components.queue

Interface QueueKernel<T>

All Superinterfaces:

Standard<Queue<T>>

All Known Subinterfaces:

Queue<T>

All Known Implementing Classes:

Queue1L, QueueDL, QueueSecondary

public interface QueueKernel<T>
extends Standard<Queue<T>>

Queue kernel component containing method headers and contracts for all methods that will directly interact with the label representations of all Queue implementations. All sub-interface methods should use only these methods to perform operations on the Queue.

Author:

Matthew Shoemaker

Method Summary

Modifier and Type	Method and Description
T	dequeue() Removes the entry at the front of this.
void	enqueue(T entry) Adds entry to the back of this.
T	front() Reports, but does not remove, the entry at the front of this.
int	length() Reports the number of entries in the queue.
T	replaceFront(T entry) Replaces the entry at the front of this with entry, and returns the entry at the front of #this.

Methods inherited from interface components.standard.Standard

clear, newInstance, transferFrom

Method Detail

enqueue

void enqueue(T entry)

Adds entry to the back of this.

Parameters:

entry - entry to be enqueued

Updates:

this

Ensures:

this = #this * entry

dequeue

T dequeue()

Removes the entry at the front of this.

Returns:

the front of the queue

Updates:

this

Ensures:

 dequeue = [entry at the front of the queue] and
 [the front of the queue is removed]
 

length

int length()

Reports the number of entries in the queue.

Returns:

|this|

Ensures:

length = [number of entries in the queue]

front

T front()

Reports, but does not remove, the entry at the front of this.

Returns:

a reference to the entry at the front of this

Requires:

#this.length > 0

Ensures:

front = [front of the queue]

replaceFront

T replaceFront(T entry)

Replaces the entry at the front of this with entry, and returns the entry at the front of #this.

Parameters:

entry - new front of the queue

Returns:

entry at the front of #this

Updates:

this

Requires:

#this.length > 0

Ensures:

 replaceFront = #this.front and
 this = (#this with the front of the queue swapped with  entry)