Stack¶

A Stack is a collection of any type in kOS. Stacks work according to Last-In first-out principle. It may be useful to contrast Stack with Queue to better understand how both structures work. You can read more about stacks on Wikipedia.

Using a stack¶

SET S TO STACK().
S:PUSH("alice").
S:PUSH("bob").

PRINT S:POP. // will print 'bob'
PRINT S:POP. // will print 'alice'

Structure¶

structure Stack¶

Members¶
Suffix	Type	Description
`PUSH(item)`	None	add item to the top of the stack
`POP()`	any type	returns the item on top of the stack and removes it
`PEEK()`	any type	returns the item on top of the stack without removing it
`LENGTH`	integer	number of elements in the stack
`CLEAR()`	None	remove all elements
`ITERATOR`	`Iterator`	for iterating over the stack
`COPY`	`Stack`	a new copy of this stack
`CONTAINS(item)`	boolean	check if stack contains an item
`EMPTY`	boolean	check if stack if empty
`DUMP`	string	verbose dump of all contained elements

Stack:PUSH(item)¶

Parameters:	item – (any type) item to be added

Adds the item to the top of the stack.

Stack:POP()¶: Returns the item on top of the stack and removes it.

Stack:PEEK()¶: Returns the item on top of the stack without removing it.

Stack:CLEAR()¶: Removes all elements from the stack.

Stack:LENGTH¶

Type:	integer
Access:	Get only

Returns the number of elements in the stack.

Stack:ITERATOR¶

Type:	`Iterator`
Access:	Get only

An alternate means of iterating over a stack. See: Iterator.

Stack:COPY¶

Type:	`Stack`
Access:	Get only

Returns a new stack that contains the same thing as the old one.

Stack:CONTAINS(item)¶

Parameters:	index – (integer) starting index (from zero)
Returns:	boolean

Returns true if the stack contains an item equal to the one passed as an argument

Stack:EMPTY¶

Type:	boolean
Access:	Get only

Returns true if the stack has zero items in it.

Stack:DUMP¶

Type:	string
Access:	Get only

Returns a string containing a verbose dump of the stack’s contents.