class Fifo_iterator

Class Fifo_iterator: Enables access to the Fifos while hiding their implementation in shared memory.

Public Methods

creator and destructor of the iterators

Member function that iterate over the fifos in the system

Operators on the fifo iterator

Documentation

Class Fifo_iterator: Enables access to the Fifos while hiding their implementation in shared memory.

The Fifos reside in shared memory as a fixed length array. An available slot may or may not be occupied by a Fifo. Fifo_iterator allows to iterate in forward direction over the occpupied slots (the unoccupied slots are ignored).

A typical use of the iterator is as follows:

    // creates an initialises the iterator to the INPUT fifo
    Fifo_iterator it_inp(fifos, "INPUT");
    if ( ! it_inp.valid() )
       cout << "INPUT fifo not found";

    // creates an arbitrary iterator - fifos is a pointer to the Fifo_system
    Fifo_iterator it( fifos );
    // iterates over the all the fifos of the system fifos
    for ( it.first(); ! it.is_done(); it.next() ) {
       if ( ! (*it)->in_use() ) {
          // this should never happen as we iterate only over the fifos
          // that are in use !
       }
       if ( it != it_inp ) {
          // do something
       }
    }
    

Modifications:

creator and destructor of the iterators

Fifo_iterator( Fifo_system* the_system)

Constructor for an iterator on the fifo system the_system.

Parameters:

the_system - : Pointer to the fifo system where the fifos are located

Returns:

Pointer to the first fifo that is in use or an iterator that is bigger than the iterator last.

Fifo_iterator( Fifo_system* the_system, const char* fifo_name)

Constructor for an iterator that points to the fifo with name fifo_name.

Parameters:

the_system - : Pointer to the fifo system where the fifos are located

Returns:

Pointer to the fifo fifo_name or an iterator that is bigger than the iterator last.

Fifo_iterator( Fifo_iterator*)

Copy constructor: Initialises the iterator to the same fifo as iterator.

Parameters:

- Fifo_iterator a valid fifo iterator

Returns:

Iterator to the same fifo.

Member function that iterate over the fifos in the system

void first()

Puts the iterator on the first fifo that is in use

void last()

Puts the iterator on the last fifo that is in use

void next()

Increments the iterator to the next fifo (or makes it bigger than last)

int is_valid() const

Returns -1 if the fifo iterator points to a valid fifo. A valid fifo defined as one that resides between the first and the last iterator.

int is_done() const

Returns -1 if the iterator is bigger than last

Fifo_iterator& operator++()

Same as next - for convenience only

Operators on the fifo iterator

Fifo_iterator& operator=(const Fifo_iterator &rhs)

Assignment operator - assigns the lhs iterator to the rhs. Note: This can change the fifo_system to which the lhs iterator originally pointed to.

Fifo* get_fifo() const

Dereferences the iterator: Returns a pointer to the Fifo to which the iterator points

Fifo* operator*() const

Dereferences the iterator: Returns a pointer to the Fifo to which the iterator points

BOOL operator==(const Fifo_iterator &rhs ) const

Overloaded == operator. Returns true if the iterator points to the same fifo in the same system.

BOOL operator!=(const Fifo_iterator &rhs ) const

Overloaded != operator. Returns true if the iterator points to a different fifo in a possibly different system.

This class has no child classes.

Author:

C.Witzig
Date: Nov 30, 1997

Version:

Last update: Nov 30, 1997

Alphabetic index HTML hierarchy of classes or Java