operators
Class PSFor

java.lang.Object
  operators.PSFor

All Implemented Interfaces:

PSFlowOperator, PSObject, PSOperator

public class PSFor

extends java.lang.Object

implements PSFlowOperator

Implements PSFlowOperator interface.

Methods such as getOperatorToken() are inherited from PSFlowOperator interface which, in turn, are inherited from PSOperator. This concrete class is responsible for creating a for block: for(i=j;i<=l;i+=k) which executes an array.

Constructor Summary

PSFor()

Method Summary

void	action(PSStack s) Repeats the executable array as a for loop: for(i=j;i<=l;i+=k).
java.lang.String	getOperatorToken() Returns the token identifying this operator.
boolean	isValid(PSStack s) Checks if it valid to use this operator now.

Methods inherited from class java.lang.Object

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

Constructor Detail

PSFor

public PSFor()

Method Detail

getOperatorToken

public java.lang.String getOperatorToken()

Returns the token identifying this operator.

Returns the name of the operand that this concrete class simulates, here "for".

Precondition : A valid operator class has been created.
Postcondition : A string is returned, labeling the semantics of this class.

Specified by:

getOperatorToken in interface PSOperator

Returns:

The token identifying this operator.

isValid

public boolean isValid(PSStack s)
                throws PSSyntaxException

Checks if it valid to use this operator now.

For can occur only if 3 numbers and an executable array is given.

Precondition : A valid instance of PSStack with 3 PSNumbers and an executable array on top.
Postcondition : A reply to the question whether the operator can perfom its defined behaviour.

Specified by:

isValid in interface PSOperator

Parameters:

s - A reference to PSStack instance.

Returns:

True if the operation can be executed, false otherwise.

Throws:

PSSyntaxException - The syntax of the token is wrong.

action

public void action(PSStack s)

Repeats the executable array as a for loop: for(i=j;i<=l;i+=k).

Precondition : A valid stack is given to method with 3 PSNumbers and an executable array on top.
Postcondition : The array will be executed based on the for parmeters.

Specified by:

action in interface PSFlowOperator

Parameters:

s - The Runtime Stack which contains the parameters and the array.