This seems like a rather problematic approach, in both before and after variants:

  my ($pos, $first ) = ( pos $string, $1 ) if $string =~ m/([\[\{\]\},
+])/g;
  return unless defined $pos;

[download]
which I'd rather write as:
  $string =~ m/([\Q[]{},\E])/ or return;
  my($pos, $first) = ($+[0], $1);

[download]

With the code as is I'm not sure what you expect $pos and $first to be when the match fails, but if my reformulation is appropriate, it becomes clear that neither will ever be set to undef - that should either allow the remaining code to be simplified some, or point to a problem.

Hugo

In reply to Re^2: Refactoring challenge. by hv
in thread Refactoring challenge. by BrowserUk

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