prefuse.visual.expression
Class GroupExpression

java.lang.Object
  prefuse.data.expression.AbstractExpression
      prefuse.visual.expression.GroupExpression

All Implemented Interfaces:

java.util.EventListener, ExpressionListener, Expression, Function

Direct Known Subclasses:

GroupSizeFunction, InGroupPredicate, QueryExpression

public abstract class GroupExpression
extends AbstractExpression
implements Function

Abstract base class for Expression instances dealing with data groups within a Visualization. Maintains an Expression that serves as the paremter to this Function; this Expression should return a valid group name when evaluated on a given Tuple.

Author:

jeffrey heer

Field Summary

protected Expression

m_group

Fields inherited from interface prefuse.data.expression.Function

VARARGS

Constructor Summary

protected	GroupExpression() Create a new GroupExpression.
protected	GroupExpression(java.lang.String group) Create a new GroupExpression over the given group name.

Method Summary

void	addParameter(Expression e) Attempts to add the given expression as the group expression.
protected java.lang.String	getGroup(Tuple t) Evaluate the group name expression for the given Tuple
int	getParameterCount() Get the maximum number of parameters accepted by this Function.
java.lang.String	toString()

Methods inherited from class prefuse.data.expression.AbstractExpression

addChildListeners, addExpressionListener, expressionChanged, fireExpressionChange, get, getBoolean, getDouble, getFloat, getInt, getLong, hasListeners, removeChildListeners, removeExpressionListener, visit

Methods inherited from class java.lang.Object

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

Methods inherited from interface prefuse.data.expression.Function

getName

Methods inherited from interface prefuse.data.expression.Expression

addExpressionListener, get, getBoolean, getDouble, getFloat, getInt, getLong, getType, removeExpressionListener, visit

Field Detail

m_group

protected Expression m_group

Constructor Detail

GroupExpression

protected GroupExpression()

Create a new GroupExpression.

GroupExpression

protected GroupExpression(java.lang.String group)

Create a new GroupExpression over the given group name.

Parameters:

group - the data group name

Method Detail

getGroup

protected java.lang.String getGroup(Tuple t)

Evaluate the group name expression for the given Tuple

Parameters:

t - the input Tuple to the group name expression

Returns:

the String result of the expression

addParameter

public void addParameter(Expression e)

Attempts to add the given expression as the group expression.

Specified by:

addParameter in interface Function

Parameters:

e - the parameter sub-expression

See Also:

Function.addParameter(prefuse.data.expression.Expression)

getParameterCount

public int getParameterCount()

Description copied from interface: Function

Get the maximum number of parameters accepted by this Function.

Specified by:

getParameterCount in interface Function

Returns:

the maximum number of parametes accepted, or Function.VARARGS is the number is variable.

See Also:

Function.getParameterCount()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

See Also:

Object.toString()