hash_map
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An associative container that
manages a set of ordered key/value pairs. The pairs are ordered by key, based on
a user-supplied hash function. Only one value can be associated with a
particular key. You can quickly find this value due to the hash_map
's underlying data structure.
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/hashmap.h>
template
<
class Key,
class Value,
class Hash,
class Equal,
class Allocator
>
class hash_map
Interface
Constructor
explicit
hash_map( size_t n ,
const Hash& hash ,
const Equal& equal ,
float load_ratio ,
const Allocator& alloc )
Constructs an empty map,
with n (default 203 )
initial table entries, that orders its keys 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_map(
const_iterator first ,
const_iterator last ,
size_t n ,
const Hash& hash ,
const Equal& equal ,
float load_ratio ,
const Allocator& alloc )
Constructs a map that
contains copies of the key/value pairs in the range
[ first ,
last ) .
Constructor
hash_map(
const hash_map< Key, Value, Hash, Equal, Allocator >& other
)
Constructs a copy of other
.
Destructor
~hash_map()
Destroys the map and
erases all of its key/value pairs.
=
hash_map<
Key, Value, Hash, Equal, Allocator >& operator=( const hash_map<
Key, Value, Hash, Equal, Allocator >& other
)
Replaces the map's
contents with other .
[]
Value&
operator []( const Key& key )
If no value is associated
with key , associates key
with a default-constructed value and returns a reference to this new value.
Otherwise, returns a reference to the value already associated with key
.
begin
iterator
begin()
Returns an iterator
positioned at map's first key/value pair.
begin
const_iterator
begin() const
Returns an iterator
positioned at map's first key/value pair.
bucket_count
size_type
bucket_count() const
Returns the number of
buckets the map contains.
clear
void
clear()
Erases all of map's
key/value pairs.
count
size_type
count( const Key& key )
const
Returns the number of
key/value pairs map contains with a key that matches key
.
empty
bool
empty() const
Returns true
if map contains no entries.
end
iterator
end()
Returns an iterator
positioned immediately after map's last key/value pair.
end
const_iterator
end() const
Returns an iterator
positioned immediately after map's last key/value pair.
erase
void
erase( iterator pos )
Erases the key/value pair
at pos .
erase
void
erase( iterator first ,
iterator last )
Erases the key/value
pairs in range [ first
, last )
.
erase
size_type
erase( const Key& key )
Erases all key/value
pairs with a key that matches key and returns the
number of elements erased.
find
iterator
find( const Key& key )
If map contains a
key/value pair with a key that matches key ,
returns an iterator positioned at the matching pair. Otherwise, returns an
iterator positioned at end() .
find
const_iterator
find( const Key& key )
const
If map contains a
key/value pair with a key that matches key ,
returns a constant iterator positioned at the matching pair. Otherwise,
returns a constant iterator positioned at end()
.
get_allocator
Allocator
get_allocator() const
Returns a copy of the
allocator that map 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 value_type& pair
)
If map does not contain a
key/value pair with a key that matches that of pair
, inserts a copy of pair and returns a pair with a
first element that is an iterator positioned at the new key/value pair and a
second element that is true . If map already
contains a key/value pair with a key that matches that of pair
, returns a pair with a first element that is an iterator positioned at the
existing key/value pair and a second element that is false
.
insert
void
insert( const value_type* first ,
const value_type*
last )
Inserts copies of the
key/value pairs in the range [ first
, last ) .
insert
void
insert( const_iterator first ,
const_iterator last )
Inserts copies of the
key/value pairs in the range [ first
, last ) .
key_eq
Equal
key_eq() const
Returns the comparison
object used to compare map's keys.
max_size
size_type
max_size() const
Returns the maximum
number of key/value pairs that map can contain.
resize
void
resize( size_t n )
Resizes the map to have
at least n number of hash buckets.
size
size_type
size() const
Returns the number of
key/value pairs that map contains.
swap
void
swap( hash_map< Key, Value, Hash, Equal, Allocator >& other
)
Exchanges the contents of
map and other .
Non-Member Functions
==
bool
operator==( const hash_map< Key, Value, Equal, Allocator >& x
, const hash_map< Key, Value,
Equal, Allocator >& y )
const
Returns true
if x contains the same items in the same order as y
.
<
bool
operator<( const hash_map< Key, Value, Equal, Allocator >& x
, const hash_map< Key, Value,
Equal, Allocator >& y )
const
Returns true
if x is lexicographically less than y.
swap
void
swap( hash_map< Key, Value, Equal, Allocator >& x
, hash_map< Key, Value, Equal,
Allocator >& y ) const
Exchanges the contents of
x and y .
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