/// <summary>
/// Sets a variable name and value for dictionary of ExpressionTree
/// </summary>
/// <param name="expressionTree">ExpressionTree being evaluated</param>
/// <param name="varName">Name of the variable</param>
private void SetCellVariable(SpreadsheetEngine.ExpressionTree expressionTree, string varName)
{
SpreadsheetCell cell = this.GetCell(varName);
if (double.TryParse(cell.CellValue, out double cellValue))
{
expressionTree.SetVariable(varName, cellValue);
}
else
{
expressionTree.SetVariable(varName, 0.0);
}
}
/// <summary>
/// Runs the ExpressionTree Demo
/// </summary>
public void MainMenu()
{
// Local Variables
string userExpression = "A1+B1+C1";
string userInput = "";
string varName = "";
double varValue = 0;
do
{
// Show Menu
Console.WriteLine("Menu (current expression = \"" + userExpression + "\")");
Console.WriteLine("1. Enter a new expression");
Console.WriteLine("2. Set a variable value");
Console.WriteLine("3. Evaluate tree");
Console.WriteLine("4. Quit");
// Get User Option
userInput = Console.ReadLine().ToString();
switch (userInput)
{
case "1":
Console.WriteLine("Enter a new expression: ");
userExpression = Console.ReadLine();
userExpressionTree = new SpreadsheetEngine.ExpressionTree(userExpression);
break;
case "2":
Console.WriteLine("Enter a variable name: ");
varName = Console.ReadLine();
Console.WriteLine("Enter a variable value: ");
varValue = Convert.ToDouble(Console.ReadLine());
userExpressionTree.SetVariable(varName, varValue);
break;
case "3":
Console.WriteLine(userExpressionTree.Evaluate());
break;
default:
break;
}
} while (userInput != "4"); // Exit if User enters "4"
}
/// <summary>
/// Evaluates Cell's Value based on Entered Text
/// </summary>
/// <param name="cell"></param>
private void EvaluateSpreadsheetCell(SpreadsheetCell cell)
{
if (cell is SpreadsheetCell currentCell && currentCell != null)
{
// Empty Cell
if (string.IsNullOrEmpty(currentCell.CellText))
{
currentCell.CellValue = string.Empty;
this.OnPropertyChanged(cell, "CellChanged");
}
// Non-Formula
else if (currentCell.CellText[0] != '=')
{
currentCell.CellValue = currentCell.CellText;
this.OnPropertyChanged(cell, "CellChanged");
}
// Formula
else
{
// Build the Expression Tree Based on Cell Text
SpreadsheetEngine.ExpressionTree expressionTree = new SpreadsheetEngine.ExpressionTree(currentCell.CellText.Substring(1));
// Get the Variable Names from the Expression Tree
string[] variableNames = expressionTree.GetVariableNames();
foreach (string variable in variableNames)
{
SpreadsheetCell variableCell = this.GetCell(variable);
// Check for Bad / Self References
if (!CheckValidReference(currentCell, variableCell) || CheckSelfReference(currentCell, variableCell))
{
return;
}
// Adjust Variable Values
if (variableCell.CellValue != string.Empty && !variableCell.CellValue.Contains(" "))
{
expressionTree.SetVariable(variable, Convert.ToDouble(variableCell.CellValue));
}
else
{
// Set Default Variable Value to 0.0
expressionTree.SetVariable(variable, 0.0);
}
}
// Mark Cells Dependent on the One Being Changed
AddCellDependency(currentCell, variableNames);
// Check Dependent Cells for Circular References
foreach (string variable in variableNames)
{
SpreadsheetCell variableCell = this.GetCell(variable);
if (CheckCircularReference(variableCell, currentCell))
{
currentCell.CellValue = "!(circular reference)";
this.OnPropertyChanged(currentCell, "CellChanged");
return;
}
}
// If no Errors, Evaluate the Formula and Update the Value
currentCell.CellValue = expressionTree.Evaluate().ToString();
this.OnPropertyChanged(cell, "CellChanged");
}
// Update the Dependent Cells of Cell Being Changed
if (dependentCells.ContainsKey(currentCell))
{
foreach (SpreadsheetCell dependentCell in dependentCells[currentCell])
{
EvaluateSpreadsheetCell(dependentCell);
}
}
}
}
public void TestSetVariable()
{
SpreadsheetEngine.ExpressionTree expressionTree = new SpreadsheetEngine.ExpressionTree("5+4");
expressionTree.SetVariable("A1", 42);
var fieldInfo = expressionTree.GetType().GetField("root", BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance);
}
