A crazy idea for accurately tracking source position

[Alix Pexton via Digitalmars-d]

Just fixing an obvious typo in my code (that is still incomplete).
====

struct someRange
{
     ulong seq;
     bool fresh = true;
     long line;
     dchar front;
     // and lets just pretend that there is
     // somewhere for more characters to come from!

     void popFront()
     {
         // advance by whatever means to update front.
         if (front.isNewline)
         {
             ++line;
             fresh = true;
             return;
         }
         if (fresh)
         {
             if (front.isTab)
             {
                 seq = 0xffff_ffff_ffff_fffeL;
             }
             else
             {
                 seq = 0x1L;
             }
             fresh = false;
         }
         else
         {
             seq <<= 1;
             if (!front.isTab)
             {
                 seq |= 0x1L;
             }
         }
     }

     // and the rest...
}