hash_set

A container that is optimized for fast associative lookup. Items are matched using the user-supplied Equal comparator. When an item is inserted into a hash_set , it is stored in a data structure that allows the item to be found quickly. Within the data structure, the items are ordered according to a user-defined Hash function object. Unlike a hash_multiset , a hash_set cannot contain multiple copies of the same item.

Hash containers are only a proposed addition to the ANSI/ISO Standard Template Library, and have not been accepted for inclusion in the final specification. We have included hash containers in Standards<ToolKit> to provide you with the latest STL technology available.

Library

Standards<ToolKit>

Declaration


#include <ospace/osstd/hashset.h>

template< class T, class Hash, class Equal, class Allocator >
class hash_set

Interface

Constructor
explicit hash_set( size_t n , const Hash& hash , const Equal& equal , float load_ratio , const Allocator& alloc )
Constructs an empty set, with n (default 203 ) initial table entries, that orders its elements using the hash function (default Hash() ), key comparison function equal (default Equal() ), and allocator alloc (default Allocator() ). The load_ratio value (default 0.75 ) is used to tune the internal hash table.
Constructor
hash_set( const_iterator first , const_iterator last , size_t n , const Hash& hash , const Equal& equal , float load_ratio , const Allocator& alloc )
Constructs a set that contains copies of elements in the range [ first , last ) .
Constructor
hash_set( const hash_set< T, Hash, Equal, Allocator >& other )
Constructs a set that is a copy of other .
Destructor
~hash_set()
Destroys the set and erases all of its items.
=
hash_set< T, Hash, Equal, Allocator >& operator=( const hash_set< T, Hash, Equal, Allocator >& other )
Replaces the set's contents with a copy of other 's.
begin
iterator begin()
Returns an iterator positioned at the first element in the set.
begin
const_iterator begin() const
Returns a constant iterator positioned at the first element in the set.
bucket_count
size_type bucket_count() const
Returns the number of hash buckets that this set contains.
clear
void clear()
Erases all of the set elements.
count
size_type count( const T& value ) const
Returns the number of elements in the set that match value .
empty
bool empty() const
Returns true if the set contains no elements.
end
iterator end()
Returns an iterator positioned immediately after the last item in the set.
end
const_iterator end() const
Returns a constant iterator positioned immediately after the last item in the set.
erase
void erase( iterator pos )
Erases the element at pos .
erase
void erase( iterator first , iterator last )
Erases the elements in range [ first , last ) .
erase
size_type erase( const T& value )
Erases all elements that match value and returns the number of elements erased.
find
iterator find( const T& value )
If the set contains an element that matches value , returns an iterator positioned at the matching element. Otherwise, returns an iterator positioned at end() .
find
const_iterator find( const T& value ) const
If the set contains an element that matches value , returns a constant iterator positioned at the matching element. Otherwise, returns a constant iterator positioned at end() .
get_allocator
Allocator get_allocator() const
Returns a copy of the allocator the set is using to manage storage.
hash_funct
Hash hash_funct() const
Returns a copy of the hash function that map is using to order elements.
insert
pair< iterator, bool > insert( const T& value )
If the set does not contain an element that matches value , inserts a copy of value and returns a pair with a first element that is an iterator positioned at the new element and with a second element that is true . If the set already contains an element that matches value , returns a pair with a first element that is an iterator positioned at the existing element and with a second element that is false .
insert
iterator insert( iterator pos , const T& value )
Inserts a copy of value if the set does not a contain an element that matches value , using pos as a hint on where to start searching for the correct place to insert.
insert
void insert( const T* first , const T* last )
Inserts copies of elements in the range [ first , last ) .
insert
void insert( const_iterator first , const_iterator last )
Inserts copies of elements in the range [ first , last ) .
key_eq
Equal key_eq() const
Returns the set's key comparison object.
max_size
size_type max_size() const
Returns the maximum number of entries the set can contain.
resize
void resize( size_type n )
Resizes this set to contain at least n hash buckets.
size
size_type size() const
Returns the number of entries the set contains.
swap
void swap( hash_set< T, Hash, Equal, Allocator >& other )
Exchanges the contents of set and other .

Non-Member Functions

==
bool operator==( const hash_set< T, Hash, Equal, Allocator >& x , const hash_set< T, Hash, Equal, Allocator >& y )
Returns true if x contains the same items in the same order as y .
<
bool operator<( const hash_set< T, Hash, Equal, Allocator >& x , const hash_set< T, Hash, Equal, Allocator >& y )
Returns true if x is lexicographically less than y .
swap
void swap( hash_set< T, Hash, Equal, Allocator >& x , hash_set< T, Hash, Equal, Allocator >& y )
Exchanges the contents of x and y .

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