public override Pred CodeToPred(LNode expr, ref string errorMsg)
{
bool isInt = false;
PGIntSet set;
if (expr.IsIdNamed(_underscore))
{
set = PGIntSet.AllExceptEOF;
}
else if (expr.IsIdNamed(_EOF))
{
set = PGIntSet.EOF;
}
else if (expr.Calls(S.DotDot, 2))
{
int?from = ConstValue(expr.Args[0], ref isInt);
int?to = ConstValue(expr.Args[1], ref isInt);
if (from == null || to == null)
{
errorMsg = "Expected int32 or character literal on each side of «..»";
return(null);
}
set = PGIntSet.WithRanges(from.Value, to.Value);
}
else if (expr.Value is string)
{
return(Pred.Seq((string)expr.Value));
}
else
{
int?num = ConstValue(expr, ref isInt);
if (num == null)
{
errorMsg = "Unrecognized expression. Expected int32 or character literal instead of: " + expr.ToString(); // warning
return(null);
}
set = PGIntSet.With(num.Value);
}
set.IsCharSet = !isInt;
return(new TerminalPred(expr, set, true));
}
