#include <rw/tvhmmap.h> RWTValHashMultiMap<K,T,H,EQ> m;
RWTValHashMultiMap requires the Standard C++ Library.
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> may contain multiple keys that are equivalent to each other. (RWTValHashMap<K,T,H,EQ> 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 Standard C++ Library.
Isomorphic.
//
// tvhmmrat.cpp
//
#include<rw/tvhmmap.h>
#include<iostream.h>
#include<rw/cstring.h>
struct silly_hash{
unsigned long operator()(RWCString x) const
{ return x.length() * (long)x[0]; }
};
int main(){
RWCString trd = "Third";
RWTValHashMultiMap<RWCString,int,silly_hash,equal_to<RWCString> >
contest;
contest.insert("First", 7);
contest.insert(trd,3);
contest.insert(trd,6); // self contains two distinct values
//equivalent to trd
contest.insert("Second",2);
contest.resize(8);
cout << "The table is " << contest.fillRatio() * 100.0
<< "% full<< endl;
return 0;
}
Program Output:
The table is 50% full
Class RWTValHashMap<K,T,H,EQ> 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> is the C++-standard collection that serves as the underlying implementation for this collection.
typedef rw_hashmultimap<K,T,H,EQ> container_type; typedef container_type::iterator iterator; typedef container_type::const_iterator const_iterator; typedef container_type::size_type size_type; typedef pair <const K,T> value_type; typedef pair <const K,T>& reference; typedef const pair<const K,T>& const_reference;
RWTValHashMultiMap<K,T,H,EQ>();
Constructs an empty map.
RWTValHashMultiMap<K,T,H,EQ> (const rw_hashmultimap<K,T,H,EQ>& m);
Constructs a map by copying all elements of m.
RWTValHashMultiMap<K,T,H,EQ> (const RWTValHashMultiMap<K,T,H,EQ>& rwm);
Copy constructor.
RWTValHashMultiMap<K,T,H,EQ> (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>& operator=(const RWTValHashMultiMap<K,T,H,EQ>& m); RWTValHashMultiMap<K,T,H,EQ>& operator=(const rw_hashmultimap<K,T,H,EQ>& m);
Destroys all elements of self and replaces them by copying all associations from m.
bool operator==(const RWTValHashMultiMap<K,T,H,EQ>& m) const; bool operator==(const rw_hashmultimap<K,T,H,EQ>& 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.
void applyToKeyAndValue(void (*fn)(const K&, T&, void*),void* d); void applyToKeyAndValue (void (*fn)(const K&,const T&,void*), void* d) const;
This is a deprecated version of the apply member above. It behaves exactly the same as apply.
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,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 insertKeyAndValue(const K& key, const T& a);
This is a deprecated version of the insert member above. It behaves exactly the same as insert.
bool isEmpty() const;
Returns true if there are no items in the collection, false otherwise.
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>& std(); const rw_hashmultimap<K,T,H,EQ>& std() const;
Returns a reference to the underlying C++-standard 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>& coll);
RWFile&
operator<<(RWFile& strm,
const RWTValHashMultiMap<K,T,H,EQ>& 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>& coll);
RWFile&
operator>>(RWFile& strm, RWTValHashMultiMap<K,T,H,EQ>& coll);
Restores the contents of the collection coll from the input stream strm.
RWvistream& operator>>(RWvistream& strm, RWTValHashMultiMap<K,T,H,EQ>*& p); RWFile& operator>>(RWFile& strm, RWTValHashMultiMap<K,T,H,EQ>*& 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.