private Expr And()
{
var expr = Equality();
while (Match(TokenType.And))
{
var op = Previous();
var right = Equality();
expr = new Logical(expr, op, right);
}
return(expr);
}
private Expr Or()
{
var expr = And();
while (Match(TokenType.Or))
{
var op = Previous();
var right = And();
expr = new Logical(expr, op, right);
}
return(expr);
}
public object VisitLogical(Logical logical)
{
object left = logical.Left.Accept(this);
if (logical.Op.Type == OR && IsTrue(left))
{
return(left);//early out -> TRUE
}
if (logical.Op.Type == AND && !IsTrue(left))
{
return(left);//early out -> FALSE
}
object right = logical.Right.Accept(this);
return(right);
}
public object Visit(Logical expr)
{
var left = Evaluate(expr.Left);
if (expr.Op.Type == Or)
{
if (IsTruthy(left))
{
return(left);
}
}
else
{
if (!IsTruthy(left))
{
return(left);
}
}
return(Evaluate(expr.Right));
}
