(?:      non-capturing parentheses
      ^    start of string
       |   or
      \|   pipe character
   )
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   (?=     look-ahead, not part of match
       $   end of string
        |  or
       \|  pipe character
    )
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So I am looking for something between the start of string or a pipe and a pipe or the end of the string, ignoring whitespace, matching non-greedily. In order to make it work, I need to use each pipe twice, once for the string before the pipe, and then for the string following it. Thus the look-ahead assertion. HTH.