// PropertyChanged event for SpreadSheet.
// This method is where all the meat is for when a cell gets an input by the user.
// The purpose of it is to determine if a user entered an formula or a value.
// If it's a formula it uses the ExpTree to calculate the value, and set the cells value to that.
// If the user doesn't enter a formula, it sets that cell value and text to what the user entered.
// -----------------------------------------------------------------------------
// It's good to point out also how the there is a check to see if the input is valid,
// if it's invalid the cell will display "#REF",
// Then after the cell gets updated, all the dictionaries get updated accordingly.
private void SpreadSheetCell_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
var currentCell = sender as SpreadsheetCell;
ExpTree tree = new ExpTree(variables);
List <string> multiDependencies = new List <string>();
// Check if input is valid
if (!IsValidInput(currentCell))
{
currentCell.SetValue("#REF");
return;
}
// If the user entered a formula
if (currentCell.Text != null && currentCell.Text[0] == '=')
{
tree.SetExpression(currentCell.Text.Substring(1));
currentCell.SetExpression(currentCell.Text.Substring(1));
currentCell.SetValue(tree.Eval().ToString());
// Gets the new dependencies from the tree,
// and in a loop updates the dependency dictionary
multiDependencies = tree.GetDependencies();
foreach (string s in multiDependencies)
{
SpreadsheetCell myCell = GetCell(s);
if (!dependencies.ContainsKey(myCell))
{
dependencies.Add(myCell, new List <SpreadsheetCell>());
}
dependencies[myCell].Add(currentCell);
}
}
// If user enters a value
else
{
// Set value of the cell
currentCell.SetValue(currentCell.Text);
// Set the expression of that cell to null
currentCell.SetExpression(string.Empty);
RemoveDependencies(currentCell);
}
UpdateVariables(currentCell);
if (CellPropertyChanged != null)
{
CellPropertyChanged(sender, e);
}
UpdateDependencies(currentCell, tree);
}
// The purpose of this method is to update the dependencies in the spreadsheet
// after a cell gets messed with. It iterates through a list of dependencies (from inside the dependencies dictionary)
// and recursively updates all cells that are dependent on that specific cell
public void UpdateDependencies(SpreadsheetCell currentCell, ExpTree tree)
{
// Check if that cell has dependencies
if (dependencies.ContainsKey(currentCell))
{
// iterate through the list inside dependencies dictionary
foreach (SpreadsheetCell c in dependencies[currentCell])
{
// Updates the tree's expression
tree.SetExpression(c.GetExpression());
// Sets the new value to the new Eval from the tree
c.SetValue(tree.Eval().ToString());
CellPropertyChanged(c, new PropertyChangedEventArgs("Value"));
// Update variables dictionary
UpdateVariables(c);
UpdateDependencies(c, tree);
}
}
}