new regexp library

[Henry Cejtin]

Dot  is  certainly  a fine program, but this thing that it produced is pretty
bad.  For one thing, it is horizontal  instead  of  vertical.   This  is  bad
beause  you  a  page  has more space vertically than horizontally.  Also, the
size is 9221 accross, which is just under 128 inches.  A bit wide compared to
any paper I have around here.

In  the  graph,  I  don't  understand  DFA transitions labelled with an empty
character class (e.g., n39 -> n38).  If this was actually the empty character
class,  then  you would never follow it, so that makes no sense.  If it is an
epsilon transition (i.e., you consum 0 characters travelling along this edge)
then these should only exist in the NFA, not the DFA.
...
Yes, look at state n4: It can go to state N3 on a tab character, but it looks
like it can also go to state n1 on a  tab  (assuming  that  the  `^'  in  the
n4 -> n1   character   class  really  means  the  complement  of  the  listed
characters.