/// <summary>
/// run step 123.
/// </summary>
/// <returns></returns>
public override Expr Parse()
{
var startToken = _tokenIt.NextToken;
// 1. index number: it's 1 based so substract 1.
var index = Convert.ToDouble(_tokenIt.NextToken.Token.Text) - 1;
var indexExpr = Exprs.Const(new LNumber(index), _tokenIt.NextToken);
_tokenIt.Advance();
// 2. "st" or "nd" or "rd" or "th"
_tokenIt.Advance();
// 3. identifier
var ident = _tokenIt.NextToken.Token.Text + "s";
var identExpr = Exprs.Ident(ident, _tokenIt.NextToken);
_tokenIt.Advance();
return(Exprs.Index(identExpr, indexExpr, false, startToken));
}
