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

Implement Custom Calculation Engine

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

The following code implements the Custom Calculation Engine. It implements the interface AbstractCalculationEngine which has a Calculate(CalculationData data) method. This method is called against all of your formulas. Inside this method, we capture the TODAY function and add one day to the system date. So if the current date is 27/07/2023, then the custom engine will calculate TODAY() as 28/07/2023.

Programming Sample

// For complete examples and data files, please go to https://github.com/aspose-cells/Aspose.Cells-for-.NET
// Create a new class derived from AbstractCalculationEngine
class CustomEngine : AbstractCalculationEngine
{
    // Override the Calculate method with custom logic
    public override void Calculate(CalculationData data)
    {
        // Check the forumla name and change the implementation
        if (data.FunctionName.ToUpper() == "TODAY")
        {
            // Assign the CalculationData.CalculatedValue: add one day offset for the date
            data.CalculatedValue = CellsHelper.GetDoubleFromDateTime(DateTime.Today, false) + 1.0;
        }
    }
    public override bool ProcessBuiltInFunctions { get { return true; } }
}

class ImplementCustomCalculationEngine
{
    public static void Run()
    {
        // Create an instance of Workbook
        Workbook workbook = new Workbook();

        // Access first Worksheet from the collection
        Worksheet sheet = workbook.Worksheets[0];

        // Access Cell A1 and put a formula to sum values of B1 to B2
        Cell a1 = sheet.Cells["A1"];
        Style style = a1.GetStyle();
        style.Number = 14;
        a1.SetStyle(style);
        
        a1.Formula = "=TODAY()";

        // Calculate all formulas in the Workbook 
        workbook.CalculateFormula();

        // The result of A1 should be 20 as per default calculation engine
        Console.WriteLine("The value of A1 with default calculation engine: " + a1.StringValue);

        // Create an instance of CustomEngine
        CustomEngine engine = new CustomEngine();

        // Create an instance of CalculationOptions
        CalculationOptions opts = new CalculationOptions();

        // Assign the CalculationOptions.CustomEngine property to the instance of CustomEngine
        opts.CustomEngine = engine;

        // Recalculate all formulas in Workbook using the custom calculation engine
        workbook.CalculateFormula(opts);

        // The result of A1 will be 50 as per custom calculation engine
        Console.WriteLine("The value of A1 with custom calculation engine: " + a1.StringValue);

        Console.WriteLine("Press any key to continue...");
        Console.ReadKey();
    }
}

Result

Please check the console output of the above sample code, the value(date time) of A1 with custom engine should be one day later than the result without custom engine.

Related Article

Direct calculation of custom function without writing it in a worksheet