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Namerw_hashmultimap - Rogue Wave library class
Synopsis
#include <rw/rwstl/hashmmap.h>
rw_hashmultimap<K,V,Hash,EQ> mmap;
Description
Class rw_hashmultimap<K,V,Hash,EQ> maintains a collection of mappings
between K and V, implemented as a hash table of pair<const K,V> in which
there may be many pairs with the same K instance. Since this is a value
based collection, objects are copied into and out of the collection. As
with all classes that meet the ANSI associative container specification,
rw_hashmap provides for iterators that reference its elements.
Operations that alter the contents of rw_hashmap may invalidate other
iterators that reference the container. Since the contents of rw_hashmap
are in pseudo-random order, the only iterator ranges that will usually
make sense are the results of calling equal_range(key), and the entire
range from begin() to end().
Persistence
None
Public Typedefs
typedef K key_type;
typedef Hash key_hash;
typedef EQ key_equal;
typedef pair<K,V> value_type; // or ... "const K"
typedef (unsigned) size_type; //from rw_slist
typedef (int) difference_type; // from rw_slist
typedef (value_type&) reference;
typedef (const value_type&) const_reference; //from rw_slist
Iterators over rw_hashmultimap<K,V,Hash,EQ> are forward iterators.
typedef (scoped Iterator) iterator;
typedef (scoped ConsIterator) const_iterator;
Public Constructors
rw_hashmultimap<K,V,Hash,EQ>(size_type sz = 1024,
const Hash& h = Hash(),
const EQ& eq = EQ());
Construct an empty rw_hashmultimap<K,V,Hash,EQ> with sz slots, using h as
the hash object, and eq as the equality comparator.
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rw_hashmultimap<K,V,Hash,EQ>(const
rw_hashmultimap<K,V,Hash,EQ>& mmap);
Construct an rw_hashmultimap<K,V,Hash,EQ> which is a copy of mmap. Each
element from mmap will be copied into self.
rw_hashmultimap<K,V,Hash,EQ>(const_iterator first,
const_iterator bound
size_type sz=1024,
const Hash& h = Hash(),
const EQ& eq = EQ());
Construct an rw_hashmultimap<K,V,Hash,EQ> with sz slots, using h as the
hash object, and eq as the equality comparator, containing a copy of each
pair referenced by the range starting with first and bounded by bound.
rw_hashmultimap<K,V,Hash,EQ>(const value_type* first,
const value_type* bound
size_type sz=1024,
const Hash& h = Hash(),
const EQ& eq = EQ());
Construct an rw_hashmultimap<K,V,Hash,EQ> with sz slots, using h as the
hash object, and eq as the equality comparator, containing a copy of each
pair referenced by the range starting with first and bounded by bound.
Public Destructor
~rw_hashmultimap<K,V,Hash,EQ>();
The destructor releases the memory used by the container's
implementation.
Public Operators
rw_hashmultimap<K,V,Hash,EQ>&
operator=(const rw_hashmultimap<K,V,Hash,EQ>& rhs);
Sets self to have the same capacity, Hash and EQ as rhs, removes all
self's current contents, and replaces them with copies of the elements in
rhs.
bool
operator==(const rw_hashmultimap<K,V,Hash,EQ> & rhs) const;
Returns true if self and rhs have the same number of elements, and for
each value_type in self, there is exactly one corresponding value_type in
rhs that has a first part for which the EQ object in self returns true,
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and a second part for which operator==() returns true. The need to test
both parts, and ensure that the matches are one-to-one means that this
operator may be significantly slower than the method equal_by_keys()
described below.
