scranton.stack
Class StackViaLinear1

java.lang.Object
  scranton.stack.StackViaLinear1

All Implemented Interfaces:

Stack

public class StackViaLinear1

extends java.lang.Object

implements Stack

An implementation of the Stack interface applying the the Linear1 class via composition. Invariant: The class warranty is voided is a client directly applies any Linear1 class method.

Field Summary

protected Linear1

actual The stack is provided through aggregation, as a protected attribute within the class.

Constructor Summary

StackViaLinear1()
Constructs an empty stack.

Method Summary

Stack	factory()
boolean	isEmpty() Stack does not change, returns true iff the stack is empty.
java.lang.Object	pop() Decrease the size of the stack by one by removing and returning the object at the top.
void	push(java.lang.Object item) Increase the size of the stack by one by placing item as the new top of the stack.
java.lang.Object	topOf() Stack does not change, returns the reference to the top object in the stack.
java.lang.String	toString() Returns a string representation of the stack.

Methods inherited from class java.lang.Object

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

Field Detail

actual

protected Linear1 actual

The stack is provided through aggregation, as a protected attribute within the class.

Constructor Detail

StackViaLinear1

public StackViaLinear1()

Constructs an empty stack.

Method Detail

isEmpty

public boolean isEmpty()

Description copied from interface: Stack

Stack does not change, returns true iff the stack is empty.

Specifications:

S'=S
Return S==()

Specified by:

isEmpty in interface Stack

Returns:

boolean this==().

topOf

public java.lang.Object topOf()

Description copied from interface: Stack

Stack does not change, returns the reference to the top object in the stack.

Specifications:

S!=()S'=S
Return a_n-1

Specified by:

topOf in interface Stack

Returns:

Object Top of stack.

push

public void push(java.lang.Object item)

Description copied from interface: Stack

Increase the size of the stack by one by placing item as the new top of the stack.

Specifications:

S'=(S, obj)

Specified by:

push in interface Stack

Parameters:

item - The new top of stack

pop

public java.lang.Object pop()

Description copied from interface: Stack

Decrease the size of the stack by one by removing and returning the object at the top. Note: that the stack cannot be empty.

Specifications:

S!=()S = (S', a_n-1)
Return: a_n-1

Specified by:

pop in interface Stack

Returns:

Object Top of stack.

factory

public Stack factory()

toString

public java.lang.String toString()

Description copied from interface: Stack

Returns a string representation of the stack. The format is, "TOP[O_top\t...\tO_bottom]BOTTOM"

Specified by:

toString in interface Stack