$a = "foo|{baz|qux}|fax";
@b = ($a =~ /(
        [^|\{]+
       |
        \{ [^}]+ \}
        )
        (?: \| | $ )
      /xg);


##</code><code>##

$VAR1 = [
          'foo',
          '{baz|qux}',
          'fax'
        ];


##</code><code>##

$VAR1 = [
          'foo',
          'baz',
          'qu}x}',
          'fax'
        ];