Seems broken. It doesn't implement a proper regular expression engine. http://regexr.com/3f8ge http://regexr.com/3f8ge c.f. https://swtch.com/~rsc/regexp/rege

Seems broken. It doesn't implement a proper regular expression engine. http://regexr.com/3f8ge http://regexr.com/3f8ge c.f. https://swtch.com/~rsc/regexp/regexp1.html https://swtch.com/~rsc/regexp/regexp1.html