([[=]+) a=[b]= y $1 =[
([[.]+) a.[b]. y $1 .[
[a[:xyz: - c - /[a[:xyz:/: unmatched [] in regexp
-[a[:xyz:] - c - /[a[:xyz:]/: unmatched [] in regexp
+[a[:xyz:] - c - Character class [:xyz:] unknown
[a[:]b[:c] abc y $& abc
-([a[:xyz:]b]+) pbaq y $1 ba
+([a[:xyz:]b]+) pbaq c - Character class [:xyz:] unknown
+[a[:]b[:c] abc y $& abc
+([[:alpha:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd
+([[:alnum:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01Xy
+([[:ascii:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01Xy__-- ${nulnul}
+([[:cntrl:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ${nulnul}
+([[:digit:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 01
+([[:graph:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01Xy__--
+([[:lower:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 cd
+([[:print:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01Xy__--
+([[:punct:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 __--
+([[:space:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1
+([[:word:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01Xy__
+([[:upper:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 AB
+([[:xdigit:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01
+([[:^alpha:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 01
+([[:^alnum:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 __-- ${nulnul}${ffff}
+([[:^ascii:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ${ffff}
+([[:^cntrl:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01Xy__--
+([[:^digit:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd
+([[:^lower:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 AB
+([[:^print:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ${nulnul}${ffff}
+([[:^punct:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01Xy
+([[:^space:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 ABcd01Xy__--
+([[:^word:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 -- ${nulnul}${ffff}
+([[:^upper:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 cd01
+([[:^xdigit:]]+) ABcd01Xy__-- ${nulnul}${ffff} y $1 Xy__-- ${nulnul}${ffff}
+[[:foo:]] - c - Character class [:foo:] unknown
+[[:^foo:]] - c - Character class [:^foo:] unknown
((?>a+)b) aaab y $1 aaab
(?>(a+))b aaab y $1 aaa
((?>[^()]+)|\([^()]*\))+ ((abc(ade)ufh()()x y $& abc(ade)ufh()()x
round\(((?>[^()]+))\) _I(round(xs * sz),1) y $1 xs * sz
'((?x:.) )' x y $1- x -
'((?-x:.) )'x x y $1- x-
+foo.bart foo.bart y - -