For the full specification, see section 6.3 of the
C++ Standard Library Technical Report
and issue 6.18 of the
Library Extension Technical Report Issues List (page 63).
Defines boost::hash,
and helper functions.
std::unary_function<T, std::size_t>
A TR1 compliant hash function object.
std::size_t
T const&
hash_value(val)
The call to hash_value
is unqualified, so that custom overloads can be
found via argument dependent lookup.
This is not defined when the macro BOOST_HASH_NO_EXTENSIONS
is defined. The specializations are still defined, so only the specializations
required by TR1 are defined.
Forward declared in
<boost/functional/hash_fwd.hpp>
This hash function is not intended for general use, and isn't
guaranteed to be equal during separate runs of a program - so
please don't use it for any persistent storage or communication.
Only throws if
hash_value(T) throws.
bool
std::size_t
bool
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
char
std::size_t
char
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
signed char
std::size_t
signed char
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
unsigned char
std::size_t
unsigned char
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
wchar_t
std::size_t
wchar_t
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
short
std::size_t
short
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
unsigned short
std::size_t
unsigned short
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
int
std::size_t
int
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
unsigned int
std::size_t
unsigned int
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
long
std::size_t
long
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
unsigned long
std::size_t
unsigned long
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
long long
std::size_t
long long
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
unsigned long long
std::size_t
unsigned long long
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
float
std::size_t
float
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
double
std::size_t
double
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
long double
std::size_t
long double
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
std::string
std::size_t
std::string const&
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
std::wstring
std::size_t
std::wstring const&
Unspecified in TR1, except that equal arguments yield the same result.
hash_value(val) in Boost.
Doesn't throw
T*
std::size_t
T*
Unspecified in TR1, except that equal arguments yield the same result.
Doesn't throw
std::type_index
std::size_t
std::type_index
val.hash_code()
Doesn't throw
Only available if it's in your standard library and Boost.Config
is aware of it.
void
size_t &
T const&
Called repeatedly to incrementally create a hash value from
several variables.
Updates seed with a new hash value generated by
combining it with the result of
hash_value(v). Will
always produce the same result for the same combination of
seed and
hash_value(v) during
the single run of a program.
hash_value is called without
qualification, so that overloads can be found via ADL.
This is an extension to TR1
Forward declared in
<boost/functional/hash_fwd.hpp>
This hash function is not intended for general use, and isn't
guaranteed to be equal during separate runs of a program - so
please don't use it for any persistent storage or communication.
Only throws if hash_value(T) throws.
Strong exception safety, as long as hash_value(T)
also has strong exception safety.
std::size_t
It
It
void
std::size_t&
It
It
Calculate the combined hash value of the elements of an iterator
range.
For the two argument overload:
size_t seed = 0;
for(; first != last; ++first)
{
hash_combine(seed, *first);
}
return seed;
For the three arguments overload:
for(; first != last; ++first)
{
hash_combine(seed, *first);
}
hash_range is sensitive to the order of the elements
so it wouldn't be appropriate to use this with an unordered
container.
This is an extension to TR1
Forward declared in
<boost/functional/hash_fwd.hpp>
This hash function is not intended for general use, and isn't
guaranteed to be equal during separate runs of a program - so
please don't use it for any persistent storage or communication.
Only throws if hash_value(std::iterator_traits<It>::value_type)
throws. hash_range(std::size_t&, It, It) has basic exception safety as long as
hash_value(std::iterator_traits<It>::value_type)
has basic exception safety.
Implementation of the hash function.
std::size_t
bool
std::size_t
char
std::size_t
signed char
std::size_t
unsigned char
std::size_t
wchar_t
std::size_t
short
std::size_t
unsigned short
std::size_t
int
std::size_t
unsigned int
std::size_t
long
std::size_t
unsigned long
std::size_t
long long
std::size_t
unsigned long long
std::size_t
float
std::size_t
double
std::size_t
long double
std::size_t
T* const&
unsigned
std::size_t
T (&val)[N]
unsigned
std::size_t
const T (&val)[N]
std::size_t
std::basic_string<Ch, std::char_traits<Ch>, A> const&
std::size_t
std::pair<A, B> const&
std::size_t
std::vector<T, A> const&
std::size_t
std::list<T, A> const&
std::size_t
std::deque<T, A> const&
std::size_t
std::set<K, C, A> const&
std::size_t
std::multiset<K, C, A> const&
std::size_t
std::map<K, T, C, A> const&
std::size_t
std::multimap<K, T, C, A> const&
std::size_t
std::complex<T> const&
std::size_t
std::type_index
std::size_t
std::size_t
std::array<T, N> const&
std::size_t
std::tuple<T...>
Generally shouldn't be called directly by users, instead they should use
boost::hash, boost::hash_range
or boost::hash_combine which
call hash_value without namespace qualification so that overloads
for custom types are found via ADL.
This is an extension to TR1
This hash function is not intended for general use, and isn't
guaranteed to be equal during separate runs of a program - so
please don't use it for any persistent storage or communication.
Only throws if a user supplied version of
hash_value
throws for an element of a container, or
one of the types stored in a pair.
Types
Returns
bool,
char, signed char, unsigned char, wchar_t,
short, unsigned short,
int, unsigned int, long, unsigned long
val
long long, unsigned long long
val when abs(val) <= std::numeric_limits<std::size_t>::max().
float, double, long double
An unspecified value, except that equal arguments shall yield the same result.
T*
An unspecified value, except that equal arguments shall yield the same result.
T val[N],
const T val[N]
hash_range(val, val+N)
std:basic_string<Ch, std::char_traits<Ch>, A>,
std::vector<T, A>,
std::list<T, A>,
std::deque<T, A>,
std::set<K, C, A>,
std::multiset<K, C, A>,
std::map<K, T, C, A>,
std::multimap<K, T, C, A>,
std::array<T, N>
hash_range(val.begin(), val.end())
std::pair<A, B>
size_t seed = 0;
hash_combine(seed, val.first);
hash_combine(seed, val.second);
return seed;
std::tuple<T...>
size_t seed = 0;
hash_combine(seed, get<0>(val));
hash_combine(seed, get<1>(val));
// ....
return seed;
std::complex<T>
When T is a built in type and val.imag() == 0, the result is equal to hash_value(val.real()). Otherwise an unspecified value, except that equal arguments shall yield the same result.
std::type_index
val.hash_code()