Require that SSNs be neither preceded nor followed by digits

[waldoj]

Virtually any 10-plus-digit number is going to be matched, in part, by our regular expression. We really only want to match 9 digit numbers that are not preceded by or followed by digits. I've tried this:

(?:\D)(?!666|000|9\d{2})\d{3}(-?)(?!00)\d{2}\1(?!0{4})(?:\D)

but that also matches the preceding and following characters, returning results like A123-45-6789,. (The ?: ensures that the group isn't stored in memory by regex, but they're still being returned as part of the result.) Figure out how to require the presence of \D before and after, but not return them.

[waldoj]

I think we can address this in Ruby with \K. Instead of beginning and ending the regex with (?:\D), we'd use (\D\K), which means not to keep that portion. Unfortunately, BBEdit 10 (which I'm using to test this regex against the corpus of documents) doesn't support \K, so I can't say for sure that it'll work.

[waldoj]

D'oh—JRuby is based on Ruby 1.9.3. So \K, which requires Ruby 2, won't be supported. I'll need to come up with another method.