RWTValHashMultiSet<T,H,EQ,A>
Module: Essential Tools Module Group: STL Extension-based Collection Classes
Does not inherit
- Local Index
- Synopsis
- Description
- Persistence
- Example
- Related Classes
- Public Typedefs
- Public Constructors
- Public Member Operators
- Public Member Functions
- Related Global Operators
Local Index
Members
Non-Members
Synopsis
#include <rw/tvhasht.h> RWTValHashMultiSet<T,H,EQ,A>
Description
This class maintains a collection of values, which are stored according to a hash object of type H. H must offer a const hash function for elements of type T via public member
unsigned long operator()(const T& x) const;
Objects within the collection will be grouped together based on an equality object of type EQ. EQ must ensure this grouping via public member
bool operator()(const T& x, const T& y) const
which should return true if x and y are equivalent, false otherwise.
Note: Any two keys that are equivalent must hash to the same value.
RWTValHashMultiSet<T,H,EQ,A> may contain multiple items that are equivalent to each other. (RWTValHashSet<T,H,EQ,A> will not accept an item that is equivalent to an item already in the collection.)
The value type must have operator==() defined. This requirement is imposed by the C++ Standard Library.
Persistence
Isomorphic
Example
#include <iostream>
#include <functional>
#include <rw/tvhasht.h>
#include <rw/cstring.h>
struct simple_hash
{
unsigned long
operator()(const RWCString& ref) const {
size_t n = ref.length ();
return (unsigned long)(n ? n * size_t (ref [0]) : 0);
}
};
int main ()
{
RWTValHashMultiSet<RWCString,simple_hash,std::equal_to<RWCString> > set1;
RWTValHashMultiSet<RWCString,simple_hash,std::equal_to<RWCString> > set2;
set1.insert("one");
set1.insert("two");
set1.insert("three");
set1.insert("one"); // OK: duplicates allowed
set1.insert("one");
std::cout << set1.entries() << std::endl; // Prints "5"
set2.insert("one");
set2.insert("five");
set2.insert("one");
std::cout << ((set1.isEquivalent(set2)) ? "true" : "false") << std::endl;
// Prints "false"
set2.intersection(set1);
set1.clear();
std::cout << set1.entries() << std::endl; // Prints "0"
std::cout << set2.entries() << std::endl; // Prints "2"
return 0;
}
Program output:
5 false 0 2
Related Classes
Class RWTValHashSet<T,H,EQ,A> offers the same interface to a collection that will not accept multiple items that compare equal to each other.
Class rw_hashmultiset<T,H,EQ,A> is the C++-standard compliant collection that serves as the underlying implementation for RWTValHashMultiSet<T,H,EQ,A>.
Public Typedefs
typedef rw_hashmultiset<T,H,EQ,A> container_type; typedef typename container_type::iterator iterator; typedef typename container_type::const_iterator const_iterator; typedef typename container_type::size_type size_type; typedef T value_type; typedef T& reference; typedef const T& const_reference;
Public Constructors
RWTValHashMultiSet<T,H,EQ,A>(size_type sz = 1024,
const H& h = H(),const EQ& eq = EQ());
Constructs an empty set. The underlying hash table representation will have sz buckets, will use h as its hashing function and will use eq to determine equivalence between elements.
RWTValHashMultiSet<T,H,EQ,A> (const rw_hashmultiset<T,H,EQ,A>& s);
Constructs a set by copying all elements of s.
RWTValHashMultiSet<T,H,EQ,A> (const RWTValHashMultiSet<T,H,EQ,A>&);
Copy constructor.
RWTValHashMultiSet<T,H,EQ,A> (const H& h,size_type sz = RW_DEFAULT_CAPACITY);
Creates an empty hashed multi-set which uses the hash object h and has an initial hash table capacity of sz.
RWTValHashMultiSet<T,H,EQ,A>(const T* first, const T* last,size_type sz = 1024,const H& h = H(), const EQ& eq = EQ());
Constructs a set by copying elements from the array of Ts pointed to by first, up to, but not including, the element pointed to by last. The underlying hash table representation will have sz buckets, will use h as its hashing function and will use eq to determine equivalence between elements.
Public Member Operators
RWTValHashMultiSet<T,H,EQ,A>& operator=(const RWTValHashMultiSet<T,H,EQ,A>& s); RWTValHashMultiSet<T,H,EQ,A>& operator=(const rw_hashmultiset<T,H,EQ,A>& s);
Destroys all elements of self and replaces them by copying all elements of s.
bool operator==(const RWTValHashMultiSet<T,H,EQ,A>& s) const; bool operator==(const rw_hashmultiset<T,H,EQ,A>& s) const;
Returns true if self compares equal to s, otherwise returns false. Two collections are equal if both have the same number of entries, and iterating through both collections produces, in turn, individual elements that compare equal to each other.
