A function can be used everywhere within the rule engine (condition expression, nls text). A predefined set of functions already exists.
To register the own function, open the "Preferences" dialog in the XUI Editor ("View" menu) and add a new function. After adding/modifying the functions, the XUI Edtior needs to be closed and started again. 
Implementing an own function means to extend the "com.jaxfront.core.jep.JaxfrontMathCommand" class . In the field "Implementation Class" enter the class name which extends this class. In the field "Category" add an existing category name or a new one. You will see all categories when using the formula engine. 
The class needs to extend the "com.jaxfront.core.jep.JaxfrontMathCommand" class:
Name | Description |
|---|---|
run(Stack) | Each function should use it's own run() method for evaluating the function. This includes popping off the parameters from the stack, and pushing the result back on the stack. |
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| Hinweis |
|---|
| See class com.jaxfront.demo.api.OwnFunction |
This function checks if the passed node values is a future date.
| Codeblock | ||||||
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public class OwnFunction extends SuperTypeNode { |
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public void run(Stack stack) throws ParseException { |
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// Check if stack is null |
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checkStack(stack); |
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Object param = null; |
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String xPath = null; |
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boolean isFutureDate = false; |
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if (curNumberOfParameters == 1) { |
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Type baseType = getCommunicator().getRootType(); |
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param = stack.pop(); |
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if (param == NULL._null) { |
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stack.push(NULL._null); |
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return; |
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} else if (param instanceof Type) { |
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baseType = (Type) param; |
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} else if (param instanceof String) { |
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xPath = (String) param; |
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} |
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Type resultType = null; |
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if (xPath != null && xPath.length() > 0) { |
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resultType = |
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TypePathExecuter.getInstance().getTypeForXPath( |
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baseType, |
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xPath.trim(), |
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true, |
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true); |
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} else |
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resultType = baseType; |
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if (resultType != null) { |
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if (resultType.isSimple()) { |
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SimpleType simpleType = (SimpleType)resultType; |
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String dateString = simpleType.getValue(); |
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if (dateString != null) { |
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try { |
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SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); |
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Date inputDate = format.parse(dateString); |
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Date currentDate = new Date(); |
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isFutureDate = inputDate.compareTo(currentDate) > 0; |
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} |
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catch (java.text.ParseException ex) { |
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//do nothing |
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} |
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} |
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} else { |
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throw new ParseException(this.getClass() + " Invalid target type (must be simple)"); |
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} |
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} |
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if (isFutureDate) { |
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stack.push(SuperTypeNode.isTrue); |
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} |
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else { |
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stack.push(SuperTypeNode.isFalse); |
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} |
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} else { |
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throw new ParseException(this.getClass() + " Invalid parameter type"); |
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} |
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} |
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} |