internal protected virtual IEnumerable <Token> OutlineTokens(IEnumerable <Token> tokens)
{
yield return(Token.Special("BOF", 0));
Token last = null;
foreach (var token in tokens)
{
last = token;
yield return(token);
}
var eofPosition = last == null ? 0 : last.EndPosition;
yield return(Token.Special("EOF", eofPosition));
}
