Regular expression match that excludes characters inside parenthesis

Question

I have the following types of strings.

BILL SMITH (USA)
WINTHROP (FR)
LORD AT WAR (GB)
KIM SMITH

With these strings, I have the following constraints: 1. all caps 2. can be 2 to 18 charters long 3. should not have any white spaces or carriage returns at the end 4. the country abbreviation inside the parens should be excluded 5. some of the names will not have the country in parens and they should be matched too

After applying my regular expression I'd like to get the following:

BILL SMITH (USA)  => BILL SMITH
WINTHROP (FR) => WINTHROP
LORD AT WAR (GB) = LORD AT WAR
KIM SMITH => KIM SMITH

I came up with the following regular expression but I'm not getting any matches:

String.scan(\([A-Z \s*]{1,18})(^?!(\([A-Z]{1,3}\)))\)

I been banging my head on this for a while so if anyone can point error I'd appreciated it.

UPDATE:

I've gotten some great responses, however, so far none of the regular expression solutions have met all the constraints. The tricky part seems to be that some of the string has the country in parenthesis and some don't. In one case strings without the country was not being matched and in another it was returning the correct string along with the country abbreviation without the parenthesis. (See the comments on the second response.) One point of clarification: All of the strings that I will be matching will be the start point of the string. Not sure if that helps or not. Thanks again for all your help.

Answer 1

Here's one solution:

^((?:[A-Z]|\s){2,18}+?)(?:\s\([A-Z]+\))?$

See it on Rubular. Note that it counts 18 characters before the parenthesis - not sure how you want it to behave specificically. If you want to make sure the whole line isn't more than 18 characters, I suggest you just do unless line.length < 18 ... Similarly, if you want to make sure there is no whitespace at the end, I recommend you use line.strip. That'll greatly reduce the complexity of the Regexp you need and make your code more readable.

Edit: also works when no parentheses are used after the name.

Answer 2

The biggest error is that you wrote (^?!...) where you meant (?=...). The former means "an optional start-of-line anchor, followed by !, followed by ..., inside a capture group"; the latter means "a position in the string that is followed by ...". Fixing that, as well as makin a few other tweaks, and adding the requirement that the initial string end with a letter, we get:

[A-Z\s]{1,17}[A-Z])(?=\s*\([A-Z]{1,3}\)

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Update based on OP comments: Since this will always match at the start of a string, you can use \A to "anchor" your pattern to the start of the string. You can then get rid of the lookahead assertion. This:

\A[A-Z][A-Z\s]{0,16}[A-Z]

matches start-of-string, followed by an uppercase letter, followed by up to 16 characters that are either uppercase letters or whitespace characters, followed by an uppercase letter.