DB<35> x "don't" =~ / (.+?) (\b) /x
0  'don'
1  ''
  DB<36> x "don't" =~ / (.+?) (\b) /xg
0  'don'
1  ''            # boundaries always empty
2  '\''
3  ''
4  't'
5  ''


##</code><code>##

\w        [3]  Match a "word" character (alphanumeric plus "_", plus
                  other connector punctuation chars plus Unicode
                  marks)