operators
Class PSNewpath

java.lang.Object
  operators.PSNewpath

All Implemented Interfaces:

PSObject, PSOperator, PSPathOperator

public class PSNewpath

extends java.lang.Object

implements PSPathOperator

Implements PSPathOperator interface.

Methods such as getOperatorToken() are inherited from PSPathOperator interface which, in turn, are inherited from PSOperator. This concrete class is responsible for the deleting everything in the Graphics Stack up to the last stroke command and setting the current position and the last move to null. The Runtime Stack is not affected by this operation.

Constructor Summary

PSNewpath()

Method Summary

void	action(PSStack s, PSPath p) Deletes everything in the Graphics Stack up to the last stroke command and setting the current position and the last move to null.
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

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

Constructor Detail

PSNewpath

public PSNewpath()

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 "newpath".

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.

The creation of a new path can occur any time.

Precondition : A valid instance of PSStack is given.
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 an instance of PSStack.

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,
                   PSPath p)

Deletes everything in the Graphics Stack up to the last stroke command and setting the current position and the last move to null.

When a new PSPath is created, every variable which represents position or state is reset.

Precondition : A valid stack is given to method.
Postcondition : Unstroked commands will be lost and the current position and last move variables will be reset.

Specified by:

action in interface PSPathOperator

Parameters:

s - The stack which serves no actual purpose here.

p - The Graphics Stack.