Implement Custom Calculation Engine to extend the Default Calculation Engine of Aspose.Cells with JavaScript via C++
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.
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
<!DOCTYPE html>
<html>
<head>
<title>Custom Calculation Engine Example</title>
</head>
<body>
<h1>Custom Calculation Engine Example</h1>
<input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
<button id="runExample" disabled>Run Example</button>
<a id="downloadLink" style="display: none;">Download Result</a>
<div id="result"></div>
</body>
<script src="aspose.cells.js.min.js"></script>
<script type="text/javascript">
const { Workbook, SaveFormat, CalculationOptions, CellsHelper } = AsposeCells;
AsposeCells.onReady({
license: "/lic/aspose.cells.enc",
fontPath: "/fonts/",
fontList: [
"arial.ttf",
"NotoSansSC-Regular.ttf"
]
}).then(() => {
console.log("Aspose.Cells initialized");
document.getElementById('runExample').disabled = false;
});
// Create a new class derived from AbstractCalculationEngine
class CustomEngine extends AsposeCells.AbstractCalculationEngine {
constructor() {
super();
// Indicate processing built-in functions
this.processBuiltInFunctions = true;
}
// Override the Calculate method with custom logic
calculate(data) {
// Check the formula name and change the implementation
if (data.functionName.toUpperCase() === "TODAY") {
// Assign the CalculationData.CalculatedValue: add one day offset for the date
data.calculatedValue = CellsHelper.getDoubleFromDateTime(new Date(), false) + 1.0;
}
}
}
class ImplementCustomCalculationEngine {
static run() {
// Create an instance of Workbook
const workbook = new Workbook();
// Access first Worksheet from the collection
const sheet = workbook.worksheets.get(0);
// Access Cell A1 and put a formula to sum values of B1 to B2
const a1 = sheet.cells.get("A1");
const style = a1.style;
style.number = 14;
a1.style = style;
a1.formula = "=TODAY()";
// Calculate all formulas in the Workbook
workbook.calculateFormula();
// The result of A1 with default calculation engine
console.log("The value of A1 with default calculation engine: " + a1.stringValue);
// Create an instance of CustomEngine
const engine = new CustomEngine();
// Create an instance of CalculationOptions
const 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 with custom calculation engine
console.log("The value of A1 with custom calculation engine: " + a1.stringValue);
console.log("Press any key to continue...");
document.getElementById('result').innerHTML = '<p style="color: green;">Calculation completed. Check console for output.</p>';
}
}
document.getElementById('runExample').addEventListener('click', () => {
ImplementCustomCalculationEngine.run();
});
</script>
</html>
Result
Please check the console output of the above sample code; the value (date time) of A1 with the custom engine should be one day later than the result without the custom engine.