ps4
Class Pipe

java.lang.Object
  ps4.Pipe

All Implemented Interfaces:

Simulatable

Direct Known Subclasses:

IntPipe

public abstract class Pipe

extends Object

implements Simulatable

The Pipe abstract class is implemented by each of the pipes in the pipe-and-filter simulation.

Specification Fields

• inputQueue : list(object)
• outputQueue : list(object)
• label : Object
• simulator : Simulator (the simulator that contains this Pipe)

Field Summary

protected List	inQueue
protected Object	label
protected List	outQueue
protected Simulator	sim

Constructor Summary

Pipe(Object label, Simulator sim)

Method Summary

void	checkRep()
Iterator	contentsIterator() Obtain an iterator over the contents of the pipe
Object	extract() Extract an object from the pipe.
void	inject(Object o) Inject an object into the pipe.
boolean	outputAvailable() Check if any output is available from the pipe

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface ps4.Simulatable

simulate

Field Detail

inQueue

protected List inQueue

outQueue

protected List outQueue

label

protected Object label

sim

protected Simulator sim

Constructor Detail

Pipe

public Pipe(Object label,
            Simulator sim)

Requires:

label != null, sim != null

Effects:

constructs a new Pipe with the given label and simulator

Method Detail

checkRep

public void checkRep()

inject

public void inject(Object o)

Inject an object into the pipe.

Requires:

o != null

Effects:

Adds o to the end of the input queue of the pipe.

Modifies:

this

extract

public Object extract()

Extract an object from the pipe.

Requires:

At least one element is in the output queue.

Effects:

Removes the first element from the output queue.

Modifies:

this

Returns:

The first element from the output queue of the pipe.

outputAvailable

public boolean outputAvailable()

Check if any output is available from the pipe

Requires:

none

Returns:

true output is available; i.e. if the output queue contains at least one element.

contentsIterator

public Iterator contentsIterator()

Obtain an iterator over the contents of the pipe

Requires:

none

Effects:

returns an unmodifiable iterator over the list of elements in this pipe, in both the output and input queues, starting with the one that will be output next, and ending with the one most recently input.