public static object Evaluate(Syntax current, bool fromDivsion)
{
if (current.Kind == TokenKind.Expression)
{
ExpressionSyntax expression = current as ExpressionSyntax;
if (expression.AddOp != null)
{
AddOpSyntax add = expression.AddOp as AddOpSyntax;
if (add.Operator.Kind == TokenKind.Plus)
{
return((int)Evaluate(expression.Term, false) + (int)Evaluate(expression.Expression, false));
}
else
{
return((int)Evaluate(expression.Term, false) - (int)Evaluate(expression.Expression, false));
}
}
else if (expression.Term != null)
{
return(Evaluate(expression.Term, false));
}
}
else if (current.Kind == TokenKind.Term)
{
TermSyntax term = current as TermSyntax;
if (term.Multiply != null)
{
MultiOpSyntax multi = term.Multiply as MultiOpSyntax;
return((int)Evaluate(term.Factor, false) * (int)Evaluate(term.Term, false));
}
else if (term.Factor != null)
{
return(Evaluate(term.Factor, false));
}
}
else if (current.Kind == TokenKind.Factor)
{
FactorSyntax factor = current as FactorSyntax;
if (factor.Division != null)
{
MultiOpSyntax divide = factor.Division as MultiOpSyntax;
int a = (int)Evaluate(factor.Unit, false);
int b = (int)Evaluate(factor.Factor, true);
if (fromDivsion)
{
return(a * b);
}
return(a / b);
}
else if (factor.Unit != null)
{
return(Evaluate(factor.Unit, false));
}
}
else if (current.Kind == TokenKind.Unit)
{
UnitSyntax unit = current as UnitSyntax;
if (unit.Number != null)
{
return(Evaluate(unit.Number, false));
}
else if (unit.LeftParenthesis != null)
{
return(Evaluate(unit.Expression, false));
}
}
else if (current.Kind == TokenKind.Number)
{
return(current.Value);
}
return(0);
}
public static void PrintTree(Syntax root)
{
Stack <TreeState> tree = new Stack <TreeState>();
tree.Push(new TreeState(root, "", false));
PrintSection("Parse tree:");
while (tree.Count > 0)
{
var currentSyntax = tree.Pop();
var current = currentSyntax.Syntax;
var indent = currentSyntax.Indent;
var childIndent = currentSyntax.IsLast ? indent + " ":indent + "│ ";
var marker = currentSyntax.IsLast ? "└──":"├──";
Console.Write($"{indent}{marker}");
Console.ForegroundColor = ConsoleColor.DarkCyan;
Console.Write(current.Kind);
if (current.Value != null)
{
Console.Write($" {current.Value}");
}
Console.WriteLine();
Console.ResetColor();
switch (current.Kind)
{
// using stack cause we can write to console horizontally
// when pushing to the stack
// pushing inverse order of grammar
// cause last item should be printed at last
case TokenKind.Expression: {
ExpressionSyntax expression = current as ExpressionSyntax;
if (expression.AddOp != null)
{
tree.Push(new TreeState(expression.Expression, childIndent, true));
tree.Push(new TreeState(expression.AddOp, childIndent, false));
tree.Push(new TreeState(expression.Term, childIndent, false));
}
else if (expression.Term != null)
{
tree.Push(new TreeState(expression.Term, childIndent, true));
}
}; break;
case TokenKind.Term: {
TermSyntax term = current as TermSyntax;
if (term.Multiply != null)
{
tree.Push(new TreeState(term.Term, childIndent, true));
tree.Push(new TreeState(term.Multiply, childIndent, false));
tree.Push(new TreeState(term.Factor, childIndent, false));
}
else if (term.Factor != null)
{
tree.Push(new TreeState(term.Factor, childIndent, true));
}
}; break;
case TokenKind.Factor: {
FactorSyntax factor = current as FactorSyntax;
if (factor.Division != null)
{
tree.Push(new TreeState(factor.Factor, childIndent, true));
tree.Push(new TreeState(factor.Division, childIndent, false));
tree.Push(new TreeState(factor.Unit, childIndent, false));
}
else if (factor.Unit != null)
{
tree.Push(new TreeState(factor.Unit, childIndent, true));
}
}; break;
case TokenKind.Unit: {
UnitSyntax unit = current as UnitSyntax;
if (unit.Number != null)
{
tree.Push(new TreeState(unit.Number, childIndent, true));
}
else if (unit.LeftParenthesis != null)
{
tree.Push(new TreeState(unit.RightParenthesis, childIndent, true));
tree.Push(new TreeState(unit.Expression, childIndent, false));
tree.Push(new TreeState(unit.LeftParenthesis, childIndent, false));
}
}; break;
case TokenKind.Add_op: {
AddOpSyntax add = current as AddOpSyntax;
tree.Push(new TreeState(add.Operator, childIndent, true));
}; break;
case TokenKind.Mult_op: {
MultiOpSyntax multi = current as MultiOpSyntax;
tree.Push(new TreeState(multi.Operator, childIndent, true));
}; break;
case TokenKind.Division_op: {
DivisionOpSyntax div = current as DivisionOpSyntax;
tree.Push(new TreeState(div.Operator, childIndent, true));
}; break;
default: break;
}
}
}