public void Visit(NotExpr node)
{
VisitChildren (node.Children [0]);
string type = TypeStack.Pop ();
if (type != "Bool") {
throw new SemanticError ("Operator " + node.Name + " can not be applied to operand of type: " +
type, node.Children [0].Row, node.Children [0].Column);
}
}
public void Visit(NotExpr node)
{
VisitChildren (node.Children [0]);
StackValue boolean = ValueStack.Pop ();
// change true to false and false to true and push it to the stack
if (boolean.Value == "true") {
boolean.Value = "false";
} else {
boolean.Value = "true";
}
ValueStack.Push (boolean);
}
private Expression Expr()
{
Expression expr = new Expression ("expr", currentToken.Row, currentToken.Column);
if ((Token.Types)currentToken.Type == Token.Types.LeftParenthesis ||
(Token.Types)currentToken.Type == Token.Types.IntLiteral ||
(Token.Types)currentToken.Type == Token.Types.StringLiteral ||
(Token.Types)currentToken.Type == Token.Types.Identifier ||
(Token.Types)currentToken.Type == Token.Types.BoolLiteral) {
Expression left = Conjuct ();
Expression right = ExprLogical ();
if (right.Name != null) {
right.AddChild (left);
expr.AddChild (right);
return expr;
} else {
expr.AddChild (left);
return expr;
}
} else if ((Token.Types)currentToken.Type == Token.Types.Not) {
NotExpr notExpr = new NotExpr ("!", currentToken.Row, currentToken.Column);
Match (Token.Types.Not);
notExpr.AddChild (Expr ());
return notExpr;
}
throw new SyntaxError ("invalid token to start expression " + currentToken.Type,
currentToken.Row, currentToken.Column);
}