/// <summary>
/// Interpret the expression contained by a cell, and return its value
/// </summary>
/// <param name="expression">the expression to interpret</param>
/// <param name="cellToInterpret">the cell containing the expression</param>
/// <returns>the interpreted value</returns>
private string InterpretExpression(string expression, ref SpreadsheetCell cellToInterpret)
{
var expTree = new ExpTree(expression);
string value = "";
var singleCellExpression = (SpreadsheetCell)GetCellFromStr(expression);
if (null != singleCellExpression && singleCellExpression != cellToInterpret)
{
if (VerifyNoCycles(cellToInterpret, singleCellExpression))
{
value = String.IsNullOrEmpty(singleCellExpression.Value) ? "0" : singleCellExpression.Value;
Subscribe(cellToInterpret, singleCellExpression);
}
else
{
value = "#REF!";
}
}
else if (expTree.IsValidExpression())
{
if (AssignExpTreeVars(ref cellToInterpret, ref expTree))
{
value = expTree.Eval().ToString();
}
else
{
value = "#REF!";
}
}
else
{
value = "#VALUE!";
}
return(value);
}
