RWTValHashMultiMap<K,T,H,EQ,A>

Module:  Essential Tools Module   Group:  STL Extension-based Collection Classes

Does not inherit

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Members

apply() begin() capacity() clear() const_iterator const_reference container_type contains()

end() entries() fillRatio() find() findKeyValue() findValue() insert() isEmpty()

iterator maxElement() minElement() occurrencesOf() operator=() operator==() reference remove()

removeAll() resize() RWTValHashMultiMap<K,T,H,EQ,A>() size_type std() value_type

Non-Members

operator>>()

operator<<()

#include <rw/tvhmmap.h> 
RWTValHashMultiMap<K,T,H,EQ,A> m;

This class maintains a collection of keys, each with an associated item of type T. These pairs are stored according to a hash object of type H. H must provide a const hash function on elements of type K via public member

unsigned long operator()(const K& x) const;

Equivalent keys 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 K& x, const K& y) const;

which should return true if x and y are equivalent.

Note: Any two keys that are equivalent must hash to the same value.

RWTValHashMultiMap<K,T,H,EQ,A> may contain multiple keys that are equivalent to each other. (RWTValHashMap<K,T,H,EQ,A> will not accept a key that is equivalent to any key already in the collection.) Equality is based on the comparison object and not on the == operator.

The value type must have operator==() defined. This requirement is imposed by the C++ Standard Library.

Isomorphic.

//
// tvhmmrat.cpp
//
#include <iostream>
#include <functional>

#include <rw/tvhmmap.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 ()
{
    RWCString trd = "Third";
    RWTValHashMultiMap <RWCString, int, simple_hash, std::equal_to<RWCString> >
        contest;

    contest.insert("First", 7);
    contest.insert(trd,3);
    contest.insert(trd,6);      // this contains two distinct values
                                // equivalent to trd 
    contest.insert("Second",2);
    contest.resize(8);

    std::cout << contest.capacity()  << "\n" 
              << contest.entries()   << "\n";
    std::cout << contest.fillRatio() << "\n";

    std::cout << "The table is " 
              << contest.fillRatio () * 100.0F << "% full\n";

    return 0;
}

Program Output:

The table is 50% full

Class RWTValHashMap<K,T,H,EQ,A> offers the same interface to a collection that will not accept multiple keys that compare equal to each other.

Class rw_hashmultimap<K,T,H,EQ,A> is the C++-standard collection that serves as the underlying implementation for this collection.

typedef rw_hashmultimap<K,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 std::pair <const K,T> value_type; 
typedef std::pair <const K,T>& reference; 
typedef const pair<const K,T>& const_reference; 

RWTValHashMultiMap<K,T,H,EQ,A>();

Constructs an empty map.

RWTValHashMultiMap<K,T,H,EQ,A>
  (const rw_hashmultimap<K,T,H,EQ,A>& m);

Constructs a map by copying all elements of m.

RWTValHashMultiMap<K,T,H,EQ,A>
  (const RWTValHashMultiMap<K,T,H,EQ,A>& rwm);

Copy constructor.

RWTValHashMultiMap<K,T,H,EQ,A>
  (const value_type* first, const value_type* last);

Constructs a map by copying elements from the array of association pairs pointed to by first, up to, but not including, the association pointed to by last.

RWTValHashMultiMap<K,T,H,EQ,A>&
operator=(const RWTValHashMultiMap<K,T,H,EQ,A>& m); 
RWTValHashMultiMap<K,T,H,EQ,A>&
operator=(const rw_hashmultimap<K,T,H,EQ,A>& m);

Destroys all elements of self and replaces them by copying all associations from m.

bool
operator==(const RWTValHashMultiMap<K,T,H,EQ,A>& m) const; 
bool
operator==(const rw_hashmultimap<K,T,H,EQ,A>& m) const;

Returns true if self compares equal to m, otherwise returns false. Two collections are equal if both have the same number of entries, and iterating through both collections produces, in turn, individual keys that compare equal to each other.

