org.apache.cocoon.forms.formmodel.algorithms
Class SimpleFormula

java.lang.Object
  org.apache.cocoon.forms.formmodel.algorithms.AbstractBaseAlgorithm
      org.apache.cocoon.forms.formmodel.algorithms.SimpleFormula

All Implemented Interfaces:

Contextualizable, LogEnabled, CalculatedFieldAlgorithm

Direct Known Subclasses:

RepeatedFormula

public class SimpleFormula
extends AbstractBaseAlgorithm

An xreported expression based algorithm.

This algorithm can be used to write simple formulas, examples are :

• 20% VAT calculation : eval="(amount / 100) * 20"
• 100$ volume discount : eval="If(amount > 1000,100,0)" (read: if amount is greater than 1000 then the result will be 100, otherwise 0)
• Number of boxes needed to carry that number of items : eval="Ceiling(items / boxsize)"
• Number of items you can add before another box is needed : eval="Reminder(items,boxside)"

Note: please take care that xreporter expressions are not that accurate when it comes to decimals. The default divide operator rounds the result, see http://issues.cocoondev.org/browse/XRP-115. Also consider that the available set of functions can be expanded implementing and using new ones. Please see http://outerthought.net/wqm/xreporter/en/expressions.html for an overview of xreportes expressions and IsNullFunction or StringFunction for examples of custom xreporter functions.

Version:

$Id: SimpleFormula.html 1304258 2012-03-23 10:09:27Z ilgrosso $

Field Summary

protected org.outerj.expression.Expression

formula

Fields inherited from class org.apache.cocoon.forms.formmodel.algorithms.AbstractBaseAlgorithm

triggers

Constructor Summary

SimpleFormula()

Method Summary

Object	calculate(Form form, Widget parent, Datatype datatype) Performs the actual calculation.
org.outerj.expression.Expression	getFormula()
boolean	isSuitableFor(Datatype dataType) Checks wether this algorithm is able to return the given datatype.
void	setFormula(org.outerj.expression.Expression formula)

Methods inherited from class org.apache.cocoon.forms.formmodel.algorithms.AbstractBaseAlgorithm

addTrigger, clearTriggers, contextualize, enableLogging, getContext, getLogger, getTriggerWidgets

Methods inherited from class java.lang.Object

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

Field Detail

formula

protected org.outerj.expression.Expression formula

Constructor Detail

SimpleFormula

public SimpleFormula()

Method Detail

isSuitableFor

public boolean isSuitableFor(Datatype dataType)

Description copied from interface: CalculatedFieldAlgorithm

Checks wether this algorithm is able to return the given datatype. For example, an arithmetic algorithm like sum should check that the given datatype is a number.

Parameters:

dataType - The target datatype.

Returns:

true if this algorithm can return a compatible value, false otherwise.

calculate

public Object calculate(Form form,
                        Widget parent,
                        Datatype datatype)

Description copied from interface: CalculatedFieldAlgorithm

Performs the actual calculation.

Parameters:

form - The form.

parent - The parent widget of the CalculatedField widget (may be the same as form)

datatype - The target datatype.

Returns:

the calculated value for the CalculatedField.

getFormula

public org.outerj.expression.Expression getFormula()

Returns:

Returns the formula.

setFormula

public void setFormula(org.outerj.expression.Expression formula)

Parameters:

formula - The formula to set.