Class FOR_ListIterator

java.lang.Object

simula.runtime.FOR_ListIterator

All Implemented Interfaces:

Iterator<Boolean>

public final class FOR_ListIterator
extends Object
implements Iterator<Boolean>

The Implementation of the for-statement is a bit tricky. The basic idea is to create a ForList iterator that iterates over a set of ForElt iterators. The following subclasses of ForElt are defined:

• FOR_SingleElt with basic types T control variable
• FOR_SingleTValElt with Text type control variable
• FOR_StepUntil with numeric types
• FOR_WhileElt with basic types T control variable
• FOR_WhileTValElt representing For t:= while with text value assignment

Each of which has a boolean method 'hasNext' indicating whether this for-element is exhausted. All parameters to these classes are transferred 'by name'. This is done to ensure that all expressions are evaluated in the right order. The assignment to the 'control variable' is done within the various for-elements when the 'next' method is invoked.

Simula for-statement for-list iterator

Field Summary

Fields

Modifier and Type	Field	Description
(package private) final FOR_Element[]	forElt	The ForElt array.
(package private) int	index	Current index into the ForElt array.

Constructor Summary

Constructors

Constructor	Description
FOR_ListIterator(FOR_Element... forElt)	Create a ForListIterator consisting of an array of ForElt Iterators.

Method Summary

Modifier and Type	Method	Description
boolean	hasNext()	Returns true if the iteration has more elements.
Boolean	next()	Update the control variable with the next value if any.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Field Details

forElt

final FOR_Element[] forElt

The ForElt array.

index

int index

Current index into the ForElt array.

Constructor Details

FOR_ListIterator

public FOR_ListIterator(FOR_Element... forElt)

Create a ForListIterator consisting of an array of ForElt Iterators.

Parameters:

forElt - an array of ForElt Iterators.

Method Details

hasNext

public boolean hasNext()

Returns true if the iteration has more elements.

Specified by:

hasNext in interface Iterator<Boolean>

Returns:

true if the iteration has more elements

next

public Boolean next()

Update the control variable with the next value if any.

Specified by:

next in interface Iterator<Boolean>

Returns:

true if the control variable was updated; otherwise false.