RWTFunctorMapR2

Module:  Threads   Package:  Functor Map, subpackage of Functor

RWTFunctorMapR2   RWTFunctorR2<SR,Key,S1>

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• Header File
• Description
• Example
• Public Typedefs
• Public Constructors
• Public Destructor
• Public Operators
• Public Member Functions

Members

add() clear() contains() entries()

find() getDefault() hash_function key_type

operator()() operator=() remove() resize()

RWTFunctorMapR2() setDefault() ~RWTFunctorMapR2()

#include <rw/functor/map/RWTFunctorMapR2.h>

The RWTFunctorMapR2 class represents the functor maps that take two arguments at invocation time, and return a value. Since one of these arguments is the key into the map, the functors that are held in the map take only one argument; they are RWTFunctorR1 functors.

Functor maps allow functors to be grouped together in a key/value table structure. They add functors to the map with a corresponding key of type key_type, later using it to invoke the desired functor.

#include <rw/cstring.h>
#include <rw/rwdate.h>
#include <rw/functor/functorR1.h>
#include <rw/functor/map/RWTFunctorMapR2.h>

// Functions that we want to wrap in functors:
class BankAccount{
   float getBalance(RWDate date){ return 1234.56; }
   float getInterest(RWDate date){ return 61.51; }
};

int main () {

  BankAccount currentAcct;

  // Create new RWTFunctorR1s to be the values in the map.
  RWTFunctorR1<float,RWDate> balanceFunctor=rwtMakeFunctorR1(
     (float(*)(RWDate))0,currentAcct,&BankAccount::getBalance);
  RWTFunctorR1<float,RWDate> interestFunctor=rwtMakeFunctorR1(
     (float(*)(RWDate))0,currentAcct,&BankAccount::getInterest);

  // Create keys with which to associate the values.
  RWCString balanceKey = "balance";
  RWCString interestKey = "interest";

  // Declare a new map. A complete, but empty instance now exists.
  RWTFunctorMapR2<float,RWCString,RWDate>  fmap(RWCString::hash);

  // Add something to the map to make it useful.
  fmap.add(balanceKey, balanceFunctor);
  fmap.add(interestKey, interestFunctor);

  // Create an RWDate to represent the date for which we want info.
  RWDate today;

  // Invoking the map with the key "balance" results in the 
  // balanceFunctor being called.
  float balance = fmap("balance", today);

  // Invoking the map with the key "interest" results in the 
  // interestFunctor being called.
  float interest = fmap("interest", today);

  cout << "Account balance as of " << today << " is "
       << balance << endl;
  cout << "Interest earned as of " << today << " is "
       << interest << endl;

  return 0;
}


 OUTPUT

    Account balance as of 07/14/99 is 1234.56
    Interest earned as of 07/14/99 is 61.51

typedef Key key_type;

The type of the key.

typedef unsigned  (*hash_function)(const Key&);

The signature of the hash function.

RWTFunctorMapR2(hash_function hf, 
                size_t size = RW_FUNCTOR_MAP_CAPACITY);

Constructs an empty map instance. This creates a complete RWTFunctorMapR2 instance, but the map will contain no entries. The default size parameter is set to RW_FUNCTOR_MAP_CAPACITY, which is set in rw/functor/map/pkgdefs.h.

RWTFunctorMapR2(const RWTFunctorMapR2<SR,key_type,S1>& second);

Copy constructor. Constructs a new functor map instance which then shares its representation with the original functor map.

~RWTFunctorMapR2();

Destructor.

RWTFunctorMapR2<SR,key_type,S1>& 
operator=(const RWTFunctorMapR2<SR,key_type,S1>& second);

Assignment operator. Binds this functor map instance to the representation of the second map instance.

SR 
operator()(key_type key, S1 s1) const;

Invokes the functor in the map that is associated with the given key. If there is no matching key, and a default functor has been set, calls the default. If there is no default, and no matching key, throw an RWTHRInternalError exception.

bool 
add(key_type key, RWTFunctorR1<SR,S1> functor);

Adds the specified functor to the functor map with the corresponding key. If an entry already exists with an equivalent key, the addition fails and false is returned.

void 
clear();

Clears the functor map of all entries.

bool 
contains(key_type key) const; 

Returns true if the functor map contains an entry with an equivalent key.

size_t 
entries() const;

Returns the number of entries in the functor map.

bool 
find(key_type key, RWTFunctorR1<SR,S1>& functor) const;

Finds the entry in the functor map with the equivalent key, and returns it via the RWTFunctorR1 reference parameter. Returns true if the key is found, and otherwise returns false. In the case where a matching key is not found, but a default functor exists: the reference parameter is set to the default functor, but returns false. If no match is found, and there is no default functor, an RWTHRInternalError exception is thrown.

RWTFunctorR1<SR,S1> 
getDefault() const;

Returns the map's default functor. This functor is used whenever an invalid key accesses the functor map.

bool 
remove(key_type key);

Removes the entry, if it exists, with the equivalent key, and returns true. If no such entry exists, returns false.

void 
resize(size_t size);

Changes the size of the map to size. This is an expensive operation, since the entire map must be re-created. Size can be set at construction time via the size parameter.

void 
setDefault(RWTFunctorR1<SR,S1> functor);

Sets a functor as the default functor. This functor is used whenever an invalid key is used to access the functor map.

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