void
apply(void (*fn)(const K&, T&, void*),void* d); 
void
apply(void (*fn)(const K&,const T&, void*), void* d) const;

Applies the user-defined function pointed to by fn to every association in the collection. This function must have one of the prototypes:

void yourfun(const K&, T& a, void* d); 
void yourfun(const K&, const T& a,void* d); 

Client data may be passed through parameter d.

iterator
begin();
const_iterator
begin() const;

Returns an iterator positioned at the first pair in 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 key and its associated item will have its destructor called.

bool
contains(const K& key) const; 

Returns true if there exists a key j in self that compares equal to key, otherwise returns false.

bool
contains
  (bool (*fn)(const_reference,void*), void* d) const;

Returns true if there exists an association a in self such that the expression ((*fn)(a,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.

iterator
end();
const_iterator
end() const;

Returns an iterator positioned "just past" the last association in self.

size_type
entries() const; 

Returns the number of associations in self.

float
fillRatio() const; 

Returns the ratio entries()/capacity().

bool
find(const K& key, Key& r) const; 

If there exists a key j in self that compares equal to key, assigns j to r and returns true. Otherwise, returns false and leaves the value of r unchanged.

bool
find (bool (*fn)(const_reference,void*),
      void* d,std::pair<K,T>& r) const;

If there exists an association a in self such that the expression ((*fn)(a,d)) is true, assigns a to r 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
findValue(const K& key, T& r) const; 

If there exists a key j in self that compares equal to key, assigns the item associated with j to r and returns true. Otherwise, returns false and leaves the value of r unchanged.

bool
findKeyValue(const K& key, K& kr, T& tr) const; 

If there exists a key j in self that compares equal to key, assigns j to kr, assigns the item associated with j to tr, and returns true. Otherwise, returns false and leaves the values of kr and tr unchanged.

bool
insert(const K& key, const T& a); 

Adds key with associated item a to the collection. Returns true.

bool
isEmpty() const; 

Returns true if there are no items in the collection, false otherwise.

const K&
minElement() const;
const K&
maxElement() const;

Returns a reference to the minimum or maximum key in the collection. Type K must have well-defined less-than semantics (K::operator<(const K&) or equivalent).

size_type
occurrencesOf(const K& key) const; 

Returns the number of keys j in self that compares equal to key.

size_type
occurrencesOf
  (bool (*fn)(const_reference,void*),void* d) const;

Returns the number of associations a in self such that the expression((*fn)(a,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 K& key); 

Removes the first association with key j in self such that j compares equal to key and returns true. Returns false if there is no such association.

bool
remove(bool (*fn)(const_reference,void*), void* d); 

Removes the first association a in self such that the expression ((*fn)(a,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 K& key); 

Removes all associations with key j in self where j compares equal to key. Returns the number of items removed.

size_type
removeAll(bool (*fn)(const_reference,void*), void* d);

Removes all associations a in self such that the expression ((*fn)(a,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 multimap with a capacity of sz. resize then copies every element of self into the new container and finally swaps the internal representation of the new container with self.

rw_hashmultimap<K,T,H,EQ,A>&
std();
const rw_hashmultimap<K,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 accessibility to the C++-standard interface and interoperability with other software components that make use of the C++-standard collections.

RWvostream&
operator<<(RWvostream& strm, 
           const RWTValHashMultiMap<K,T,H,EQ,A>& coll);
RWFile&
operator<<(RWFile& strm, 
           const RWTValHashMultiMap<K,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, 
           RWTValHashMultiMap<K,T,H,EQ,A>& coll);
RWFile&
operator>>(RWFile& strm, 
           RWTValHashMultiMap<K,T,H,EQ,A>& coll);

Restores the contents of the collection coll from the input stream strm.

RWvistream&
operator>>(RWvistream& strm, 
           RWTValHashMultiMap<K,T,H,EQ,A>*& p);
RWFile&
operator>>(RWFile& strm, RWTValHashMultiMap<K,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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