ptolemy.domains.fsm.kernel
Class RelationList

java.lang.Object
  ptolemy.domains.fsm.kernel.RelationList

public class RelationList
extends java.lang.Object

A RelationList object contains a list of relations of a guard expression. Relations are comparison operations, for example "x >= 10", where x is a variable. This class provides facilities for measuring how far the expression is from the threshold; for example, if x = 7, then the distance to the threshold is 3. Moreover, it provides a mechanism for recording the current distance (via a "commit") and then later accessing that distance and comparing it against the current distance. The information includes relation type and the difference information. (See ParseTreeEvaluatorForGuardExpression for the detailed explanation of relation type and difference.) This attribute is non-persistent and will not be exported into MoML.

This class is designed to be used with ParseTreeEvaluatorForGuardExpression. The common usage would be like:

Construct a relation list for a transition with the first argument of the constructor as that transition.

 _relationList = new RelationList();
 

Associate the relation list with the an object of ParseTreeEvaluatorForGuardExpression

 _parseTreeEvaluator =
 new ParseTreeEvaluatorForGuardExpression(_relationList, getErrorTolerance());
 

See Transition for the detailed usage.

Since:

Ptolemy II 4.0

Version:

$Id: RelationList.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Haiyang Zheng

Accepted Rating:

Red (hyzheng)

Proposed Rating:

Yellow (hyzheng)

Field Summary

private int	_maximumDifferenceIndex
private java.util.LinkedList	_relationList

Constructor Summary

RelationList()
Construct a relation list.

Method Summary

void	addRelation(int type, double difference) Construct a relation node with the given type and difference information of a relation, and add it to the end of the relation list.
void	commitRelationValues() Record the current relation values so that when getPreviousMaximumDistance() is called, these recorded values are used.
void	destroy() Destroy the relation list by deleting all the contained elements.
double	getMaximumDifference() Return the maximum current difference of all the relations by iterating the relation list.
double	getPreviousMaximumDistance() Return the previous difference of the relation that has the maximum current difference.
boolean	hasEvent() Return true if there exists an event caused by the type change of any relation.
boolean	isEmpty() Return true if the relation list is empty.
int	length() Return the number of relations in the relation list.
void	resetRelationList() Reset the relation list by resetting each relation node.
void	setRelation(int relationIndex, int type, double difference) Update the relation in the relation list referred by the relation index argument with the given type and difference information.

Methods inherited from class java.lang.Object

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

Field Detail

_maximumDifferenceIndex

private int _maximumDifferenceIndex

_relationList

private java.util.LinkedList _relationList

Constructor Detail

RelationList

public RelationList()

Construct a relation list.

Method Detail

addRelation

public void addRelation(int type,
                        double difference)

Construct a relation node with the given type and difference information of a relation, and add it to the end of the relation list.

Parameters:

type - The relation type of the relation.

difference - The difference of the relation.

resetRelationList

public void resetRelationList()

Reset the relation list by resetting each relation node.

commitRelationValues

public void commitRelationValues()

Record the current relation values so that when getPreviousMaximumDistance() is called, these recorded values are used.

See Also:

getPreviousMaximumDistance()

destroy

public void destroy()

Destroy the relation list by deleting all the contained elements.

getPreviousMaximumDistance

public double getPreviousMaximumDistance()

Return the previous difference of the relation that has the maximum current difference. This is the value as of the last call to commitRelationValues().

Returns:

The previous distance of a relation.

See Also:

commitRelationValues()

hasEvent

public boolean hasEvent()

Return true if there exists an event caused by the type change of any relation.

Returns:

True If there exits an event.

isEmpty

public boolean isEmpty()

Return true if the relation list is empty.

Returns:

True If the relation list is empty.

length

public int length()

Return the number of relations in the relation list.

Returns:

the number of relations in the relation list.

getMaximumDifference

public double getMaximumDifference()

Return the maximum current difference of all the relations by iterating the relation list.

Returns:

maximumDistance The maximum current distance.

setRelation

public void setRelation(int relationIndex,
                        int type,
                        double difference)

Update the relation in the relation list referred by the relation index argument with the given type and difference information.

Parameters:

relationIndex - The position of the relation in the relation list.

type - The current type of the relation.

difference - The current difference of the relation.