POSIX regex snarfed from Doug McIlroy's C++. Converted to C by Glenn

Fowler. *'d features have been added to Doug's original code. testre

should compile with other regex implementations, but you may need to

run with -c to catch non-terminating loops and memory faults.

FEATURE BRE ERE ARE

------- --- --- ---

negation NO expr \! expr !

conjunction NO expr \& expr expr & expr

NULL subgroups YES NO YES

word boundaries* \< expr \> \< expr \> < expr >

minimal match* NO REG_MINIMAL REG_MINIMAL

shell patterns* REG_SHELL NO NO

ksh patterns* NO NO REG_SHELL