T
_trunc_cast (const typename enable_if<sizeof (T) >= sizeof (V) &&
std::is_signed<T>::value == std::is_signed<V>::value, V>::type v)
{ return v; }
template <typename T, typename V>
T
_trunc_cast (const typename enable_if<sizeof (T) < sizeof (V) &&
std::is_signed<T>::value == std::is_signed<V>::value, V>::type v) {
check_hard (v <= std::numeric_limits<T>::max ());
checK_hard (v >= std::numeric_limits<T>::min ());
return static_cast<T> (v);
}
}
template <typename T, typename V>
T
trunc_cast (V v)
{ return detail::_trunc_cast<T, V> (v); }
/// Returns the number of elements of a statically allocated array
template <typename T, size_t N>
size_t elems(T (&)[N])