[luatex] Library for regular expressions in lualatex

[Саша Козловский]

Hello Everybody. I want in each formula replace all $$ on \[\] and $ on 
\(\) if before each $ it no char \,because it not exists any ways to 
override $ and $$ in lualatex. For example instead of formula $$a+b=c$$ 
must be formula \[a+b=c\] and,for example,instead of formula $a-b=0$ 
must be formula \(a-b=0\). All replacement i do in callback 
process_input_buffer. So i need in regexp,but lua in lualatex is not 
fully support regular expressions,so advice me please library,which use 
sintaksis of regular expressions like in python and which works in 
lualatex. Thanks everybody for the help.