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Code to strip outer parentheses

CADcasualty

Hi,

I am calling a routine that returns either a number or a string (the routine is figuring out a parent parameter defined in some upper parent in the hierarchy). The problem is that if a string is returned it is surrounded by a set of parentheses for every hierarchical level that was traversed finding the parent parameter. So the routine could return a straight number, or it could return some text surrounded by an arbitrary amount of parentheses e.g. "blah" or "(blah)" or "((((((blah))))))".

I can't edit the original routine and I'm stumped trying to figure out a way to remove all outer pairs of parentheses - can anybody point me to some code that does this. Please note that I only want to remove OUTER pairs of parentheses i.e. if I had "(((blah(0))))" then I'd want to end up with "blah(0)".

Many thanks in advance.

Parents
  • skillUser

    Hi,

    I think this is what you wanted :

    procedure(removeParens(item)
      cond(
        (stringp(item) removeParens(readstring(item)))
        (listp(item) mapcan('removeParens item))
        (t list(item))
      )
    )

    Results:

    str = "((((((blah))))))"
    removeParens(str)
    => (blah)

    str = "((((((blah(0)))))))"
    removeParens(str)
    => (blah 0)

    You could check to see if there is a cdr() of the returned result, if so return the whole result, otherwise return the car of the result:

    result = removeParens(str)
    if(cdr(result) result car(result))
    => blah  OR  (blah 0)


    Hopefully this helps?

    Regards,

    Lawrence.

  • CADcasualty
    in reply to skillUser

    Thanks Lawrence - this is almost what I want! I need matching pairs of OUTER parentheses removed. Specifically:

    if I had "(((blah(0))))" then I'd want to end up with "blah(0)"

Reply
  • CADcasualty
    in reply to skillUser

    Thanks Lawrence - this is almost what I want! I need matching pairs of OUTER parentheses removed. Specifically:

    if I had "(((blah(0))))" then I'd want to end up with "blah(0)"

Children
  • Andrew Beckett
    in reply to CADcasualty

    I'd use a pattern matching approach rather than relying on the SKILL parser. Otherwise if you have unusual characters in there, Lawrence's code would probably get a bit upset. Something like this would work:

    procedure(CCFremoveOuterParens(str)
  unless(CCFremoveOuterParens.pat
    CCFremoveOuterParens.pat=pcreCompile("^\\((.*)\\)$")
  )
  if(pcreExecute(CCFremoveOuterParens.pat str) then
    CCFremoveOuterParens(pcreSubstitute(CCFremoveOuterParens.pat "\\1"))
  else
    str
  )
)
  • skillUser
    in reply to CADcasualty

    But the blah(0) is reformatted to (blah 0) - they are the same in SKILL or LISP.

  • Andrew Beckett
    in reply to skillUser
    skillUser said:
    But the blah(0) is reformatted to (blah 0) - they are the same in SKILL or LISP

    Not sure the strings are necessarily SKILL though? What if you tried to do it on "((blah(+)))" (as a silly example)? That's why I went for the pattern matching approach - it's safer.

    Andrew.

  • skillUser
    in reply to Andrew Beckett

    True - I was just repurposing something that I had (and based on the assumption that the string would be parse-able by SKILL) rather than writing something new... Your solution is cleaner and safer and much less likely to choke.


    Cheers,

    Lawrence.

  • Andrew Beckett
    in reply to skillUser
    skillUser said:
    True - I was just repurposing something that I had (and based on the assumption that the string would be parse-able by SKILL) rather than writing something new

    Lawrence,

    I'm always a fan of taking advantage of the SKILL parser if you can - so it was a good idea! That's why I tend to format config files for utilities I write in a way that can be easily be slurped in by lineread() for example...

    Andrew.

  • CADcasualty
    in reply to skillUser

    Perfect! Thanks Andrew. BTW - the routine I was referring to was abIPar (which you wrote). Many thanks again!

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