Accessors
iterator
begin();
The iterator returned references the first item in self. If self is
empty, the iterator is equal to end(). Note that because items are
stored in pseudo-random order, this iterator might reference any item
that has been stored in self.
const_iterator
begin() const;
The iterator returned references the first item in self. If self is
empty, the iterator is equal to end(). Note that because items are
stored in pseudo-random order, this iterator might reference any item
that has been stored in self.
iterator
end();
The iterator returned marks the location "off the end" of self. It may
not be dereferenced.
const_iterator
end() const;
The iterator returned marks the location "off the end" of self. It may
not be dereferenced.
pair<const_iterator, const_iterator>
equal_range(const key_type key) const;
Returns pair<const_iterator,const_iterator>(lower_bound(key),
upper_bound(key)). Upper and lower bound have special meaning for hash-
based collections. See discussion elsewhere.
pair<iterator, iterator>
equal_range(const key_type key);
Returns pair<iterator,iterator>(lower_bound(key), upper_bound(key)).
Upper and lower bound have special meaning for hash-based collections.
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See discussion elsewhere.
const_iterator
lower_bound(const key_type& key) const;
Returns the lower bound of key in self. This has a special meaning for
hash-based collections. See discussion elsewhere.
iterator
lower_bound(const key_type& key);
Returns the lower bound of key in self. This has a special meaning for
hash-based collections. See discussion elsewhere.
const_iterator
upper_bound(const key_type& key) const;
Returns the upper bound of key in self. This has a special meaning for
hash-based collections. See discussion elsewhere.
iterator
upper_bound(const key_type& key);
Returns the upper bound of key in self. This has a special meaning for
hash-based collections. See discussion elsewhere.
Const Public Member Functions
size_type
capacity() const;
Returns the number of slots in the hash table that self uses.
bool
empty() const;
Returns true if self is empty.
float
fill_ratio() const;
Returns the result of calculating size()/capacity().
size_type
size() const;
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Returns the number of items currently held in self.
Mutators
void
clear();
A synonym for erase(begin(),end());
size_type
erase(const key_type& key);
Removes all pairs in self for which the first part is EQ to key, and
returns the number of removed elements.
iterator
erase(iterator iter);
Removes the element referenced by iter and returns an iterator
referencing the "next" element. If iter does not reference an item in
self, the result is undefined.
iterator
erase(iterator first, iterator bound);
Removes each element in the range which begins with first and is bound by
bound. Returns an iterator referencing bound. If first does not
reference an item in self (and if first and bound are not equal), the
effect is undefined.
pair<iterator,bool>
insert(const value_type& val);
Inserts the pair, val, and returns a pair with an iterator referencing
the new element and true.
size_type
insert(iterator ignore, const value_type& val);
Inserts the pair, val, returning 1. Note that the first argument is
provided only for conformance with the ANSI associative container
specification, and is ignored by the method, since hash table look up can
be done in constant time.
size_type
insert(const value_type* first, const value_type* bound);
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For each element in the range beginning with first and bounded by bound,
the element is copied into self. Returns the number of elements
inserted.
size_type
insert(const_iterator first, const_iterator bound);
For each element in the range beginning with first and bounded by bound,
the element is copied into self. Returns the number of elements
inserted.
void
swap(rw_hashmultimap<K,V,Hash,EQ>& other);
Exchanges the contents of self with other including the Hash and EQ
objects. This method does not copy or destroy any of the items exchanged
but exchanges the underlying hash tables.
Special Methods for Multimaps
size_type
count(const key_type& key) const;
Returns the number of pairs in self which have key EQ to their first
element.
bool
equal_by_keys(const rw_hashmultimap<K,V,Hash,EQ>& rhs) const;
Returns true if self and rhs have the same size, and if for each distinct
key_type in self, self and rhs have the same number of pairs with first
parts that test EQ to that instance. Note that this method does not
compare the V (second) part of the pair of the items, so it will run
slightly faster than operator==().
const_iterator
find(const key_type& key) const;
Returns a const_iterator referencing some pair with key as its first
element, if such a pair is contained in self, else returns end().
iterator
find(const key_type& key);
Returns an iterator referencing some pair with key as its first element,
if such a pair is contained in self, else returns end().
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void
resize(size_type sz);
Resizes self's hash table to have sz slots; and re-hashes all self's
elements into the new table. Can be very expensive if self holds many
elements.
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