X(\w+)(?=\s)|X(\w+) Xab y [$1-$2] [-ab]
#check that branch reset works ok.
+(?|(a)) a y $1-$+-$^N a-a-a
(?|a(.)b|d(.(o).)d|i(.)(.)j)(.) d!o!da y $1-$2-$3 !o!-o-a
(?|a(.)b|d(.(o).)d|i(.)(.)j)(.) aabc y $1-$2-$3 a--c
(?|a(.)b|d(.(o).)d|i(.)(.)j)(.) ixyjp y $1-$2-$3 x-y-p
.*?(?:(\w)|(\w))x abx y $1-$2 b-
0{50} 000000000000000000000000000000000000000000000000000 y - -
-^a?(?=b)b ab B $& ab # Bug #56690
-^a*(?=b)b ab B $& ab # Bug #56690
+^a?(?=b)b ab y $& ab # Bug #56690
+^a*(?=b)b ab y $& ab # Bug #56690
/>\d+$ \n/ix >10\n y $& >10
/>\d+$ \n/ix >1\n y $& >1
/\d+$ \n/ix >10\n y $& 10