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

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

All Implemented Interfaces:

Contextualizable, LogEnabled, CalculatedFieldAlgorithm

public class RepeatedFormula
extends SimpleFormula

An xreporter Expression based algorithm that repeats the formula on a set of fields.

The specified formula will be applied iterating on the specified widgets. The final result will be the result of the last iteration. From inside the formula you can access this two extra variables :

formulaResult

The result of the previous iteration, or the result of the initial result if this is the first iteration.

formulaCurrent

The value of the current trigger widget.

The initial result is evaluated before starting the iteration, and its value is used as a formulaResult for the first iteration.

It's possible to define nearly every cyclic arithmetic operation with this algorithm, for example :

Sum

initial-result="0" formula="formulaResult + formulaCurrent"

Multiplication

initial-result="1" formula="formulaResult * formulaCurrent"

More over, thru the use of advanced xreporter syntax it's possible to quickly implement also complex algorithms:

• Count all items with a price higher than 100 : eval="formulaResult + If(price > 100, 1, 0)" (read : the result is the previous result plus one if price is over 100, 0 if price is less than 100)
• Obtain a sum of all movements, wether they are positive or negative amount movements : eval="formulaResult + Abs(amount)"
• Count how many slots are empty in the 10 items box you are using for packaging : eval="formulaResult + Reminder(items, 10)"

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

Field Summary

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

formula

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

triggers

Constructor Summary

RepeatedFormula()

Method Summary

Object	calculate(Form form, Widget parent, Datatype datatype) Performs the actual calculation.
org.outerj.expression.Expression	getInitialResult()
String	getRepeatOn()
void	setInitialResult(org.outerj.expression.Expression initialResult)
void	setRepeatOn(String iterateOn)

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

getFormula, isSuitableFor, setFormula

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

Constructor Detail

RepeatedFormula

public RepeatedFormula()

Method Detail

calculate

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

Description copied from interface: CalculatedFieldAlgorithm

Performs the actual calculation.

Specified by:

calculate in interface CalculatedFieldAlgorithm

Overrides:

calculate in class SimpleFormula

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.

getInitialResult

public org.outerj.expression.Expression getInitialResult()

Returns:

Returns the initialResult.

setInitialResult

public void setInitialResult(org.outerj.expression.Expression initialResult)

Parameters:

initialResult - The initialResult to set.

getRepeatOn

public String getRepeatOn()

Returns:

Returns the iterateOn.

setRepeatOn

public void setRepeatOn(String iterateOn)

Parameters:

iterateOn - The iterateOn to set.