Paul Eggert wrote:
> I doubt whether implementing regex optimizations along these
> lines would interest anybody other than automata theorists.
But for simpler optimizations, I think the regcomp() function
should implement optimizations that are dependent on the
internal algorithm used by regexec().
Just like a decent C compiler does constant propagation and
common subexpression elimination, a regex compiler should
transform
\(abc\|abra\) -> ab\(c\|ra\)
.*..*..* -> ...*
\(ace\|brace\) -> \(\|br\)ace (or vice versa?)
and similar things. Especially the last one, where it's
not clear to a user like me which of the two forms is the
more efficient one to execute.
Bruno
