public void OnPropertyChanged(object sender, PropertyChangedEventArgs e) // For each fired event property changed
{
if (e.PropertyName == "Text") // Text changed
{
CellInstance currentCell = sender as CellInstance;
RemoveReferences(currentCell.Name);
if (!string.IsNullOrEmpty(currentCell.Text) && currentCell.Text.StartsWith("=") && currentCell.Text.Length > 1)
{
ExpTree expression = new ExpTree();
expression.ExpressionString = currentCell.Text.Substring(1);
AddReferences(currentCell.Name, expression.GetVar());
}
EvalCell(currentCell);
}
if (e.PropertyName == "BGColor") // Background Color changed
{
CellPropertyChanged(sender, new PropertyChangedEventArgs("BGColor"));
}
}
public void EvalCell(Cell cell) // Evaluate a cell
{
CellInstance instance = cell as CellInstance;
if (string.IsNullOrEmpty(cell.Text))
{
instance.SetValue(""); //set to nothing for default
CellPropertyChanged(cell, new PropertyChangedEventArgs("Value")); // if value changed
}
else if (cell.Text[0] == '=' && cell.Text.Length > 1) // for an equation
{
bool error = false;
ExpTree expression = new ExpTree();
expression.ExpressionString = cell.Text.Substring(1);
List <string> expressionVar = expression.GetVar();
foreach (string variable in expressionVar) // check for errors
{
if (variable == cell.Name) // self reference
{
instance.SetValue("!(self reference)");
error = true;
break;
}
if (GetCell(variable) == null) // cell does not exist
{
instance.SetValue("!(bad reference)");
error = true;
break;
}
if (IsCircularReference(variable, cell.Name)) // circular reference
{
instance.SetValue("!(circular reference)");
error = true;
break;
}
Cell variableCell = GetCell(variable);
double variableValue;
if (string.IsNullOrEmpty(variableCell.Value)) // check for empty value
{
expression.SetVar(variable, 0);
}
else if (!double.TryParse(variableCell.Value, out variableValue))
{
expression.SetVar(variable, 0);
}
else
{
expression.SetVar(variable, variableValue);
}
}
if (error) // for errors
{
CellPropertyChanged(cell, new PropertyChangedEventArgs("Value"));
return;
}
//at this point, the variables are set
instance.SetValue(expression.Eval().ToString()); // Evaluate expression and set value of Cell
CellPropertyChanged(cell, new PropertyChangedEventArgs("Value"));
}
else // if not an expression
{
instance.SetValue(cell.Text); // chage text of cell
CellPropertyChanged(cell, new PropertyChangedEventArgs("Value"));
}
if (_references.ContainsKey(instance.Name)) // Evaluate referenced cells
{
foreach (string cellName in _references[instance.Name])
{
EvalCell(GetCell(cellName));
}
}
}
