// overloaded UpdateCell, takes a cell as the parameter
private void UpdateCell(Cell cellToUpdate)
{
// remove old dependencies
RemoveDependencies(cellToUpdate);
// first check if the cell is empty
// i.e. the user deleted the text from the cell
if (string.IsNullOrEmpty(cellToUpdate.Text))
{
cellToUpdate.Value = "";
}
// if the text doesn't begin with an =
else if (cellToUpdate.Text[0] != '=')
{
double cellValue;
// if the cell contains a double
if (double.TryParse(cellToUpdate.Text, out cellValue))
{
// build the ExpTree to set the cell's variable
ExpTree userExpTree = new ExpTree(cellToUpdate.Text);
cellValue = userExpTree.Eval();
userExpTree.SetVar(cellToUpdate.Name, cellValue);
// update the value to the double
cellToUpdate.Value = cellValue.ToString();
}
else
{
// otherwise the value is just set to the text
cellToUpdate.Value = cellToUpdate.Text;
}
}
// need to evaluate an expression here
else
{
// parse the text to get the expression
string exp = cellToUpdate.Text.Substring(1);
// build an ExpTree, eval to add variables
ExpTree userExpTree = new ExpTree(exp);
userExpTree.Eval();
// get the variable names
string[] varNames = userExpTree.GetVarNames();
// loop through each variable name in the array
foreach (string variable in varNames)
{
// get the cell and add its value to the dictionary
double value = 0.0;
Cell relevantCell = GetCell(variable);
// try to parse out the double
double.TryParse(relevantCell.Value, out value);
// set the variable
userExpTree.SetVar(variable, value);
}
// set the value to the computed value of the ExpTree
cellToUpdate.Value = userExpTree.Eval().ToString();
// add the dependencies
AddDependencies(cellToUpdate, varNames);
}
// if there are cells that depend on the one we just updated
if (m_dependencies.ContainsKey(cellToUpdate))
{
// update all dependent cells
UpdateDependencies(cellToUpdate);
}
// and notify subscribers that the cell property changed
// need to pass the sender which is the cell
// passing the this reference would pass the spreadsheet
CellPropertyChanged(cellToUpdate, new PropertyChangedEventArgs("CellChanged"));
}
// overloaded UpdateCell, takes a cell as the parameter
private void UpdateCell(Cell cellToUpdate)
{
// remove old dependencies
RemoveDependencies(cellToUpdate);
// first check if the cell is empty
// i.e. the user deleted the text from the cell
if (string.IsNullOrEmpty(cellToUpdate.Text))
{
cellToUpdate.Value = "";
}
// if the text doesn't begin with an =
else if (cellToUpdate.Text[0] != '=')
{
double cellValue;
// if the cell contains a double
if (double.TryParse(cellToUpdate.Text, out cellValue))
{
// build the ExpTree to set the cell's variable
ExpTree userExpTree = new ExpTree(cellToUpdate.Text);
cellValue = userExpTree.Eval();
userExpTree.SetVar(cellToUpdate.Name, cellValue);
// update the value to the double
cellToUpdate.Value = cellValue.ToString();
}
else
{
// otherwise the value is just set to the text
cellToUpdate.Value = cellToUpdate.Text;
}
}
// need to evaluate an expression here
else
{
// flag to check for errors
bool errors = false;
// parse the text to get the expression
string exp = cellToUpdate.Text.Substring(1);
// build an ExpTree, eval to add variables
ExpTree userExpTree = new ExpTree(exp);
userExpTree.Eval();
// get the variable names
string[] varNames = userExpTree.GetVarNames();
// loop through each variable name in the array
foreach (string variable in varNames)
{
// get the cell and add its value to the dictionary
double value = 0.0;
Cell relevantCell = GetCell(variable);
// check for valid cells
// CASE ONE: BAD REFERENCE
if (relevantCell == null)
{
// display that the cell has a bad reference and notify subscribers
cellToUpdate.Value = "!(bad reference)";
CellPropertyChanged(cellToUpdate, new PropertyChangedEventArgs("CellChanged"));
// set the error flag to true
errors = true;
}
// CASE TWO: SELF-REFERENCE
else if (cellToUpdate.Name == variable)
{
// display that the cell has a self-reference and notify subscribers
cellToUpdate.Value = "!(self reference)";
CellPropertyChanged(cellToUpdate, new PropertyChangedEventArgs("CellChanged"));
// set the error flag to true
errors = true;
}
// if there's an error, get out of the function
if (errors == true)
{
// if there are cells that depend on the one we just updated
if (m_dependencies.ContainsKey(cellToUpdate))
{
// update all dependent cells
UpdateDependencies(cellToUpdate);
}
return;
}
// try to parse out the double
double.TryParse(relevantCell.Value, out value);
// set the variable
userExpTree.SetVar(variable, value);
// add the cell to the HashSet to check for circular references
this.visitedCells.Add(relevantCell);
}
// set the value to the computed value of the ExpTree
cellToUpdate.Value = userExpTree.Eval().ToString();
// add the dependencies
AddDependencies(cellToUpdate, varNames);
// check for circular references
if (CheckForCircularReferences(cellToUpdate))
{
// display that the cell has a circular-reference and notify subscribers
cellToUpdate.Value = "!(circular reference)";
CellPropertyChanged(cellToUpdate, new PropertyChangedEventArgs("CellChanged"));
// set the error flag to true
errors = true;
}
// if there's an error, get out of the function
if (errors == true)
{
return;
}
}
// if there are cells that depend on the one we just updated
if (m_dependencies.ContainsKey(cellToUpdate))
{
// update all dependent cells
UpdateDependencies(cellToUpdate);
}
// and notify subscribers that the cell property changed
// need to pass the sender which is the cell
// passing the this reference would pass the spreadsheet
CellPropertyChanged(cellToUpdate, new PropertyChangedEventArgs("CellChanged"));
// clear the visited cells HashSet at a successful cell change
this.visitedCells.Clear();
}