Public Member Functions
void apply(void (*fn)(const_reference,void*), void* d) const;
Applies the user-defined function pointed to by fn to every item in the collection. This function must have prototype:
void yourfun(const_reference a, void* d);
Client data may be passed through parameter d.
iterator begin(); const_iterator begin() const;
Returns an iterator positioned at the first element of self.
size_type capacity() const;
Returns the number of buckets (slots) available in the underlying hash representation. See resize below.
void clear();
Clears the collection by removing all items from self. Each item will have its destructor called.
bool contains(const_reference a) const;
Returns true if there exists an element t in self that compares equal to a, otherwise returns false.
bool contains(bool (*fn)(const_reference,void*), void* d) const;
Returns true if there exists an element t in self such that the expression ((*fn)(t,d)) is true, otherwise returns false. fn points to a user-defined tester function which must have prototype:
bool yourTester(const_reference a, void* d);
Client data may be passed through parameter d.
void difference(const RWTValHashMultiSet<T,H,EQ,A>& s);
Sets self to the set-theoretic difference given by (self - s).
iterator end(); const_iterator end() const;
Returns an iterator positioned"just past" the last element in self.
size_type entries() const;
Returns the number of items in self.
float fillRatio() const;
Returns the ratio entries()/capacity().
bool find(const_reference a,T& k) const;
If there exists an element t in self such that the expression (t == a) is true, assigns t to k and returns true. Otherwise, returns false and leaves the value of k unchanged.
bool find(bool (*fn)(const_reference,void*),void* d,T& k) const;
If there exists an element t in self that compares equal to a, assigns t to k and returns true. Otherwise, returns false and leaves the value of k unchanged. fn points to a user-defined tester function which must have prototype:
bool yourTester(const_reference a, void* d);
Client data may be passed through parameter d.
bool insert(const_reference a);
Adds the item a to the collection. Returns true.
void intersection(const RWTValHashMultiSet<T,H,EQ,A>& s);
Destructively performs a set theoretic intersection of self and s, replacing the contents of self with the result.
bool isEmpty() const;
Returns true if there are no items in the collection, false otherwise.
bool isEquivalent(const RWTValHashMultiSet<T,H,EQ,A>& s) const;
Returns true if there is set equivalence between self and s, and returns false otherwise.
bool isProperSubsetOf(const RWTValHashMultiSet<T,H,EQ,A>& s) const;
Returns true if self is a proper subset of s, and returns false otherwise.
bool isSubsetOf(const RWTValHashMultiSet<T,H,EQ,A>& s) const;
Returns true if self is a subset of s, and returns false otherwise.
size_type occurrencesOf(const_reference a) const;
Returns the number of elements t in self that compares equal to a.
size_type
occurrencesOf(bool (*fn)(const_reference,void*),
void* d) const;
Returns the number of elements t in self such that the expression((*fn)(t,d)) is true. fn points to a user-defined tester function which must have prototype:
bool yourTester(const_reference a, void* d);
Client data may be passed through parameter d.
bool remove(const_reference a);
Removes the first element t in self that compares equal to a and returns true. Returns false if there is no such element.
bool remove(bool (*fn)(const_reference,void*), void* d);
Removes the first element t in self such that the expression ((*fn)(t,d)) is true and returns true. Returns false if there is no such element. fn points to a user-defined tester function which must have prototype:
bool yourTester(const_reference a, void* d);
Client data may be passed through parameter d.
size_type removeAll(const_reference a);
Removes all elements t in self that compare equal to a. Returns the number of items removed.
size_type removeAll(bool (*fn)(const_reference,void*), void* d);
Removes all elements t in self such that the expression ((*fn)(t,d))is true. Returns the number of items removed. fn points to a user-defined tester function which must have prototype:
bool yourTester(const_reference a, void* d);
Client data may be passed through parameter d.
void resize(size_type sz);
Changes the capacity of self by creating a new hashed multi-set with a capacity of sz. resize copies every element of self into the new container and finally swaps the internal representation of the new container with the internal representation of self.
rw_hashmultiset<T,H,EQ,A>& std(); const rw_hashmultiset<T,H,EQ,A>& std() const;
Returns a reference to the underlying collection that serves as the implementation for self. This reference may be used freely, providing access to the C++-standard interface as well as interoperability with other software components that make use of the C++-standard collections.
void symmetricDifference(const RWTValHashMultiSet<T,H,EQ,A>& s);
Destructively performs a set theoretic symmetric difference operation on self and s. Self is replaced by the result. A symmetric difference can be informally defined as 
.
void Union(const RWTValHashMultiSet<T,H,EQ,A>& rhs);
Destructively performs a set theoretic union operation on self and rhs. Self is replaced by the result. Note the uppercase"U" in Union to avoid conflict with the C++ reserved word.
Related Global Operators
RWvostream&
operator<<(RWvostream& strm,
const RWTValHashMultiSet<T,H,EQ,A>& coll);
RWFile&
operator<<(RWFile& strm,
const RWTValHashMultiSet<T,H,EQ,A>& coll);
Saves the collection coll onto the output stream strm, or a reference to it if it has already been saved.
RWvistream&
operator>>(RWvistream& strm,
RWTValHashMultiSet<T,H,EQ,A>& coll);
RWFile&
operator>>(RWFile& strm, RWTValHashMultiSet<T,H,EQ,A>& coll);
Restores the contents of the collection coll from the input stream strm.
RWvistream&
operator>>(RWvistream& strm,
RWTValHashMultiSet<T,H,EQ,A>*& p);
RWFile&
operator>>(RWFile& strm, RWTValHashMultiSet<T,H,EQ,A>*& p);
Looks at the next object on the input stream strm and either creates a new collection off the heap and sets p to point to it, or sets p to point to a previously read instance. If a collection is created off the heap, then you are responsible for deleting it.
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