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©Copyright 1996 Rogue Wave Software

RWTValMap<K,T,C>

• Synopsis
• Standard C++ Library Dependent!
• Description
• Persistence
• Examples
• Related Classes
• Public Typedefs
• Public Constructors
• Public Member Operators
• Public Member Functions
• Related Global Operators

#include <rw/tvmap.h> 
RWTValMap<K,T,C> m;

This class maintains a collection of keys, each with an associated item of type T. Order is determined by the key according to a comparison object of type C. C must induce a total ordering on elements of type K via a public member

bool operator()(const K& x, const K& y) const

which returns true if x and its partner should precede y and its partner within the collection. The structure less<T> from the C++-standard header file <functional> is an example.

RWTValMap<K,T,C> will not accept a key that compares equal to any key already in the collection. (RWTValMultiMap<K,T,C> may contain multiple keys that compare equal to each other.) Equality is based on the comparison object and not on the == operator. Given a comparison object comp, keys a and b are equal if

!comp(a,b) && !comp(b,a).

Isomorphic.

In this example, a map of RWCStrings and RWDates is exercised.

//

// tvmbday.cpp
//
#include <rw/tvmap.h>
#include <rw/cstring.h>
#include <rw/rwdate.h>
#include <iostream.h>

main(){
  RWTValMap<RWCString, RWDate, less<RWCString> > birthdays;

  birthdays.insert("John", RWDate(12, "April",1975));
  birthdays.insert("Ivan", RWDate(2, "Nov", 1980));

  // Alternative syntax:
  birthdays["Susan"] = RWDate(30, "June", 1955);
  birthdays["Gene"] = RWDate(5, "Jan", 1981);

  // Print a birthday:
  cout << birthdays["John"] << endl;
  return 0;
}

Program Output:
04/12/75

Class RWTValMultiMap<K,T,C> offers the same interface to a collection that accepts multiple keys that compare equal to each other. RWTValSet<T,C> maintains a collection of keys without the associated values.

Class map<K,T,C,allocator> is the C++-standard collection that serves as the underlying implementation for this collection.

typedef map<K,T,C,allocator>                   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;

RWTValMap<K,T,C>(const C& comp = C());

Constructs an empty map with comparator comp.

RWTValMap<K,T,C>(const container_type& m);

Constructs a map by copying all elements of m.

RWTValMap<K,T,C>(const RWTValMap<K,T,C>& rwm);

Copy constructor.

RWTValMap<K,T,C>(const value_type* first,
     const value_type* last,const C& comp = C());

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

RWTValMap<K,T,C>&
operator=(const RWTValMap<K,T,C>& m);
RWTValMap<K,T,C>&
operator=(const container_type& m);

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

bool
operator<(const RWTValMap<K,T,C>& m) const;
bool
operator<(const container_type & m) const;

Returns true if self compares lexicographically less than m, otherwise returns false. Assumes that type K has well-defined less-than semantics (T::operator<(const K&) or equivalent).

bool
operator==(const RWTValMap<K,T,C>& m) const;
bool
operator==(const container_type & 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 pairs that compare equal to each other.

T&
operator[](const K& key);

Looks up key and returns a reference to its associated item. If the key is not in the dictionary, then it will be added with an associated item provided by the default constructor for type T.

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& key, T& a, void* d);

void yourfun(const K& key, 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.

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.

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 if the insertion is successful, otherwise returns false. The function will return true unless the collection already holds an association with the equivalent key.

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 compare 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 such that 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.

map<K,T,C,allocator>&
std();
const map<K,T,C,allocator>&
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 access to the C++-standard interface as well as interoperability with other software components that make use of the C++-standard collections.

RWvostream&
operator<<(RWvostream& strm, const RWTValMap<K,T,C>& coll);
RWFile&
operator<<(RWFile& strm, const RWTValMap<K,T,C>& 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, RWTValMap<K,T,C>& coll);
RWFile&
operator>>(RWFile& strm, RWTValMap<K,T,C>& coll);

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

RWvistream&
operator>>(RWvistream& strm, RWTValMap<K,T,C>*& p);
RWFile&
operator>>(RWFile& strm, RWTValMap<K,T,C>*& 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.