Implement Custom Calculation Engine to extend the Default Calculation Engine of Aspose.Cells with 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
#include <iostream>
#include <cwctype>
#include "Aspose.Cells.h"
#include <chrono>
using namespace Aspose::Cells;
class CustomEngine : public AbstractCalculationEngine
{
public:
void Calculate(CalculationData& data) override
{
U16String funcName = data.GetFunctionName();
std::u16string upperName;
for (int i = 0; i < funcName.GetLength(); ++i)
{
upperName.push_back(std::towupper(funcName[i]));
}
if (upperName == u"TODAY")
{
auto now = std::chrono::system_clock::now();
std::time_t now_time = std::chrono::system_clock::to_time_t(now);
std::tm local_tm;
#ifdef _WIN32
localtime_s(&local_tm, &now_time);
#else
localtime_r(&now_time, &local_tm);
#endif
Date today{ local_tm.tm_year + 1900, local_tm.tm_mon + 1, local_tm.tm_mday };
data.SetCalculatedValue(Date{ today.year, today.month, today.day + 1 });
}
}
bool GetProcessBuiltInFunctions() override { return true; }
};
class ImplementCustomCalculationEngine
{
public:
static void Run()
{
Workbook workbook;
Worksheet sheet = workbook.GetWorksheets().Get(0);
Cell a1 = sheet.GetCells().Get(u"A1");
Style style = a1.GetStyle();
style.SetNumber(14);
a1.SetStyle(style);
a1.SetFormula(u"=TODAY()");
workbook.CalculateFormula();
std::cout << "The value of A1 with default calculation engine: " << a1.GetStringValue().ToUtf8() << std::endl;
CustomEngine engine;
CalculationOptions opts;
opts.SetCustomEngine(&engine);
workbook.CalculateFormula(opts);
std::cout << "The value of A1 with custom calculation engine: " << a1.GetStringValue().ToUtf8() << std::endl;
std::cout << "Press any key to continue..." << std::endl;
std::cin.get();
}
};
int main()
{
Aspose::Cells::Startup();
ImplementCustomCalculationEngine::Run();
Aspose::Cells::Cleanup();
return 0;
}
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.