private bool ContainsCircularRefRec(SheetCell cell, HashSet <SheetCell> curChain)
{
if (curChain.Contains(cell))
{
return(true);
}
if (Refs.ContainsKey(cell) && Refs[cell].Count > 0)
{
curChain.Add(cell);
foreach (var cellRef in Refs[cell])
{
// create a duplicate HashSet for every new possible walk on the graph of cells.
// this is so that cells that reference multiple values that don't contain
// crefs wont cause false positives
if (ContainsCircularRefRec(cellRef, new HashSet <SheetCell>(curChain)))
{
return(true);
}
}
}
return(false);
}
private void UpdateRefs(SheetCell cell)
{
if (!Refs.ContainsKey(cell))
{
return;
}
// recompute the values and update Vars dict
foreach (var refCell in Refs[cell])
{
if (refCell.InvalidExp)
{
continue;
}
var res = refCell.ETree.Eval();
Vars[refCell.Name] = res;
refCell.SetValue(res.ToString());
CellPropertyChanged(refCell, new PropertyChangedEventArgs("Value"));
// recursively update ref ref calls etc
UpdateRefs(refCell);
}
}
// called whenever a cell changes so that we can dispatch another event as well as
// check to see if we need to look up the value in another cell
private void CellChanged(object sender, PropertyChangedEventArgs e)
{
var cell = sender as SheetCell;
if (e.PropertyName == "Color")
{
CellPropertyChanged(cell, new PropertyChangedEventArgs("Color"));
return;
}
// reset expression validity when it changes
// if its still invalid it will get set back
// to true
cell.InvalidExp = false;
// handle raw numbers
double val;
if (double.TryParse(cell.Text, out val))
{
foreach (var old in cell.Deps)
{
Refs[Name2Cell(old)].Remove(cell);
}
cell.Deps.Clear();
Vars[cell.Name] = val;
cell.SetValue(val.ToString());
}
else if (cell.Text != null && cell.Text.Length > 0 && cell.Text[0] == '=')
{
cell.ETree = new ExpTree(cell.Text.Substring(1), Vars);
double res = cell.ETree.Eval();
var newDeps = cell.ETree.GetExpLocals();
// cell expression variables contain reference to the cell itself
if (newDeps.FirstOrDefault(dep => dep == cell.Name) != null)
{
cell.SetValue("!(self reference)");
cell.InvalidExp = true;
}
// one of the cell expression variables is invalid
else if (newDeps.FirstOrDefault(dep => Name2Cell(dep) == null) != null)
{
cell.SetValue("!(bad reference)");
cell.InvalidExp = true;
}
// chain of cell exp vars contains a circular reference
else if (newDeps.ToList().FirstOrDefault(p => ContainsCircularRef(cell, Name2Cell(p))) != null)
{
cell.SetValue("!(circ reference)");
cell.InvalidExp = true;
}
else
{
Vars[cell.Name] = res;
// remove dependencies that arent needed anymore
foreach (var old in cell.Deps.Except(newDeps))
{
Refs[Name2Cell(old)].Remove(cell);
}
cell.Deps = newDeps;
// add current cell to each set corresponding to one of the current cell's
// dependencies
foreach (var dep in cell.Deps)
{
var rcell = Name2Cell(dep);
if (!Refs.ContainsKey(rcell))
{
Refs.Add(rcell, new HashSet <SheetCell>());
}
Refs[rcell].Add(cell);
}
cell.SetValue(res.ToString());
}
}
else
{
// remove previous dependencies when directly setting text
foreach (var old in cell.Deps)
{
Refs[Name2Cell(old)].Remove(cell);
}
// changing cells that have dependencies from numerical to be strings
// defaults the cells value to 0 so that all dependencies get updated with
// the 0 value
Vars[cell.Name] = 0;
cell.SetValue(cell.Text);
}
// now update all dependencies
UpdateRefs(cell);
CellPropertyChanged((sender as SheetCell), new PropertyChangedEventArgs("Value"));
}
