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Better version of the built in array hash function.

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[SVN r28089]
This commit is contained in:
Daniel James
2005-04-10 20:07:50 +00:00
parent 18b3a53699
commit 8b08528611
1 changed files with 25 additions and 36 deletions
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61
include/boost/functional/hash/hash.hpp
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@@ -38,7 +38,17 @@ namespace boost
std::size_t hash_value(long); std::size_t hash_value(long);
std::size_t hash_value(unsigned long); std::size_t hash_value(unsigned long);
// Hopefully, I'll be able to remove this workaround soon.
#if BOOST_WORKAROUND(__GNUC__, == 4)
template <class T> std::size_t hash_value(T*); template <class T> std::size_t hash_value(T*);
#else
template <class T> std::size_t hash_value(T* const&);
#endif
#if !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
template< class T, unsigned N >
std::size_t hash_value(const T (&array)[N]);
#endif
std::size_t hash_value(float v); std::size_t hash_value(float v);
std::size_t hash_value(double v); std::size_t hash_value(double v);
@@ -87,7 +97,11 @@ namespace boost
} }
// Implementation by Alberto Barbati and Dave Harris. // Implementation by Alberto Barbati and Dave Harris.
template <class T> inline std::size_t hash_value(T* v) #if BOOST_WORKAROUND(__GNUC__, == 4)
template <class T> std::size_t hash_value(T* v)
#else
template <class T> std::size_t hash_value(T* const& v)
#endif
{ {
std::size_t x = static_cast<std::size_t>( std::size_t x = static_cast<std::size_t>(
reinterpret_cast<std::ptrdiff_t>(v)); reinterpret_cast<std::ptrdiff_t>(v));
@@ -96,7 +110,7 @@ namespace boost
namespace hash_detail namespace hash_detail
{ {
#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) #if !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
// This allows boost::hash to be specialised for classes in the // This allows boost::hash to be specialised for classes in the
// standard namespace. It appears that a strict two phase template // standard namespace. It appears that a strict two phase template
// implementation only finds overloads that are in the current // implementation only finds overloads that are in the current
@@ -112,27 +126,7 @@ namespace boost
return hash_value(v); return hash_value(v);
} }
}; };
#else // BOOST_NO_FUNCTION_TEMPLATE_ORDERING
template <class T, std::size_t Size>
struct call_hash<T[Size]>
{
static std::size_t call(T const* val)
{
return boost::hash_range(val, val + Size);
}
};
#if !defined(__BORLANDC__)
template <class T>
struct call_hash<T[0u]>
{
static std::size_t call(T const*)
{
return 0;
}
};
#endif
#else // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
template <bool IsArray> template <bool IsArray>
struct call_hash_impl struct call_hash_impl
{ {
@@ -202,6 +196,14 @@ namespace boost
} }
} }
#if !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
template< class T, unsigned N >
inline std::size_t hash_value(const T (&array)[N])
{
return hash_range(array, array+N);
}
#endif
#if BOOST_WORKAROUND(__GNUC__, < 3) && !defined(__SGI_STL_PORT) && !defined(_STLPORT_VERSION) #if BOOST_WORKAROUND(__GNUC__, < 3) && !defined(__SGI_STL_PORT) && !defined(_STLPORT_VERSION)
template <class Ch, class A> template <class Ch, class A>
inline std::size_t hash_value(std::basic_string<Ch, std::string_char_traits<Ch>, A> const& v) inline std::size_t hash_value(std::basic_string<Ch, std::string_char_traits<Ch>, A> const& v)
@@ -267,19 +269,6 @@ namespace boost
return hash_detail::call_hash<T>::call(val); return hash_detail::call_hash<T>::call(val);
} }
}; };
#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \
&& !defined(__BORLANDC__)
template <class T> struct hash<T[0]>
: std::unary_function<T[0], std::size_t>
{
std::size_t operator()(T const*) const
{
return 0;
}
};
#endif
} }
#endif #endif