org.adroitlogic.x.utils

Class LazyStack<T>

java.lang.Object

org.adroitlogic.x.utils.LazyStack<T>

public class LazyStack<T>
extends Object

This is a wrapper implementation for the Stack, which will construct the actual stack object only at the first push operation

Since:

17.07

Author:

Udith Gunaratna

Constructor Summary

Constructors

Constructor and Description
LazyStack()

Method Summary

Modifier and Type	Method and Description
boolean	empty() Tests if this stack is empty.
Optional<T>	peek() Looks at the object at the top of this stack without removing it from the stack.
Optional<T>	pop() Removes the object at the top of this stack and returns an Optional of that object as the value of this function.
T	push(T item) Pushes an item onto the top of this stack.
int	search(Object o) Returns the 1-based position where an object is on this stack.

Methods inherited from class java.lang.Object

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

Constructor Detail

LazyStack

public LazyStack()

Method Detail

push

public T push(T item)

Pushes an item onto the top of this stack. This will additionally construct the stack if this is the first ever push operation.

Parameters:

item - the item to be pushed onto this stack

Returns:

the item argument

See Also:

Stack.push(Object)

pop

public Optional<T> pop()

Removes the object at the top of this stack and returns an Optional of that object as the value of this function.

Returns:

An Optional with the object at the top of this stack if exists, or Optional.EMPTY otherwise

peek

public Optional<T> peek()

Looks at the object at the top of this stack without removing it from the stack.

Returns:

An Optional with the object at the top of this stack if exists, or Optional.EMPTY otherwise

empty

public boolean empty()

Tests if this stack is empty.

Returns:

true if and only if this stack contains no items; false otherwise.

search

public int search(Object o)

Returns the 1-based position where an object is on this stack.

If the object o occurs as an item in this stack, this method returns the distance from the top of the stack of the occurrence nearest the top of the stack; the topmost item on the stack is considered to be at distance 1. The equals method is used to compare o to the items in this stack.

Parameters:

o - the desired object.

Returns:

the 1-based position from the top of the stack where the object is located; the return value -1 indicates that the object is not on the stack.