A regular expression (regexp) is a text string that describes
some set of strings. Functions that handle regular expressions,
based on GNU regexp-0.12, have been implemented (for more
details, see the GNU documentation about regexp rules). The
functions available from Search menu provide search forward or
backward and replace. Each of them prompts a dialog box to get
the target regexp. Regular expressions are composed of
characters and operators that match one or more characters. Here
is an abstract of commons operators: |matches one of a choice of
regular expressions. [...]matches one item of a list.
[^...]matches a single character not represented by one of the
list items. (...)treats any number of other operators (i.e.
subexpressions) as a unit. \digit matches a specified preceding
group. ^matches the beginning of line. $matches the end of line.
Smac provides the following functions: returns the position of
the next regular expression regexp, or -1 if regexp has not been
found, or -2 if regexp is not valid