//evaluate cell accepts a cell as an argument and checks to see if it is an expression
// or just a string. if it begins with '=' it is an expression and will be evaluated as such.
//otherwise the text will just be reassigned.
private void EvaluateCell(Cell cell)
{
ss_cell c = cell as ss_cell;
//cell represents an expression
if (c.text[0] == '=')
{
//chop off '='
string expression = c.text.Substring(1);
string[] ABC = { "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
//creates an expression tree based off of the expression
ExpTree exp = new ExpTree(expression);
//get a list of the variables
string[] vars = exp.getVars();
foreach (string variableName in vars)
{
if (GetCell(variableName) == null) //does not reference an actual cell
{
break;
}
setVariable(exp, variableName);
}
c.SetValue(exp.Eval().ToString());
CellPropertyChanged(cell, new PropertyChangedEventArgs("value"));
//trigger cellpropertychanged
CellPropertyChanged(cell, new PropertyChangedEventArgs("text"));
}
//not an expression
else
{
c.SetValue(c.text);
CellPropertyChanged(cell, new PropertyChangedEventArgs("value"));
}
if (DependencyDict.ContainsKey(c.name))
{
foreach (string dependentCell in DependencyDict[c.name])
{
EvaluateCell(GetCell(dependentCell));
}
}
//else
//{
// //just set the value to the text of the node passed in
// c.SetValue(c.text);
// //event trigger.
// CellPropertyChanged(cell, new PropertyChangedEventArgs("value"));
//}
}
//constructor accepts a row index and a column index
public SS(int row, int col)
{
Cells = new Cell[row, col];
DependencyDict = new Dictionary <string, HashSet <string> >();
for (int i = 0; i < row; i++)
{
for (int j = 0; j < col; j++)
{
Cells[i, j] = new ss_cell(i, j);
Cells[i, j].PropertyChanged += OnPropertyChanged; //subscribe to PropertyChanged event
}
}
}
//OnPropertyChanged is what is happening when a cell's PropertyChanged event is triggered.
//it simply evaluates the cell and sends the update to the next layer.
private void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "text")
{
ss_cell c = sender as ss_cell;
RemoveDependencies(c.name);//remove dependencies here
if (c.text != "" && c.text[0] == '=')
{
ExpTree exp = new ExpTree(c.text.Substring(1));
MakeDependencies(c.name, exp.getVars());
}
EvaluateCell(sender as Cell);
}
}
