/// <summary>
/// This is a helper method that looks up the value of a given cell
/// its main use is when cells are created. Here when in the creation of a cell
/// we want to immidiately use lookup as the delegete for the evaluator method in formula
/// </summary>
/// <returns></returns>
private double lookup(string nameOfCell)
{
//name is converted to upper
nameOfCell = nameOfCell.ToUpper();
if (!cellDictionary.ContainsKey(nameOfCell))
{
throw new FormulaEvaluationException("The variable could not be found in the spreadsheet");
}
Cell tempCell = cellDictionary[nameOfCell];
if (tempCell.GetValue() is double)
{
return((double)tempCell.GetValue());
}
else
{
throw new FormulaEvaluationException("Lookup could not be properly performed.");
}
}
public override object GetCellValue(string name)
{
// Normalize our cell name
string cellName = Normalize(name);
// If name is null or invalid.
CheckCellName(cellName);
if (Cells.ContainsKey(cellName))
{
Cell temp = Cells[cellName];
return(temp.GetValue());
}
return("");
}
// Private helper methods for Spreadsheet
/// <summary>
/// Private helper method that uses our dictionary "Cells" in order to
/// lookup a cell's value for evaluation.
/// This method will throw an arguement exception if:
/// - A Cell is empty (value is empty string)
/// - A cell's value is a string / formula error
/// This in turn will cause an evaluation in the Formula Class of this cell
/// to result in a return of a FormulaError.
/// </summary>
/// <param name="name">Cell Name</param>
/// <returns>Cell's double value.</returns>
private double lookup(string name)
{
// Looking up a cell that hasnt been added yet, add an empty one.
if (!Cells.ContainsKey(name))
{
Cells.Add(name, new Cell(name, ""));
}
Cell cell = Cells[name];
object value = cell.GetValue();
// We have a string or FormulaError as the value of our cell.
if (value is string || value is FormulaError)
{
throw new ArgumentException();
}
// Else we know our cell value is a double and we can return it as such.
return((double)value);
}