DSL Description Dutch

Rule Engine DSL description - Dutch

A description of the many features of the Rule Engine DSL. This page explains the Dutch DSL. Apart from the DSL terms, it is written in English.

Introduction

###Basic setup A calculation follows a pre-defined pre-defined structure.

Gegeven (Condition) Bereken Fact is (Evaluation)

It starts with the word Gegeven followed by a DslCondition (explained below) between brackets. Next is the word Bereken which is followed by the outputFact of the calculation. Facts are usually defined in a Glossary. Brackets are not needed here. Finally there is the is word, after which comes either an DslEvaluation or a Subberekening. Brackets are often, but not always, needed. It is advised to always use them, to not run into any problems.

Chaining calculations

It is possible to chain several calculations that share the same Condition. Do this uses the en word after the evaluation.

Gegeven (...) Bereken ... is (...) en
... is (...)

Berekening class

Calculations have to be inside a Berekening class. The easiest way to do this is to create a class of your own:

class MyBerekening extends Berekening (
  Gegeven (...) Bereken ... is (...)
  ,
  Gegeven (...) Bereken ... is (...)
)

The Condition

After the Gegeven word you have to define a DslCondition. This condition will determine whether the calculation will trigger and the resulting Fact calculated¹. A DslCondition starts with a Fact followed by a conditional operator and another Fact or a constant value. Conditions can be chained using en or of. These combinations will be evaluated from left to right. When combining en and of, it is best to use brackets to group conditions. These will be respected when evaluating and grouping behaves like expected from mathematics.

Some examples of Conditions:

Gegeven (Fact1 is Fact2 of Fact1 > 0)
Gegeven (Fact1 is true of (Fact2 >= 0 en Fact3 <= 5))

Altijd

Because it is mandatory to start with a condition, there is a special condition that will always evaluate to true. This ensures that the calculation is executed without any extra condition. This special condition can be used by using the word altijd as seen here

Gegeven (altijd)

##The Evaluation

An evaluation is used to assign a value to the Fact defined as output (the fact given after the Bereken) After the is word you have to define a DslEvaluation or a SubCalculation.

###DslEvaluation

SubCalculation

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1: The Dsl does not only look to the Condition to see if a rule can trigger. The Dsl also ensures that the (Input)Facts needed to calculate the outcome are added as a condition to the Engine. See the Evaluation section for more details