如何直接在 POI Apache/NPOI 中评估公式/参数的字符串表示形式

Question

I want to convert some spreadsheets which contain references to a plugin-defined function which we are trying to remove. There is a method to convert this which works in VBA by using SUMIFS and generating a table

I am at the step where I have parsed the formulas and extracted the parameters used for the function (done by bracket counting). I have hit a snag. How do I get NPOI/POI Apache to evaluate the things. It seems to demand everything be done inside a cell. This isn't possible in this scenario (since these are parameters not cell formulas, so they don't have a cell in which to evaluate them).

There is the OperandResolver class which seems to be along the right lines, but it wants a ValueEval type as its input which I can't figure out at all. Currently I can only get the parameters as strings. Like "A1", "0.9", "SomeOtherFunction(...)" etc. Those are what I have.

Basically I need something like

pseudocode:    
var result = Evaluate_Formula_String(string formula, var Contextual_Information_eg_current_Worksheet)

Where the result would contain either a string or something easily converted into a string.

Answer 1

The function you need seems to be simply Application.Evaluate. It takes a string and evaluates it.

Reference page: https://docs.microsoft.com/en-us/office/vba/api/excel.application.evaluate