问题
Making an argument parser. I want to split a string into an array where the delimiter is ", " except when preceded by "|". That means string
"foo, ba|, r, arg"
should result in
`["foo", "ba|, r", "arg"]`
I'm trying to use this regex: (?<!\|), which works in http://regexhero.net/tester/ but when I try
args.split(/(?<!\|), /)
in ruby, I get an error: undefined (?...) sequence: /(?<!\|), /
回答1:
Ruby's regex engine doesn't support lookbehind (yet).
You'd need to switch to 1.9 or use Oniguruma.
If that's not an option, you can search for |, and replace it with some sort of marker. After all is said and done, put the |, back.
You can also try a regex like:
/(?:[^|]), /
But obviously the (?:[^|]) is not zero-width, which means you'll need to do some extra work afterwards.
来源：https://stackoverflow.com/questions/7605615/regex-negative-lookbehind-in-ruby-doesnt-seem-to-work