Implement Custom Calculation Engine to extend the Default Calculation Engine of Aspose.Cells

Aspose.Cells has a powerful calculation engine that can calculate almost all of the Microsoft Excel formulas. Despite this, it also allows you to extend the default calculation engine which provides you greater power and flexibility.

The following property and classes are used in implementing this feature.

• CalculationOptions.CustomEngine
• AbstractCalculationEngine
• CalculationData

Implement Custom Calculation Engine

The following code implements the Custom Calculation Engine. It implements the interface AbstractCalculationEngine which has only one method calculate(CalculationData data). This method is called against all of your formulas. Inside this method, we capture the SUM formula and increases its value by 30. So if the Aspose.Cells calculated value is 20, then our custom engine will make it 50 by adding 30.

// For complete examples and data files, please go to https://github.com/aspose-cells/Aspose.Cells-for-Java
public class CustomEngine extends AbstractCalculationEngine {
	public void calculate(CalculationData data) {
		if (data.getFunctionName().toUpperCase().equals("TODAY")) {
			data.setCalculatedValue(CellsHelper.getDoubleFromDateTime(DateTime.getNow(), false) + 1.0);
		}
	}
	public getProcessBuiltInFunctions() { return true; }
}

public static void main(String[] args) throws Exception {

	// The path to the documents directory.
	String dataDir = Utils.getDataDir(ImplementCustomCalculationEngine.class);

	Workbook workbook = new Workbook();

	Worksheet sheet = workbook.getWorksheets().get(0);

	Cell a1 = sheet.getCells().get("A1");
    Style style = cell.getStyle();
    style.setNumber(14);
    cell.setStyle(style);
    
	a1.setFormula("=TODAY()");

	// Without Custom Engine, the value of cell A1 will be 20
	workbook.calculateFormula();

	System.out.println("Without Custom Engine Value of A1: " + a1.getStringValue());

	// With Custom Engine, the value of cell A1 will be 50

	CalculationOptions opts = new CalculationOptions();
	opts.setCustomEngine(new CustomEngine());

	workbook.calculateFormula(opts);

	System.out.println("With Custom Engine Value of A1: " + a1.getStringValue());

}

Console Output

Here is the console output of the above sample code.

 Without Custom Engine Value of A1: 20

With Custom Engine Value of A1: 50

Related Article

• Direct calculation of custom function without writing it in a worksheet